Kepler Mission

Sunday December 13, 2009
Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.
Johannes Kepler, a German astronomer famous for his laws of planetary motion. Check out our Johannes Kepler facts page for more information.

Kepler was the mind that pulled together the observations of Galileo and the data from Tycho to figure out how the planets moved around the sun.


Although his three laws were not recognized in his day (scoffed was more like it!), these laws are still used in today’s science classes. The Kepler mission launched in March, 2009, and is designed to search for Earth-like planets orbiting other stars. Here’s a video that details the mission:


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Historic Space Missions

Sunday December 13, 2009

Voyager Mission

In 1977, NASA launched two small spacecraft called Voyager 1 and Voyager 2. Weighing only 800 kgs each, they collected a wealth of scientific data and thousands of photographs of the four giant planets in our Solar System. After visiting Jupiter and Saturn, Voyager 1’s trajectory left the ecliptic plane in order to photograph Saturn’s moon Titan. This meant that Voyager 1 would not visit any other planets. However, Voyager 2 continued on to visit Uranus and Neptune. Still today, Voyager 2 is the only spacecraft to have visited these two “ice giants” and their moons.


Both Voyagers are still in operation and providing unprecedented data that engineers and scientists using today to understand space. Both are expected to last until 2020-2025, at which time their atomic battery life will no longer support their electrical systems.



Pioneer 10

Launched on March 2, 1972, Pioneer 10 was the first spacecraft to travel through the asteroid belt, and the first spacecraft to make direct observations and obtain close-up images of Jupiter. Pioneer 10 is now coasting silently through deep space (its last transmission was in 2003) toward the red star Aldebarran (the eye of Taurus the Bull), a journey of over 2 million years.  Originally intended as a 21-month program, this 30-year mission has more than paid for itself with discoveries and science.



Mariner 10 was a robotic space probe launched on 3 November 1973 to fly by the planets Mercury and Venus. It was launched approximately 2 years after Mariner 9 and was the last spacecraft in the Mariner program (Mariner 11 and 12 were re-designated Voyager 1 and Voyager 2). The mission objectives were to measure Mercury’s environment, atmosphere, surface, and body characteristics and to make similar investigations of Venus. Secondary objectives were to perform experiments in the interplanetary medium and to obtain experience with a dual-planet gravity-assist mission.


During its flyby of Venus, Mariner 10 discovered evidence of rotating clouds and a very weak magnetic field.


Mariner 10 flew past Mercury three times in total. Owing to the geometry of its orbit — its orbital period was almost exactly twice Mercury’s — the same side of Mercury was sunlit each time, so it was only able to map 40-45% of Mercury’s surface, taking over 2800 photos. It revealed a more or less moon-like surface. It thus contributed enormously to our understanding of the planet, whose surface had not been successfully resolved through telescopic observation.



Apollo 11/Saturn V Rocket Launch

Sunday December 13, 2009

This is the actual video of the very first moon landing of the Apollo 11 mission in 1969! Neil Armstrong was the first man to set foot on the moon with his now legendary words “One small step for man, a giant leap for mankind.” This is a truly amazing video. If you think about it, you have orders of magnitude more processing power in your mobile phone than they did in the whole space craft!! Incredible!






Retrograde Motion

Sunday December 13, 2009

mars-retrogradeIf you watch the moon, you’d notice that it rises in the east and sets in the west. This direction is called ‘prograde motion’. The stars, sun, and moon all follow the same prograde motion, meaning that they all move across the sky in the same direction.


However, at certain times of the orbit, certain planets move in ‘retrograde motion’, the opposite way. Mars, Venus, and Mercury all have retrograde motion that have been recorded for as long as we’ve had something to write with. While most of the time, they spend their time in the ‘prograde’ direction, you’ll find that sometimes they stop, go backwards, stop, then go forward again, all over the course of several days to weeks.


Here are videos I created that show you what this would look like if you tracked their position in the sky each night for an year or two.


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Mercury and Venus Retrograde Motion

This is a video that shows the retrograde motion of Venus and Mercury over the course of several years. Venus is the dot that stays centered throughout the video (Mercury is the one that swings around rapidly), and the bright dot is the sun. Note how sometimes the trace lines zigzag, and other times they loop. Mercury and Venus never get far from the sun from Earth’s point of view, which is why you’ll only see Mercury in the early dawn or early evening.




Retrograde Motion of Mars

You’ve probably heard of epicycles people used to use to help explain the retrograde motion of Mars. Have you ever wondered what the fuss was all about? Here’s a video that traces out the path Mars takes over the course of several years. Do you see our Moon zipping by? The planets, Sun, and Moon all travel along line called the ‘ecliptic’, as they all are in about the same plane.



 
Download Student Worksheet & Exercises


Exercises


  1. During which of the months does Mars appear to move in retrograde?
  2.  Why does Mars appear to move backward?
  3. Which planets have retrograde motion?

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Satellite Crash!

Sunday December 13, 2009

The Hubble Space Telescope (HST) zooms around the Earth once every 90 minutes (about 5 miles per second), and in August 2008, Hubble completed 100,000 orbits! Although the HST was not the first space telescope, is the one of the largest and most publicized scientific instrument around. Hubble is a collaboration project between NASA and the ESA (European Space Agency), and is one of NASA’s “Great Observatories” (others include Compton Gamma Ray Observatory, Chandra X-Ray Observatory, and Spitzer Space Telescope). Anyone can apply for time on the telescope (you do not need to be affiliated with any academic institution or company), but it’s a tight squeeze to get on the schedule.


Hubble’s orbit zooms high in the upper atmosphere to steer clear of the obscuring haze of molecules in the sea of air. Hubble’s orbit slowly decays over time and begins to spiral back into Earth until the astronauts bump it back up into a higher orbit.


But how does a satellite stay in orbit? Try this experiment now:


Materials:


  • marble
  • paper
  • tape

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Download Student Worksheet & Exercises


Troubleshooting: Expect to find marbles flying everywhere with this experiment! This quick activity demonstrates the idea of centripetal (centrifugal) acceleration. What happens when you circle the cone too slow or too fast? The marble itself is the satellite (like HST), and the cone’s apex (tip) is the Earth. When the marble zooms around too slow, it falls back into the Earth. So what keeps it up in “orbit”?


The faster an object moves, the greater the acceleration against the force of gravity (toward the Earth in this case). Think back to the Physics lab – when a marble went too slow through the roller coaster loop, it crashed back to the floor. When it went too fast, it flew off the track. There was a certain speed that was needed for the marble to stay in the loop and on course. The same is true for satellites in outer space.


If you have trouble with this experiment, just replace the paper cone with a disposable cup with a lid and try again (with the lid in place), and see if you can keep the marble circling around the top rim.


Exercises


  1.  What happens when your marble satellite moves too slowly?
  2.  What happens when the marble satellite orbits too fast?
  3. What effect does changing the marble mass have on your satellite speed?
  4.  How is this model like the real thing?

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Alpha Particle Detector

Sunday December 13, 2009

This experiment is for advanced students. Here is another way to detect cosmic rays, only this time you’ll actually see the thin, threadlike vapor trails appear and disappear. These cobwebby trails are left by the particles within minutes of creating the detector. (Be sure to complete the Cosmic Ray Detector first!)


In space, there are powerful explosions (supernovas) and rapidly-spinning neutron stars (pulsars), both of which spew out high energy particles that zoom near the speed of light. Tons of these particles zip through our atmosphere each day. There are three types of particles: alpha, beta, and gamma.


Did you know that your household smoke alarm emits alpha particles? There’s a small bit (around 1/5000th of a gram) of Americium-241, which emits an alpha particle onto a detector. As long as the detector sees the alpha particle, the smoke alarm stays quiet. However, since alpha particles are easy to block, when smoke gets in the way and blocks the alpha particles from reaching the detector, you hear the smoke alarm scream.


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Alpha particles are actually high speed helium nuclei (which is two protons and two neutrons stuck together). They were named long before we knew what they were of, and the name stuck. Alpha particles are pretty heavy and slow, and most get stopped by just about anything, a sheet of paper or your skin. Because of this, alpha particles are not something people get excited about, unless you actually eat the smoke detector.


Both brick buildings as well as people emit beta particles. Beta particles are actually high speed electrons or positrons (a positron is the antimatter counterpart to the electron), and they are quick, fast, and light. You can stop a beta particle by holding up a thin sheet of plastic or tinfoil.


When you hold the jar in your hands, you warm it slightly and cause the air inside to get saturated with alcohol vapor. When the alpha particles (cosmic rays) zip through this portion of the jar, they quickly condense the alcohol and create spider-webby vapor trails. Try using a magnet to deflect the cosmic rays.


Here’s what you need:


  • rubbing alcohol
  • clean glass jar
  • black felt
  • hot glue gun
  • magnet
  • flashlight
  • scissors
  • dry ice and heavy gloves for handling the dry ice (and adult help)


 
Download Student Worksheet & Exercises


You will be making a special cloud chamber that holds alcohol gas inside. When you hold the jar in your hands, you warm it slightly and cause the air inside to get saturated with alcohol vapor. When the alpha particles (cosmic rays) zip through this portion of the jar, they quickly condense the alcohol and create spider-webby vapor trails. Kind of like when a jet flies through the air – you can’t always see the jet, but the cloud vapor trails streaming out behind stay visible for a long time. In our case, the vapor trails are visible for only a couple of seconds.


  1. Cut your felt to the size of the bottom of your jar.  Glue the felt to the bottom of the jar.
  2. Cut out another felt circle the size of the lid and glue it to the inside surface of the lid.
  3. Cut a third felt piece, about 2 inches wide, and line the inside circumference of the jar, connecting it with the bottom felt. Glue it into place.
  4. Strap goggles on your face. No exceptions.
  5. Very carefully pour a tablespoon or two of the highest concentration of rubbing alcohol onto the felt in the jar. You don’t need much. Swirl it around to distribute it evenly. Do the same for the lid. All the felt pieces should be thoroughly saturated. Cap the jar and leave it for ten minutes while you explain about dry ice (see safety precautions above under Important Project Considerations.
  6. Your teacher is coming around with the dry ice. Remove the lid and your teacher will place a small piece of dry ice right on the lid. Invert the jar right over the lid. Leave the jar upside down.
  7. DO NOT SCREW ON THE CAP TIGHTLY! Leave it loose to allow the pressure to escape.
  8. Sit and wait and watch carefully for the tiny, thin, threadlike vapor trails.
  9. What do you think the magnet is for? (Hint: Keep it outside the jar.)

What’s Going On?

Cosmic rays have a positive charge, as the particles are usually protons, though one in every 100 is an electron (which has a negative charge) or a muon (also a negative charge, but 200 times heavier than an electron).  On a good day, your cosmic ray indicator will blip every 4-5 seconds.  These galactic cosmic rays are one of the most important problems for interplanetary travel by crewed spacecraft.


Most cosmic rays zoom to us from extrasolar sources (stars that are outside our solar system but inside our galaxy) such as high-energy pulsars, grazing black holes, and exploding stars (supernovae).  We’re still figuring out whether some cosmic rays started from outside our own galaxy. If they are from outside our galaxy, it means that we’re getting stuff from quasars and radio galaxies, too!


Cosmic rays are fast-moving, high-energy, charged particles. The particles can be electrons, protons, the nucleus of a helium atom, or something else. In our case, the cosmic rays we’re detecting are “alpha particles.” Alpha particles are actually high-speed helium nuclei (helium nuclei are two protons and two neutrons stuck together). They were named “alpha particles” long before we knew what they were made of, and the name just kind of stuck.


Did you know that your household smoke alarm emits alpha particles? Most smoke detectors contain a small bit (around 1/5,000th of a gram) of Americium-241, which emits an alpha particle onto a detector. As long as the detector sees the alpha particle, the smoke alarm stays quiet. However, since alpha particles are easy to block, when smoke gets in the way and blocks the alpha particles from reaching the detector, you hear the smoke alarm scream.


Alpha particles are pretty heavy and slow, and most get stopped by just about anything, like a sheet of paper or your skin. Because of this, alpha particles are not something people get very excited about, unless you actually eat the smoke detector and ingest the material (which is not recommended).


Both brick buildings as well as people emit beta particles. Beta particles are actually high-speed electrons or positrons (a positron is the antimatter counterpart to the electron), and they are quick, fast, and light. When an electron hit the foil ball, it traveled down and charged the foil leaves, which deflected a tiny bit inside the electroscope. A beta particle has a little more energy than an alpha particle, but you can still stop it in its tracks by holding up a thin sheet of plastic (like a cutting board) or tinfoil.


Important Project Considerations:


After creating your detector: You can bring your alpha particle detector near a smoke alarm, an old glow-in-the-dark watch dial or a Coleman lantern mantel. You can go on a hunt around your house to find where the particles are most concentrated. If you have trouble seeing the trails, try using a flashlight and shine it on the jar at an angle.


You will also be working with dry ice. The dry ice works with the alcohol to get the vapor inside the jar at just the right temperature so it will condense when hit with the particles. Note that you should NEVER TOUCH DRY ICE WITH YOUR BARE HANDS. Always use gloves and tongs and handle very carefully. Keep out of reach of children – the real danger is when kids think the ice is plain old water ice and pop it in their mouth.


If your dry ice comes in large blocks, the easiest way to break a large chunk of dry ice into smaller pieces is to insert your hands into heavy leather gloves, wrap the dry ice block in a few layers of towels, and hit with a hammer. Make sure you wrap the towels well enough so that when the dry ice shatters, it doesn’t spew pieces all over. Use a metal pie plate to hold the chunks while you’re working with them. Store unused dry ice in a paper bag in a cooler or the coldest part of the freezer. Dry ice freezes at -109 degrees Fahrenheit. Most freezers don’t get that cold, so expect your dry ice to disappear soon.


TIP: You can bring your alpha particle detector near a smoke alarm, an old glow-in-the-dark watch dial or a Coleman lantern mantel. You can go on a hunt around your house to find where the particles are most concentrated. If you have trouble seeing the trails, try using a flashlight and shine it right on the jar.


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Unit 7: Astrophysics Video

Sunday December 13, 2009

6-newtonianThere are TWO videos for this Astronomy Lesson, both of which cover different parts of astronomy. The first video is all about telescopes, and I’ll walk you step by step through what it’s really like to get a telescope, set it up and work with one of these super cool instruments. After you’re done with this video, click over to the experiments section where you’ll have a front-row seat to a planetarium-style star show.


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Want to buy a telescope?

What if you and I went shopping together for everything you needed to get started with telescope viewing? Would you like to see what I would recommend getting started with? Note that these are my personal recommendations I would select for my own kids. These items listed below are entirely OPTIONAL and not required for this unit on Astronomy. I do not receive anything for giving you these links – think of these items below as a referral from one hobbyist to another. Bookmark this page so you have these recommendations for when you need it.


  • SkyQuest XT8i Computerized IntelliScope This is the best deal for the dollar on the market, and the mount is low and stable enough for astronomers of all ages to use easily. If you’re in the market for an expensive, compact scope, then the Celestron 8″ SCT is the one to seriously consider. Note that both these scopes have exactly the same size mirrors, only the SCT never needs alignment.
  • Padded Telescope Case Don’t even think about skimping on the case!  Get a good one to protect your investment for years to come.
  • EZ Finder II Telescope Reflex Sight This will save you hours of frustrations over using the included finder-scope. Simply swap it out with the finder-scope and you’re good to go.
  • Variable Polarizing Telescope Filter This is like putting sunglasses on your scope so you can look at the moon without blinding your eyes. (This is NOT for the sun – that requires a solar filter.) It’s variable so you can change the amount of incoming light as the moon waxes and wanes.
  • LaserMate Deluxe Telescope Collimator This nifty device will keep your telescope in proper alignment so your views are at their best.
  • Stratus Wide-Field Telescope Eyepieces Get the 17mm eyepiece (or closest size) first, and you’ll be blown away by how much more you can see over the small eyepieces that come with the scope.  You can optionally get a carrying case to hold all your optical gear in a safe place.
  • Green Laser Pointer Get this one for Dad or Grandpa to play with as you point out the constellations to your kids.  Don’t put it on your scope in the special bracket they sell with it, as the laser will burn out quickly if you leave it on for too long (that’s what they don’t tell you in the ad for the bracket). The laser isn’t something to get your kids – it’s too bright and dangerous to use indoors and should only be used by adults outside… and only for astronomy.

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Unit 7: Astrophysics (Particle Physics) Video

Sunday December 13, 2009

This video gets you started on the right foot. We’ll outline what’s coming up for this unit and how to get the most out of our lesson together. Enjoy!



Buying a Telescope: How to Avoid Being Ripped Off

Thursday December 10, 2009

6-newtonianIf your kid is crazy for Astronomy, get your hands on a $25 copy of Guy Ottewell’s Astronomical Calendar. You won’t find a better, more complete yearly almanac of astronomy anywhere. (In fact, most sources use Ottewell’s information in their publications.)


If a telescope is in your near future, here are a few of my personal recommendations. (Please note that I do not sell any of these telescopes, nor do I get paid for posting these links.  Think of this as a sneak peek into my personal collection.)


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Best beginner’s telescope for kids is the 8? Dob by Orion. This is the telescope they’ll have through college. The eyepiece isn’t sky-high, nor is the price.  The mount is near the bottom of the scope, making it easy for kids to operate. The best way to learn the night sky is to get a scope and start looking around.  If you’re nervous about finding things to point to, then you might want to look at this telescope, which finds objects for you – the 8? GO-TO Dob. If your kid has already mastered telescope operation and you’re looking for an upgrade, then have a look at one of my personal favorites –  8″ Reflector. This is the scope I use the most when working with families and public events. Click here for an instructional video on how to use a telescope (including a peek at my 8″ Reflector mentioned above).


Your new telescope is going to come with two hard-to-use and practically useless eyepieces.  Toss them out and order a set of the best eyepieces on the market for your dollar, the Widefield Stratus. Make sure you get at least one when you purchase your telescope. If you’re only getting one, make it a 17mm –  this one’s best for close-up planetary and lunar viewing as well as deep sky viewing.


If you’re wanting to do a lot of lunar viewing, pick up a variable 1.25? polarizing filter . They’re like sunglasses for your telescope, as the moon is very bright compared with everything else! The rest of the filters, like the colored filters, UV and pollution blockers, and O-III filters you can wait on. As a beginner, you’re not going to know how and when to use thes, nor are you going to see much of a difference when you do.


Don’t forget to get padded cases to keep your telescope protected. Although it’s tempting to keep your telescope uncovered and on display, don’t. You need to keep your optics clean and scratch-free.


If you don’t mind shopping around for a bargain, you can find great deals for telescopes at AstroMart.


Shoestring Budget Telescopes Kids can make their own small refractor telescope or use a tabletop Dobsonian telescope, but these are both only good for viewing the moon and things like birds and trees.


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Space Station Tour

Tuesday December 8, 2009

This is a FOUR-PART video series that takes you on a complete tour of the International Space Station, guided by a NASA astronaut and filmed in the summer of 2009. Enjoy!


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Easy Dice Game for Honing Math Skills

Thursday December 3, 2009

Did you know I carry a set of dice in my pocket just for this game? It's as old as the hills and just as fun to play now as it was when I was a little math whiz back in 2nd grade.  (No kidding - when we had 'math races', I was always team captain.  Not quite the same thing as captain on the soccer field, though...)

This is one of those quick-yet-satisfying dice games you can play to hone your thinking skills and keep your kids busy until the waiter arrives with your food.  All you need are five or six standard 6-sided dice and two 12-sided dice.  (Note - if you can't find the 12-sided dice, just skip it for now.  You can easily substitute your brain for the 12-sided dice.  I'll show you how.)
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You need to do two things to play this game. You can use a calculator with this game, but usually the kids without the calculator win the round, as it usually takes longer to punch in the numbers than figure out the different possibilities in your head (and that's what you're working on, anyway!) If  your kid is a highly visual learner, then hand them a scratch pad and a pencil so they can scribble down stuff as they go.

Download Student Worksheet & Exercises

First, roll the two 12-sided dice. Multiply the two numbers in your head.  If you rolled a 6 and 6, you'd now have 36. That's your target number.  If you don't have the 12-sided dice, just think up two numbers, each between 1 and 12 and use those.

Next, roll the 6-sided dice. Now, using your arithmetic skills, figure out a way to add, subtract, multiply or divide those three numbers to get the number you rolled with the first set.  So if you rolled six 6-sided dice and got 4, 5, 2, 1, 1, 5, you could do this:

(Red numbers are the ones rolled on 6-sided dice.)

(4 x 5) - 2 = 18

18 x (1 + 1) = 36

You don't have to use all the numbers, but you can't double up and use a 4 twice if you only rolled one 4.  And that's it!  It's loads of fun and engaging, because it's got more than one answer.  And sometimes there's no answer (although rarely!). As you get faster and better at this game, try taking away one or two of the dice.  It's more challenging.

HOT TIP: You can add in the use of exponents when your kids get the hang of the game. An exponent tells you how many times to multiply a number by itself. For example, a 2 with a 3 exponent looks like: 23 = 2 x 2 x 2 = 8. To use exponents, simply use one of the numbers as an exponent. For example, if you rolled five 6-sided dice and got 5, 2, 3, 2, 4, you can do this to get 36 (given 36 came from the 12-sided dice):

(Red numbers are the ones rolled on 6-sided dice.)

(5 x 2) = 102 = 100

100 - (43) = 36

When your kids get good, you can up the ante and use a set similar to what I have in my purse: one 20-sided double dice and a handful of 6-sided. Math craze, anyone?

Exercises

No dice? Try these combinations that I rolled and recorded for you. I rolled six 6-sided dice and two 12-sided dice. Can you figure out a combination that would make each target number? Remember that the target number is the product (multiplication) of the two numbers from the 12-sided dice.

6-sided dice               12-sided dice

  1. 2,3,5,6,1,3         ---     10,2
  2. 4,3,6,4,5,3         ---     12,9
  3. 1,6,4,4,2,1         ---     5,8
  4. 4,1,1,1,2,3         ---     3,9
  5. 1,6,6,5,5,1         ---     9,7
  6. 2,1,4,5,2,2         ---     6,3
  7. 3,1,6,5,4,1         ---     11,4
  8. 4,3,6,4,5,3         ---     12,7
  9. 2,2,3,3,4,6         ---     4,6
  10. 3,5,6,1,3,3         ---     6,9

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Astronomy Lecture Series

Tuesday December 1, 2009

8x10.aiThis lecture series is from an astronomy course at Ohio State. It’s a 20-week college-level course, so don’t feel like you’ve got to do it all in one night!  You’ll learn about the solar system, planets, and universe through a well-organized set of lectures that really brings astronomy, human history, and current technology together. This content is appropriate for advanced students and above.


Why bother offering high school students these college-level classes? Because if you’re like me, you’re always thirsty for more, and you’re not picky about where it comes from.  If you learn just one new thing from these astronomy talks, then you are one step further along your science journey and it was worth your time.


You can either download the podcasts to your MP3 player or directly access the MP3 files.  There are slides along with the lectures, but don’t feel like you have to use them – the lectures are meaty enough on their own.  Ready?


Click here to access Prof. Roger Pogge’s Astro 161 Lectures (Part 1)


Click here to access Prof. Roger Pogge’s Astro 162 Lectures (Part 2)


Resonance Exerices

Sunday November 29, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


Some of these questions you might recognize from the last lesson on potential energy, but we put them here again so you can see how they are inter-related. Have fun!


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Section One:

1. Which of our body parts function as antennae?


2. Why do I call those antennae?


3. Why do we have two ears?


Section Two:

1. Sound travels by waves. Transverse or longitudinal waves?


2. Sound travels faster in air, water, or solids?


3. Why does sound travel faster in that medium?


4. Would sound travel faster on a hot day or a cold day? Why?


5. Which travels faster, light or sound?


6. If you see a firework and hear the sound one second later, how far away is the firework?


7. If you see lightning and hear the lightning 10 Mississippi’s, uh I mean seconds, later, how far is the lightning?


Section Three:

1. If sound is a form of energy, what’s moving?


2. All sound comes from what?


3. What kind of a wave is sound?


4. What does frequency have to do with sound?


5. What does amplitude have to do with sound?


Section Four:

1. What causes sound?


2. What vibrates?


3. What is natural frequency?


4. Why do objects make different noises if they are hit or dropped or plunked?


5. What three things determine something’s natural frequency?


6. What is resonance?


7. If something is vibrating at 30,000 Hz, can we hear it?


8. What happens if energy is continued to be put into something resonating?


Need answers?

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Answers to Resonance Exercises

Sunday November 29, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.


Answers:
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1. Our antennae are our ears, eyes, and skin.


2. Antennae pick up energy. Our eyes, ears and skin all pick up energy. Our brain then interprets the energy as light, sound or heat. By the way, you may be asking, “What about the nose? Is our nose an antenna”? Not in my opinion. Molecules have to come into the nose and land on smell sensors to register as a smell. Noses detect matter (molecules), not energy.


3. Our two ears, plus our brain allow us to be fairly accurate at knowing where sounds are coming from. The sound will hit one ear before hitting the other and our brain can do the math and figure out which direction.


Section Two:

1. Longitudinal. The waves travel with the medium.


2. Solids


3. The particles are close together. The closer the particles the faster sound travels.


4. A cold day, since the molecules are closer together.


5. Light is much faster.


6. Sound travels 1000 ft/sec, so that firework is 1000 feet away.


7. Take 10 seconds and divide it by 5. So the lightning is 2 miles away.


Section Three:

1. Energy is the ability to move something against a force. In the case of sound, molecules are moving.


2. Vibrations. No vibration, no sound.


3. Longitudinal wave.


4. Frequency determines the pitch of the sound. The higher the frequency, the higher the pitch. The lower the frequency the lower the pitch.


5. The higher the amplitude of the wave, the louder the sound is. Higher amplitude means more energy which means louder sound.


Section Four:

1. Something vibrating causes sound. The sound waves are carried from the vibrating thing to your ears by longitudinal waves.


2. Everything! Couches, clams, mobile homes, they all vibrate.


3. The frequency something tends to vibrate at.


4. They make different noises because they vibrate at their natural frequency. When they are plunked the frequency that they vibrate at causes the sound wave that we hear.


5. Size, weight, and the material of an object determine its natural frequency.


6. Resonance is when something is vibrating at the same natural frequency as something else and causes that something else to vibrate as well.


7. No. Our ears have a natural frequency between 20-20,000 Hz. They will not vibrate at frequencies outside that range so we cannot hear something that vibrates at 30,000 Hz. Our ears can only be resonated by vibrations between 20-20,000 Hz.


8. If something continues to be resonated by something else, the thing that’s being resonated will vibrate more and more. Eventually, unless the energy is stopped or the vibration is slowed, the object being resonated may break. This is how singers can break wine glasses. They can hit a note that resonates the wine glass. As they keep singing, the wine glass vibrates more and more until it shatters!


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Vibrations Exercises

Sunday November 29, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


Some of these questions you might recognize from the last lesson on potential energy, but we put them here again so you can see how they are inter-related. Have fun!


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Section One:

1. What starts waves?


2. Where is work being done in a wave?


3. With the rope wave, what moved from partner to partner?


4. What is frequency?


5. What is Hertz?


6. If a swing is vibrating at .5 Hz, how many times does it go back and forth in 1 second?


7. If a yo-yo goes up and down 10 times in 10 seconds what is its Hertz?


8. If you create a rope wave by moving your hand up and down twice in one second, what’s the Hertz of that wave?


Section Two:

1. How does energy move?


2. True or false: the particles in a wave move from where the wave starts to where the wave ends up.


3. What is having work done on it in a wave?


4. What are the two type of waves?


5. In which wave does the particles vibrate in the same direction as the wave?


6. In which wave does the particles vibrate perpendicularly to the direction of the wave?


7. What does wavelength mean?


8. What does amplitude mean?


9. Which of the following has the longer wavelength?



10. Which of the following has the larger amplitude?



Need answers?

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Answers to Vibrations Exercises

Sunday November 29, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for printable questions and answers.


Answers:
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Section One:

1. Vibrating particles of some sort.


2. Work is done by the particles moving a distance against a force.


3. Energy. The particles didn’t move from partner to partner, the rope didn’t move across the room, the energy from one person moved in the form of a wave across the room.


4. Frequency is how many times something vibrates in a second. Something that is vibrating quickly is said to have a high frequency, something that is vibrating slowly is said to have a low frequency.


5. A Hertz is a measure of frequency. One Hertz is one vibration per second.


6. One half a time. The swing would swing forward or backward in one second. It would not go back and forth.


7. The yo-yo’s Hertz would be one. One vibration (up and down) per second would be 10 vibrations in 10 seconds.


8. 2 Hz. 2 vibrations per second.


Section Two:

1. Energy moves by waves.


2. False; particles only vibrate, they do not move along the wave.


3. Particles are being moved against a force. Work is being done on them and they are doing work on other particles.


4. Transverse and longitudinal.


5. Longitudinal.


6. Transverse.


7. Wavelength is the distance between two like parts of the wave.


8. Amplitude is the height of the wave.


9. “A” has the longer wavelength.


10. “B” has a larger amplitude.


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Air Horns & Sonic BOOM!

Sunday November 29, 2009

f18Sound can change according to the speed at which it travels. Another word for sound speed is pitch. When the sound speed slows, the pitch lowers. With clarinet reeds, it’s high. Guitar strings can do both, as they are adjustable. If you look carefully, you can actually see the low pitch strings vibrate back and forth, but the high pitch strings move so quickly it’s hard to see. But you can detect the effects of both with your ears.


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The range of your ears is about 20 – 20,000 Hz (cycles per second). Bats and dogs can hear a lot higher than we can. The image (right) is a real picture of an aircraft as it breaks the sound barrier – meaning that the aircraft is passing the speed that sounds travels at (about 700 mph). The white cloud you see in the photo is related to the shock waves that are forming around the craft as it moves into supersonic speeds. You can think of a shock wave as big pressure front, which creates clouds. In this photo, the pressure from the shock waves is condensing the water vapor in the air.


There are lots of things on earth that break the sound barrier – bullets and bullwhips, for example. The loud crack from a whip is the tip zipping faster than the speed of sound.


shockwaveSo why do we hear a boom at all? Sonic booms are created by air pressure (think of how the water collects at the bow of a boat as it travels through the water). The vehicle pushes air molecules aside in such a way they are compressed to the point where shock waves are formed. These shock waves form two cones, at the nose and tail of the plane. The shock waves move outward and rearward in all directions and usually extend to the ground.


As the shock cones spread across the landscape along the flightpath, they create a continuous sonic boom. The sharp release of pressure, after the buildup by the shock wave, is heard as the sonic boom.



How to Make an Air Horn

Let’s learn how to make loud sonic waves… by making an air horn. Your air horn is a loud example of how sound waves travel through the air. To make an air horn, poke a hole large enough to insert a straw into the bottom end of a black Kodak film canister. (We used the pointy tip of a wooden skewer, but a drill can work also.) Before you insert the straw, poke a second hole in the side of the canister, about halfway up the side.


Here’s what you need:


  • 7-9″ balloon
  • straw
  • film canister
  • drill and drill bits

Grab an un-inflated balloon and place it on your table. See how there are two layers of rubber (the top surface and the bottom surface)? Cut the neck off a balloon and slice it along one of the folded edges (still un-inflated!) so that it now lays in a flat, rubber sheet on your table.


Drape the balloon sheet over the open end of the film canister and snap the lid on top, making sure there’s a good seal (meaning that the balloon is stretched over the entire opening – no gaps). Insert the straw through the bottom end, and blow through the middle hole (in the side of the canister).


You’ll need to play with this a bit to get it right, but it’s worth it! The straw needs to *just* touch the balloon surface inside the canister and at the right angle, so take a deep breath and gently wiggle the straw around until you get a BIG sound. If you’re good enough, you should be able to get two or three harmonics!



 


Download Student Worksheet & Exercises


Troubleshooting: Instead of a rubber band vibrating to make sound, a rubber sheet (in the form of a cut-up balloon) vibrates, and the vibration (sound) shoots out the straw. This is one of the pickiest experiments – meaning that it will take practice for your child to make a sound using this device. The straw needs to barely touch the inside surface of the balloon at just the right angle in order for the balloon to vibrate. Make sure you’re blowing through the hole in the side, not through the straw (although you will be able to make sounds out of both attempts).


Here’s a quick video where you can hear the small sonic boom from a bull whip:



Since most of us don’t have bull whips, might I recommend a twisted wet towel? Just be sure to practice on a fence post, NOT a person!


Exercises 


  1. Why do we use a straw with this experiment?
  2. Does the length of the straw matter? What will affect the pitch of this instrument?

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The Best Parent-Annoyer Ever

Sunday November 29, 2009

This is one of my absolute favorites, because it’s so unexpected and unusual… the setup looks quite harmless, but it makes a sound worse than scratching your nails on a chalkboard. If you can’t find the weird ingredient, just use water and you’ll get nearly the same result (it just takes more practice to get it right). Ready?


NOTE: DO NOT place these anywhere near your ear… keep them straight out in front of you.


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Here’s what you need:


  • water or violin rosin
  • string
  • disposable plastic cup
  • pokey-thing to make a hole in the cup


 
Download Student Worksheet & Exercises


Exercises


  1. What does the rosin (or water) do in this experiment?
  2. What is vibrating in this experiment?
  3. What is the cup for?

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Seeing Sound Waves

Sunday November 29, 2009

This section is actually a collection of the experiments that build on each other.  We’ll be playing with sound waves, and the older students will continue on after this experiment to build speakers.


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Here’s what you need:


  • a radio or some sort of music player
  • a balloon
  • a mixing bowl
  • water
  • your parent’s permission


 
Download Student Worksheet & Exercises


1. Turn on your music player and turn it up fairly loud. (Tell your parents that it’s for science!)


2. Take a look at your speaker. You should be able to see it vibrating. If there’s a song with a lot of bass, you should really be able to see it moving.


3. Put your hand on the speaker. Can you feel the vibrations?


4. ASK YOUR PARENTS if you can carefully put a half-filled bowl of water on top of your speaker. You should be able to see the water vibrate.


Remember that sound is nothing more than vibrating molecules. All speakers do is get molecules of air to vibrate, creating longitudinal waves. They push air. Your eardrums vibrate just like the speakers do when the longitudinal waves of sound energy hit your ears.


How to Feel the Beat

1. Inflate the balloon. Get it fairly large.


2. Turn the music on loud (the more bass the better).


3. Put both hands lightly on the balloon.


4. Walk around the room holding the balloon lightly between your hands.


5. Try to feel the balloon vibrating.


6. Does the balloon vibrate more for low sounds or high sounds?


7. If you have a synthesizer (piano keyboard) you may want to try turning it up a bit and playing one note at a time. You should notice that the balloon vibrates more or less as you go up and down the musical scale. At very high notes, your balloon may not vibrate at all. We’ll talk more about why this happens later.


What’s causing the balloon to vibrate? Energy. Energy causes objects to move a distance against a force. The sound energy coming from the speakers is causing the balloon to vibrate. Your ear drums move in a very similar way to the balloon. Your ear drum is a very thin membrane (like the balloon) that is moved by the energy of the sound. Your ear drum, however, is even more sensitive to sounds than the balloon which is why you can hear sounds when the balloon is not vibrating. If you ear drum doesn’t vibrate, you don’t hear the sound.


What to do this experiment but no speakers?

Here’s another version of the same idea – I’ll bet you did this experiment when you were a small baby! You need: a mixing bowl (one of those metal bowls), something to hit it with ( a wooden spoon works well), and water.


1. Take the mixing bowl and put it on the table.


2. Smack it with the wooden spoon.


3. Listen to the sound.


4. Put your ear next to the bowl and try to hear how long the sound continues.


5. Now hit the bowl again.


6. Touch the bowl with your hand a second or two after you hit it. You should hear the sound stop. This is called dampening.


7. Now, for fun, fill the bowl with water up to an inch or so from the top.


8. Smack the bowl again and look very carefully at where the bowl touches the water.


9. When you first hit the bowl, you should see very small waves in the water.


I want you to notice two things here. Sound is vibration. When the bowl is vibrating, it’s making a sound. When you stop it from vibrating, it stops making sound. Any sound you ever hear, comes from something that is vibrating. It may have vibrated once, like a balloon popping. Or it may be vibrating consistently, like a guitar string.


The other thing I want you to notice is that you can actually see the vibrations. If you put water in the bowl, the tiny waves that are formed when you first hit the bowl are caused by the vibrating sides of the bowl. Those same vibrations are causing the sound that you hear.


item4mIf your mom’s worried about making a mess with water (and it’s not bath night tonight) then try this alternate experiment: you’ll need a mixing bowl, wooden spoon, and rubber bands.


1. Stretch a few rubber bands around the box or the bowl. If possible, use different thicknesses of rubber bands.


2. Strum the rubber bands.


3. Feel free to adjust how stretched the bands are. The more stretched, the higher the note.


4. Try plucking a rubber band softly.


5. Now pluck it fairly hard. The hard pluck should be louder.


Again I’d like you to notice three things here. Just like the last experiment, you should see that the sound is coming from the vibration. As long as the rubber band vibrates, you hear a sound. If you stop the rubber band from vibrating, you will stop the sound. Sound is vibration.


The second thing I’d like you to notice is that the rubber bands make different pitched sounds. The thinner the rubber band, or the tighter it’s stretched, the faster it vibrates. Another way to say “vibrating faster” is to say higher frequency. In sound, the higher the frequency of vibration, the higher the pitch of the note. The lower the frequency, the lower the pitch of the note. The average human ear can hear sound at as high a frequency as 20,000 Hz, and as low as 20 Hz. Pianos, guitars, violins and other instruments have strings of various sizes so that they can vibrate at different frequencies and make different pitched sounds. When you talk or sing, you change the tension of your vocal cords to make different pitches.


One last thing to notice here is what happened when you plucked the rubber band hard or softly. The rubber band made a louder noise the harder you plucked it right? Remember again that sound is energy. When you plucked that rubber band hard, you put more energy into it than when you plucked it softly. You gave energy (moved the band a distance against a force) to the rubber band. When you released the rubber band, it moved the air against a force which created sound energy. For sound, the more energy it has, the louder it is. Remember when we talked about amplitude a few lessons back? Amplitude is the size of the wave. The more energy a wave has the bigger it is. When it comes to sound, the larger the wave (the more energy it has) the louder it is. So when you plucked the rubber band hard (gave it lots of energy), you made a louder sound.


I said this in the beginning but I’ll repeat it here, hoping that now it makes more sense. When something vibrates, it pushes particles against a force (creates energy). These pushed particles create longitudinal waves. If the longitudinal waves have the right frequency and enough energy (loudness), your ear drum antennas will pick it up and your brain will translate the energy into what we call sound.


Exercises 


  1. What is sound?
  2. How does the rubber band make different sounds?
  3. What difference does it make how hard or soft you pluck the rubber bands?

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Humming Balloon

Sunday November 29, 2009

You can easily make a humming (or screaming!) balloon by inserting a small hexnut into a balloon and inflating. You can also try pennies, washers, and anything else you have that is small and semi-round. We have scads of these things at birthday time, hiding small change in some and nuts in the others so the kids pop them to get their treasures. Some kids will figure out a way to test which balloons are which without popping… which is what we’re going to do right now.


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Here’s what you need:


  • hexnut
  • balloon
  • your lungs


 
Download Student Worksheet & Exercises


What to do: Place a hexnut OR a small coin in a large balloon. Inflate the balloon and tie it. Swirl the balloon rapidly to cause the hexnut or coin to roll inside the balloon. The coin will roll for a very long time on the smooth balloon surface. At high coin speeds, the frequency with which the coin circles the balloon may resonate with one of the balloon’s “natural frequencies,” and the balloon may hum loudly.


Exercises


  1. How does sound travel?
  2. What is pitch?
  3. How is frequency related to pitch?

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Good Old Telephone

Sunday November 29, 2009

telephoneThis is the experiment that all kids know about… if you haven’t done this one already, put it on your list of fun things to do. (See the tips & tricks at the bottom for further ideas!)


We’re going to break this into two steps – the first part of the experiment will show us why we need the cups and can’t just hook a string up to our ear.  Are you ready?


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You need:


  • Table
  • Spoon (or whatever is handy)
  • Partner

1. Sit at a table.


2. Have your partner sit at the other end of the table.


3. Have your partner very lightly scratch the table with the spoon.


4. Listen to see if you can hear it.


5. While your partner is scratching, put your ear on the table. Do you hear a difference in the sound?


6. Switch roles so your partner gets a chance to try.


Did you notice how you could hear the soft spoon-scratching sound (I love a good alliteration) quite clearly when your head was on the table? The sound waves moved quickly through the table so they lost little of the loudness and quality of the original sound. When sound travels through the air, the sound energy gets dispersed (spread out) much more than through the table, so the sound does not travel as far nor as clearly. This next one is an oldie but a goodie!


A Couple Cups of Conversation


1. Using the scissors or a nail poke a hole in the middle of the bottom of both cups. Get an adult to help you with this. Since this isn’t biology, no bleeding allowed!


2. Thread an end of the string through the hole in the bottom of the cup and tie a big knot in it to keep it from sliding through the hole.


3. Do the same thing with the other cup so that when you are done you have a cup attached to both ends of the string.


4. Take one of the cups for yourself and hand the other cup to your partner. Walk apart from one another until the string is fairly taut.


5. Have your partner hold the cup up to his or her ear while you whisper into your cup.


6. Can your partner hear you? If not, see if you can stretch the string a little more.


7. Switch roles and try again.



The string being a solid and having tightly packed molecules allows the sound wave to move quickly and clearly through it. You can talk very quietly in one cup and yet your partner can still hear you fairly well.


Tips & Tricks

You can try different types of cups (foam, plastic, metal (like tin foil), paper…) and also change the sizes of the cups – is bigger or smaller better?  You can also change the connection between the cups – have you tried yarn, wool, string, nylon fishing line, rope, clothesline, or a braided combination?  You can also stick a slinky in place of the string of ‘space phones’.


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Seeing Sound Waves using Light

Sunday November 29, 2009

After you’ve completed this experiment, you can try making your own sound-to-light transformer as shown below. Using the properties of sound waves, we’ll be able to actually see sound waves when we aim a flashlight at a drum head and pick up the waves on a nearby wall.


Here’s what you need:


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  • empty soup can
  • balloon
  • small mirror
  • tape
  • scissors
  • hot glue gun
  • laser or flashlight


You will be adjusting the length of string of a pendulum until you get a pendulum that has a frequency of .5 Hz, 1 Hz and 2 Hz. Remember, a Hz is one vibration (or in this case swing) per second. So .5 Hz would be half a swing per second (swing one way but not back to the start). 1 Hz would be one full swing per second. Lastly, 2 Hz would be two swings per second. A swing is the same as a vibration so the pendulum must move away from where you dropped it and then swing back to where it began for it to be one full swing/vibration.


The following information is for students in our upper level part of the science program:


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“Advanced students: Download your Seeing Sound Waves using Light


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Thunder and Lightning

Sunday November 29, 2009

When there’s lightning, thunder is not far behind.  Even if you don’t live in a tropical thunderstorm area, you can still simulate this experiment using the variations below and get the most out of the main ideas about sound waves and light waves.


For starters, let’s assume you’re waiting for a good storm. When one’s brewing, grab a timer and a pencil with paper and wait inside the house near a window.


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Here’s what you need:


  • two hunks of wood or a pair of baseball bats
  • a neighborhood block
  • a partner

1. Wait until you see a lightning flash (do this indoors please!).


2. Start your timer (or count “one Mississippi, two Mississippi”, etc.)


3. Stop counting when you hear the thunder.


4. Take whatever number you’ve reached and divide it by 5. That number is how many miles the lightning strike is away from you. So if you’ve counted for about 3 seconds the lightning strike is about a half mile away. If you’ve counted for 5 seconds the lightning is 1 mile away. If you’ve counted for 8 seconds the lightning is about 1.5 miles away.


Remember, sound travels at about 1000 ft/sec. A mile is a little over 5000 feet (5280 ft. to be exact). So it takes sound about 5 seconds to go 1 mile!



 
“Advanced students: Download your Thunder and Lightning”


Want to do this experiment without a storm?

You’ll need two hunks of wood or a pair of baseball bats, a neighborhood block, and a partner.


1. Give your partner the two bats or hunks of wood.


2. Have them walk a half a block away or at least 250 feet.


3. When they get there have them clack together the two pieces of wood (be careful not to smash fingers, you want to hear the wood, not the scream of you friend!).


4. Have them do it several times. Try to notice a difference between when you see the wood crashing together and when you hear it. If you don’t hear a difference, get farther apart from one another.


5. Trade places so that your partner can see the delay of sound (just like on one of those old Japanese movies).


Sound travels at about 760 mph. That’s the same as about 1000 ft/sec. If your friend was standing about 250 feet away from you, it took a quarter of a second for the sound to get from your partner to you.


The next time you’re at a baseball game or a fireworks display try to time the difference between the time you see something and the time you hear something. Remember that sound travels 1000 ft/sec. If the distance is great enough you may be able to figure out how far away it is and amaze your friends!


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What is Frequency?

Sunday November 29, 2009

In this experiment you will be adjusting the length of string of a pendulum until you get a pendulum that has a frequency of .5 Hz, 1 Hz and 2 Hz. Remember, a Hz is one vibration (or in this case swing) per second. So .5 Hz would be half a swing per second (swing one way but not back to the start). 1 Hz would be one full swing per second. Lastly, 2 Hz would be two swings per second. A swing is the same as a vibration so the pendulum must move away from where you dropped it and then swing back to where it began for it to be one full swing/vibration.


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You’ll need:


  • 3 Foot Long String
  • A Weight that can be tied to the end of the string
  • A Timer or Stopwatch
  • Masking Tape
  • A Table or Chair
  • A Partner is helpful


 


“Advanced students: Download your What is Frequency?”


1. Tie your weight (the official name of the weight on the end is bob. Personally I’ve always preferred the name Shirley, but Bob it is.) to the end of the 3 foot string. If you’ve done the gravity lesson in the Mechanics set of lessons you’ll remember that the weight of the bob doesn’t matter. Gravity accelerates all things equally, so your pendulum will swing at the same speed no matter what the weight of the bob.


2. Tape the string to a table or chair or door jam. Make sure it can swing freely at about 3 feet of length.


3. I would recommend starting with 1 Hz. It tends to be the easiest to find. Then try .5 Hz and then 2 Hz.


4. The easiest way I’ve found to do this is to start the pendulum swinging and at the same time start the timer. Count how many swings you get in ten seconds.


5. Now, adjust the string. Make it longer or shorter and try again. When you get 10 swings in 10 seconds you got it! That’s one swing per second. You should be able to get quite close to one swing per second which is 1 Hz.


6. Now try to get .5 Hz. In this case you will get 5 swings in ten seconds when you find it. (A little hint, the string is pretty long here.)


7. Now speed things up a bit and see if you can get 2 Hz. Be prepared to count quick. That’s 2 swings a second or 20 swings in 10 seconds! (Another little hint, the string is quite short for this one.)


Did you get all three different frequency pendulums? It takes a while but my classes found it rather fun. You’ve created three different frequencies. 2 Hz being the fastest frequency. That was pretty fast right? Can you imagine something going at 10 Hz? 100 Hz? 1,000,000 Hz? I told you things were moving at outrageous speeds!


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Ear Tricks

Sunday November 29, 2009

Think of your ears as ‘sound antennas’.  There’s a reason you have TWO of these – and that’s what this experiment is all about.  You can use any noise maker (an electronic timer with a high pitched beep works very well), a partner, a blindfold (not necessary but more fun if you have one handy), and earplugs (or use your fingers to close the little flap over your ear – don’t stick your fingers IN your ears!).


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Here’s what you need:


  • noisemaker
  • partner
  • you
  • blindforld
  • earplugs


 
Download Student Worksheet & Exercises


1. Sit or stand in the middle of a room.


2. Close your eyes or put on the blind fold.


3. Have your partner walk to another part of the room as quietly as possible.


4. Have your partner make the noisemaker make a noise.


5. With your eyes still closed, point to where you think the sound came from.


6. Try it several times and then let your partner have a turn.


How well did you do? Probably pretty well. Your ears are very good at determining where sounds are coming from. The reason your ears are so good at detecting the direction of a sound is due to the fact that sound hits one ear slightly before it hits the other ear. You brain does an amazing bit of quick math to make its best guess as to where the sound is coming from and how far away it is. Let’s do a little more with this.


1. Sit or stand in the middle of a room.


2. Close your eyes or put on the blindfold.


3. Have your partner walk to another part of the room as quietly as possible.


4. Have you partner move the sound maker around the room like before, but this time make sure your partner makes the sound directly in front of you, behind you and over your head as well.


5. With your eyes still closed, point to where you think the sound came from.


6. Try it several times and then let your partner have a turn.


Did you get fooled this time? This works sometimes, but not always. What I hope happened was when the noisemaker was above your head, directly in front of you or directly behind you, you had trouble determining where the sound was coming from. Can you guess why this might have happened? Your ears are placed directly across from one another. If a noise happens directly in front of you, it hits your both ears at the exact same time. Your brain has no clues as to where the sound is coming from if the sound hits both ears at the same time so it makes its best guess. In this case, its best guess may be wrong. Let’s try one more thing here.


1. Sit or stand in the middle of a room.


2. Close your eyes or put on the blindfold.


3. Put an ear plug in one of your ears. If you don’t have one, use your finger to cover your ear. Be very careful not to put your finger into your ear. Just use your finger to cover the hole in your ear.


4. Have your partner walk to another part of the room as quietly as possible.


5. Have your partner make the noisemaker make a noise. This will work best if the noise is not too loud.


6. With your eyes still closed, point to where you think the sound came from.


7. Try it several times and then let your partner try to find the sound.


How did you do with just one ear? Did you get fooled a little more often this time? Your brain has fewer clues to work with so it does the best it can with what it has.


Exercises 


  1. How do your two ears work together to determine the location of a sound?
  2. Does it matter what frequency (how high or low) the sound is? Are some frequencies easier to detect than others with only one ear?

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Chladni Plates

Sunday November 29, 2009

chladniThis experiment is just for advanced students. Ernst Florens Friedrich Chladni (1756-1827) is considered to be the ‘father of acoustics’. He was fascinated by vibrating things like plates and gases, and his experiments resulted in two new musical instruments to be developed.


When Chladni first did these vibrating plate experiments (as shown in the video below), he used glass plates instead of metal. He was also one of the first to figure out how to calculate the speed of sound through a gas.


And it will completely blow your mind. Chladni patterns are formed with a metal plate covered in regular table salt is vibrated through different frequencies.


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Here’s what you need:


  • metal plate or un-rimmed cookie sheet (thinner is better, but you’ll have to experiment with this)
  • violin rosin
  • bass fiddle bow
  • two containers of salt

There are different ways of vibrating the plate – the easiest is by banging it, but this gives you only one frequency and usually makes a mess of the salt. You can alternatively bow the edge of the plate (clamped to a table) with a bass fiddle bow and specific points to get various frequencies… but you will need to practice to get this method to work.


These patterns can also be formed by setting the metal plate on a mechanical driver (like a speaker) controlled by a signal generator. (This way you don’t have to practice your bowing!).  The patterns you get this way are different from the bowing patterns, since you are vibrating it from the center instead of the edge.


chladniarray
Image Source: UCLA Physics Dept.


These patterns were made by attaching the center of the plate firmly to a speaker.  In the video below, you’ll see how the different patterns were made in a live physics demo from the physics department at WFU:



 


Tell us what you think! Write a comment below…


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Transverse and Longitudinal Waves

Sunday November 29, 2009

Since we can’t see soundwaves as they move through the air, we’re going to simulate one with rope and a friend. This will let you see how a vibration can create a wave. You’ll need at least 10 feet of rope (if you have 25 or 50 feet it’s more fun), a piece of tape (colored if you have it), a slinky, and a partner. Are you ready?


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1. Give one end of the rope to your partner.


2. Stretch the rope out so that it is a bit slack.


3. Now move your hand up and down. Feel free to do it several times in a row. Your partner should keep his or her hands as still as possible.


4. Watch the waves move from your hand to the other end of the rope.


5. Now let your partner create waves.


6. If you wish, you can try to time your vibrations and create waves with specific frequencies. A frequency of one Hertz is fairly easy to do (one rope shake per second). Can you create rope waves of higher frequencies? You may find that your arm gets tired pretty quickly!


Your hand is the vibrating particle. As your hand vibrated up and down, you moved the particles of the rope up and down. As those particles of rope vibrated, they vibrated the particles next to them. As they vibrated, they vibrated the particles next to them and so on and so forth. So the wave moved from your hand across the room. Did your hands move across the room. Nope, but the wave you created with your vibrating hand did.


This is the way energy travels. Why is the rope wave energy? Because the particles moved a distance against a force. Work was done on the particles. In fact, when you shook the rope, your energy from your body moved across the room with the wave and was transferred (moved to) your partner. Your partner’s hands could feel the energy you put into the rope in the first place. The work you did on the rope was transferred by the rope wave and did work on your partners hand. You have moved energy across the room!


Now… let’s add another element to this experiment…


Transverse Waves

1. Put a piece of (colored if possible) tape in about the middle of the rope.


2. Tie your rope to something or let your friend hold on to one end of it.


3. Now pull the rope so that it is a bit slack but not quite touching the floor.


4. Vibrate your arm. Move your arm up and down once and watch what happens.


5. Now, vibrate your arm a bunch of times (not too fast) and see the results. Notice the action of the tape in the middle of the rope.


transvWhat you’ve done is create a transverse wave. With a transverse wave, if the particle (in this case your hand) moves up and down, the wave will move to the left and/or right of the particle. The word perpendicular means that if one thing is up and down, the other thing is left and right. A transverse wave is a wave where the particle moves perpendicular to the medium. The medium is the material that’s in the wave. The medium in this case is the rope.


For example, in a water wave, the medium is the water. Your hand moved up and down, but the wave created by your hand moved across the room, not up. The wave moved perpendicular to the motion of your hand. Did you take a look at the tape? The tape represents a particle in the wave. Notice that it too, was going up and down. It was not moving along the wave. In any wave the particles vibrate, they do not move along the wave.


Longitudinal Waves

Now that you’ve seen a transverse wave, let’s take a look at a longitudinal wave. Here’s what you do:


1. Put a piece of tape on one slinky wire in the middle or so of the slinky.


2. Let your friend hold on to one end of the slinky or anchor the slinky to a chair or table.


3. Now stretch the slinky out, but not too far.


4. Quickly push the slinky toward your friend, or the table, and then pull it back to its original position. Did you see the wave?


5. Now do it again, back and forth several times and watch where the slinky is bunched up and where it’s spread out.


6. Notice the tape. What is it doing?


longitudinalHere you made a longitudinal wave. A longitudinal wave is where the particle moves parallel to the medium. In other words, your hand vibrated in the same direction (parallel to the direction) the wave was moving in. Your vibrating hand created a wave that was moving in the same direction as the hand was moving in. Did you take a look at the tape? The tape was moving back and forth in the same direction the wave was going.


Do you see the difference between a transverse wave and a longitudinal wave? In a transverse waves the particles vibrate in a different direction (perpendicular) to the wave. In a longitudinal wave the particles vibrate in the same direction (parallel) to the wave.


What’s the Difference between Amplitude and Wavelength?

Here’s an easy way to get a feel for amplitude:


1. Put a piece of tape in about the middle of the rope.


2. Tie your rope to something or let your friend hold on to one end of it.


3. Now pull the rope so that it is a bit slack but not quite touching the floor.


4. Your friend should hold their hands as still as possible.


5. Vibrate your hand but only move it up and down about a foot or so. Have your partner pay attention to how that feels when the wave hits him or her.


6. Now, vibrate your hand but now move it up and down 2 or 3 feet. How does that feel to your partner?


7. Have your partner do the vibrating now and see what you feel.


You created two different amplitude waves. The first wave had a smaller amplitude than the second wave. What you and your partner should have felt was more energy the second time. The wave should have hit your hand with more energy when the wave had more amplitude.


Here’s a great way to visualize wavelength:


1. Tie your rope to something or let your friend hold on to it.


2. Now pull the rope so that it is a bit slack but not quite touching the floor.


3. Your friend should hold their hands as still as possible.


4. Now begin vibrating your hand fairly slowly. In this case, it works better if you move your hand in a circle.


5. Try to make a wavelength with the rope. In other words it will look like you’re playing jump rope.


6. Now try a one and a half wavelengths.


7. Can you get two or more wavelengths? You’ve really got to get your hand moving to get it.


waves


In this image, the left wave is ONE wavelength, the middle is 1.5 wavelegnths, and the right is TWO wavelengths.  See the difference?


Did you notice how the frequency of your hand determined the wavelength of the rope? The faster your hand, moved the more wavelengths you could get.
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How a Record Player Works

Sunday November 29, 2009

Before CDs, there were these big black discs called records. Spinning between 33 and 45 times per minute on a turntable, people used to listened to music just like this for nearly a century. Edison, who had trouble hearing, used to bite down hard on the side of his wooden record player (called a phonograph) and “hear” the music as it vibrated his jaw.


Many people today still think that records still sound better than CDs (I think they do), especially if the record is well cared for and their players are tuned just right. Here’s a video on how a record works:


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Here’s what you need:


  • an old turntable (do you have one in your garage?)
  • old record that can be scratched
  • tack
  • plastic container, like a clean yogurt or butter tub

If you have an old turntable and OLD record that can be scratched, here’s how to listen to the music without using regular speakers!



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Building Speakers

Sunday November 29, 2009

Alexander Graham Bell developed the telegraph, microphone, and telephone back in the late 1800s. We'll be talking about electromagnetism in a later unit, but we're going to cover a few basics here so you can understand how loudspeakers transform an electrical signal into sound.

This experiment is for advanced students.We'll be making different kinds of speakers using household materials (like plastic cups, foam plates, and business cards!), but before we begin, we need to make sure you really understand a few basic principles. Here's what you need to know to get started:

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For this experiment to really make sense, you'll need to complete the Telephone and the Seeing Sound Waves Experiments first. This will cover the basic mechanics of sound vibrations and waves.

Let's talk about the telegraph. A telegraph is a small electromagnet that you can switch on and off. The electromagnet is a simple little thing made by wrapping insulated wire around a nail. An electromagnet is a magnet you can turn on and off with electricity, and it only works when you plug it into a battery.

Anytime you run electricity through a wire, you also get a magnetic field. You can amplify this effect by having lots of wire in a small space (hence wrapping the wire around a nail) to concentrate the magnetic effect. The opposite is true also - if you rub a permanent magnet along the length of the electromagnet, you'll get an electric current flowing through the wire. Magnetic fields cause electric fields, and electric fields cause magnetic fields. Got it?

A microphone has a small electromagnet next to a permanent magnet, separated by a thin space. The coil is allowed to move a bit (because it's lighter than the permanent magnet). When you speak into a microphone, your voice sends sound waves that vibrate the coil, and each time the coil moves, it causes an electrical signal to flow through the wires, which gets picked up by your recording system.

A loudspeaker works the opposite way. An electrical signal (like music) zings through the coil (which is also allowed to move and attached to your speaker cone), which is attracted or repulsed by the permanent magnet. The coil vibrates, taking the cone with it. The cone vibrates the air around it and sends sounds waves to reach your ear.

If you placed your hand over the speaker as it was booming out sound, you felt something against your hand, right? That's the sound waves being generated by the speaker cone. Each time the speaker cone moves around, it create a vibration in the air that you can detect with your ears. For deep notes, the cone moves the most, and a lot of air gets shoved at once, so you hear a low note. Which is why you can blow out your speakers if your base is cranked up too much. Does that make sense?

Here's a video to help make sense of all these ideas. One of our scientists, Al, is going to demonstrate how to use a signal generator to drive a speaker at different frequencies. We even brought in specialist (with very good hearing!) to detect the full range of sound and used a special microphone during recording, so you should hear the same thing we did during the testing.

Download Student Worksheet & Exercises

How to Build a Speaker

Here's what you need:

  • Plates or cups made of foam, paper or plastic
  • Sheet of copy paper
  • 3 business cards
  • Magnet wire AWG 28, 30 or 32 
  • 2-4 neodymium or similar (rare earth) magnets
  • Index cards or stiff paper
  • Plastic disposable cup
  • Tape
  • Hot glue gun
  • Scissors
  • 1 audio plug or other cable that fits into your stereo / mp3 player
  • 2 alligator clip wires

Now you're ready to make your speakers. Note that these speakers are made from cheap materials and are for demonstration purposes only... they do not have an amplifier, so you'll need to place your ear close to the speaker to detect the sound. DO NOT connect these speakers up to your iPOD or other expensive stereo equipment, as these speakers are very low resistance (less than 2 ohms) and can damage your sound equipment if you're not careful. The best source of music for these speakers is an old boom box with a place to plug in your headphones. We'll show you everything in this video:

Sound waves can affect liquids also! Here’s what happens if you run sound waves through a non-newtonian cornstarch solution:

Exercises 

  1. Does it matter how strong the magnets are?
  2. What else can you use besides a foam plate?
  3. Which works better: a larger or smaller magnet wire coil?
  4. How can you detect magnetic fields?
  5. How does an electromagnet work?
  6. How does your speaker work?
  7. Is a speaker the same as a microphone?
  8. Does the shape and size of the plate matter? What if you use a plastic cup?

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Unit 6: Sound Waves (Resonance) Video

Sunday November 29, 2009

This lesson, I’d like to take the concepts of frequency and vibration just a bit further and talk about natural frequency and resonance. Are you ready?



Here’s the video for the Tacoma Narrows Bridge (this is the actual video shown to the public at the time):





Unit 6: Sound Waves (Vibrations) Video

Sunday November 29, 2009

Energy moves in waves. Before we get in over our heads talking about sound waves, though, we need to spend some time on this vibration thing. This lesson we will be taking a careful look at vibration and frequency.



Advanced High School Course in Radio Astronomy

Sunday November 22, 2009
Radio antenna dishes of the Very Large Array radio telescope in New Mexico.
Radio antenna dishes of the Very Large Array radio telescope in New Mexico.

This experiment is for advanced students. Radio astronomy is the study of radio waves originating outside the Earth. The radio range of frequencies or wavelengths is loosely defined by three factors: atmospheric transparency, current technology, and fundamental limitations imposed by quantum noise. Together they yield a boundary between radio and far-infrared astronomy at frequency 1 THz (1 THz =1012 Hz) or wavelength =0.3 mm.


If you’re an advanced high school-age student with a yearning to learn more about radio astronomy, you’re in the right place. First, you’ll get a college-level course about the fundamentals of radio astronomy with a full textbook, and you’ll also find problem sets with solutions and also a final exam.The lab included will have you building your very own radio telescope for under $100. Feel free to build the telescope as you work through the text or straight off the bat. If you’re allergic to math, just skip over those sections to get at the really interesting stuff. Click here to download the full text or use the links below.


Shopping List for Unit 9

Sunday November 15, 2009

How many of these items do you already have? We've tried to keep it simple for you by making the majority of the items things most people have within reach (both physically and budget-wise), and even have broken down the materimoals by experiment category so you can decide if those are ones you want to do. You do not need to do ALL the experiments - just pick the ones you want to do!

Don’t be afraid of this list! The materials are broken down by availability and expense. The items in the first list are low-cost materials you already have or can easily add to your next grocery store list. The second list includes mid-priced equipment for more in-depth projects, and the last list of items is appropriate for upper grades. We’ll be re-using the specialty items from this list (like lenses, lights, lasers, and electrical components) for future projects.

Shopping List for Unit 9: Light Waves Click here for Shopping List for Unit 9.

NOTE: Radio Shack part numbers have been replaced. Click here for full chart.

Light Waves

  • Water glass
  • Clean pickle jar
  • Cooking oil, such as canola (approx. 4 cups – use a cheap brand)
  • Two pennies, dollar bill
  • Flashlight
  • 1 teaspoon of milk (soy, cow…) OR white flour
  • 2 hand held magnifying lenses
  • Old CD you can scratch (used in two experiments)
  • Paper towel tube
  • Feather (any size)
  • Index cards
  • Crayons
  • Bar of Ivory soap (get a pack of 3)
  • Sharp pencil
  • String (about 3’)
  • Scissors, tape
  • Television with a remote control
  • Ziploc bag full of water
  • Black plastic trash bag
  • Piece of plastic (like a plastic spoon or cup)
  • Metal pot or pan (not Teflon coated)
  • Clean piece of white paper
  • UV beads
  • Sunblock
  • Sunglasses
  • Two pairs of sunglasses (the polarizing kind rated for UV protection work well)

Light Waves Part 2

  • Small box with lid (like a shoe box)
  • Tracing paper (1 sheet)
  • Microwave
  • BIG bar of Hershey’s chocolate (any type)
  • Water in a shallow glass baking dish
  • Mirror (like a hand mirror from the bathroom)
  • Optional: UV Fluorescent Black Light
  • 2 yardsticks (AKA meterstick)
  • 10-20 popsicle sticks
  • Index cards or pieces of cardboard
  • Set of lenses with extra double-convex  lenses (this is the kind in a hand-held magnifying glass). Pick one of these to get as an extra, or get all 4: 50mm, 150mm, 300mm, 500mm) ...OR… instead of buying lenses, simply use eyeglasses and magnifiers that you already have around the house.
  • Optional: if you want to make the Newtonian telescope, then pick up a concave mirror AND a small mirror (like a mosiac mirror from the craft store, or mirror from a compact).
  • Diffraction grating (you can use an old CD in a pinch)
  • Sheet of mylar (5” x 8” or larger) and cardboard OR use three rectangular mirrors approx. 8” x 1”
  • Scissors, tape
  • Optional: wooden clothespins (about 4)
  • Optional: red, green, and blue colored light sticks (Make sure the light inside the red stick really glows RED, not the usual green liquid enclosed in a red-colored tube.)
  • For the last few items on this list, you can select from either group:

Group A: Three flashlights, three colors of nail polish (red, green, and blue), clear tape (or plastic wrap) OR…

Group B: Three ‘party bulb’ lights (green, blue, and red colored incandescent light bulbs) in clip-on lamps

Lasers

  • Red laser pointer (NOT GREEN!)
  • Small mirrors (mosaic mirrors are cheapest)
  • 3 large paper clips
  • 3 brass fasteners
  • 5 index cards
  • 2 pins
  • 2 razor blades
  • 4 clothespins
  • Scissors, tape
  • White wall (or white paper stuck to the wall)
  • PLUS materials from Light Waves 1 & 2

For Advanced Students:

 

Laser Light Show

  • Red laser pointer
  • 2 3VDC motors
  • 2 gears** or corks (you’ll need a solid way to attach the mirror to the motor shaft tip)
  • 2 1” round mirrors (use mosaic mirrors)
  • 2 DPDT switches with center off
  • 20 alligator clip leads
  • 2 AA battery packs with 4 AA batteries
  • 2 1K or 5K-ohm potentiometers
  • Zip-tie (from the hardware store)
  • ½ " or ¾ " metal conduit hangers (size to fit your motors from the hardware store)
  • 3 sets of ¼ " x 2" bolts, nuts, and washers
  • 1 tupperware container (at least 7” x 5”) with lid
  • Basic tools (scissors, hot glue gun, drill, wire strippers, pliers, screwdriver)

**If you have trouble finding these parts (with the ** next to them), just send us an email.

 

 

Laser Communicator

This project requires soldering. We’ll teach you how to solder, but you need a soldering iron. If you don’t have a soldering iron, save this project for another time.

 

 

 


Kinetic Energy Exercises

Saturday November 7, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.


Some of these questions you might recognize from the last lesson on potential energy, but we put them here again so you can see how they are inter-related. Have fun!


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1. What is potential energy?


2. What is kinetic energy?


3. What is gravitational potential energy?


4. What does transfer of energy mean?


5. What is conservation of energy?


************************************


6. Describe the potential and kinetic energy of this roller coaster:


rcp1


7. Where is the potential energy greatest?


8. Where is the kinetic energy greatest?


9. Where is potential energy lowest?


10. Where is kinetic energy lowest?


11. Where is KE increasing, and PE is decreasing?


12. Where is PE increasing and KE decreasing?


**************************************


13. What’s energy efficiency?


14. Which is more energy efficient, a nice new Hot Wheel car or one that’s been stepped on?


15. In most systems, where are the most common two sources of non-useful energy?


16. What is work?


17. What does a Newton measure?


18. What does a Joule measure?


************************************


For Advanced Students:

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Gravitational Potential Energy PE=mgh: m is mass, g is 10m/s2 (32 ft/s2), and h is height.


19. Timmy is sitting 3 m (9 feet) up in a tree holding a 1 kg (about 2 pound) snowball. What’s the gravitational potential energy of the snowball?


20. Susie is now standing under the tree. The distance between the snow ball and the top of Susie’s head is 2m. What’s the potential energy of the snow ball if it was to be dropped on Susie’s head?


21. What is the kinetic energy that the snowball has just before it hits Susie?
(No math needed here, just think about it for a second.)


Kinetic energy = 1/2 mv2 m is mass and v is velocity.


22. What is the kinetic energy of a 680 kg (1300 lb.) car traveling at 13 m/s (30 mph)?


23. What is the kinetic energy of a 680 kg car traveling at 26 m/s (60 mph)


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Need answers?
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Answers to Kinetic Energy Exercises

Saturday November 7, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for K-8 and here for K-12.


Answers:
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1. Potential energy is the energy that something has that can be released.


2. Kinetic energy is the energy of motion. KE = 1/2 mv2


3. Gravitational potential energy is the energy something has due to gravity. Gravitational Potential Energy = mgh.


4. Energy can be changed from one form to another and from one object to another.


5. In a closed system energy can neither be created or destroyed.


6. See below…


7. Potential energy is greatest at a. The coaster is at it’s highest point above the ground.


8. Kinetic Energy is the greatest at c. The coaster is going the fastest at this point.


9. Potential energy is lowest at c. The coaster is as low as it can get.


10. Kinetic energy is lowest at a. The coaster is not moving.


11. KE is increasing and PE is decreasing at b. The coaster is losing height so it’s losing PE but it is gaining speed so it is gaining KE.


12. PE is increasing and KE is decreasing at d. The coaster is getting higher so it’s gaining PE but it’s losing speed so it’s losing KE.


13. Energy efficiency is how much energy in a system is transferred to useless energy.


14. It depends on what you want the car to do! If you want the car to go far after leaving the track you want the brand new one. It will have less of the original potential energy transferred to heat since it will have less friction. However, if you want your car to generate heat, you want the stepped on one. It will have much more of its energy transferred to heat due to its high friction! (In other words, you need to be a bit careful with the term “useful” energy)


15. Sound energy and heat energy. Heat comes from the force of friction. Sound energy, as a matter of fact, also gets transferred to heat energy.


16. Work is defined as moving an object over a distance against a force. Work = force x distance


17. A Newton is a unit of force. How much force it takes to push or pull something. It takes about one Newton of force to lift an apple.


18. A Joule is a unit of energy. It takes one Joule to exert one Newton of force over a distance of one meter.


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Answers for Advanced Students:

19. PE = mgh
PE = 1 kg x 10 m/s2 ft/s2 x 3m
PE = 30 Joules


20. PE = mgh
PE = 1 kg x 10 m/s2 x 2m
PE = 20 Joules (Don’t worry, since the snowball falls apart very little of the energy actually gets transferred to poor Susie.)


21. 20 Joules. All the potential energy that the snowball started with becomes kinetic energy by the time it hits Susie.


22. KE = 1/2 mv2
KE = 1/2 680 kg x (13m/s)2
KE = 340 kg x 169
KE = 57460 Joules (WOW!)


23. KE= 1/2 mv2
KE =1/2 680 x 262
KE = 340 x 676
KE = 229,840 Joules (WOW WOW)


This is an important point. As the speed of something doubles, its kinetic energy squares! This is why it is very important to not speed in a car. An increase in speed quickly increases the potentially dangerous kinetic energy.


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Potential Energy Exercises

Saturday November 7, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
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1. What is potential energy?


2. What is gravitational potential energy?


3. Where is the potential energy greatest?


4. Where is potential energy lowest?


5. Give an example of where potential energy decreases.


6. What is work?


7. What does a Newton measure?


8. What does a Joule measure?


Need answers?


[/am4show]


Answers to Potential Energy Exercises

Saturday November 7, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for K-8 and here for K-12.


Answers:
[am4show have=’p8;p9;p15;p42;’ guest_error=’Guest error message’ user_error=’User error message’ ]
1. Potential energy is the energy that something has that can be released.


2. Gravitational potential energy is the energy something has due to gravity. Gravitational Potential Energy = mgh


3. Potential energy is greatest when a heavy object is up high, like a bowling ball falling from an airplane.


4. Potential energy is lowest at the surface of the Earth. The object is as low as it can get.


5. Potential energy decreases as an object falls to the Earth.


6. Work is defined as moving an object over a distance against a force. Work = force x distance


7. A Newton is a unit of force. How much force it takes to push or pull something. It takes about one Newton of force to lift an apple.


8. A Joule is a unit of energy. It takes one Joule to exert one Newton of force over a distance of one meter.


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Catapults

Saturday November 7, 2009

When you drop a ball, it falls 16 feet the first second you release it. If you throw the ball horizontally, it will also fall 16 feet in the first second, even though it is moving horizontally… it moves both away from you and down toward the ground. Think about a bullet shot horizontally. It travels a lot faster than you can throw (about 2,000 feet each second). But it will still fall 16 feet during that first second. Gravity pulls on all objects (like the ball and the bullet) the same way, no matter how fast they go.

What if you shoot the bullet faster and faster? Gravity will still pull it down 16 feet during the first second, but remember that the surface of the Earth is round. Can you imagine how fast we’d need to shoot the bullet so that when the bullet falls 16 feet in one second, the Earth curves away from the bullet at the same rate of 16 feet each second?

Answer: that bullet needs to travel nearly 5 miles per second. (This is also how satellites stay in orbit – going just fast enough to keep from falling inward and not too fast that they fly out of orbit.)

Catapults are a nifty way to fire things both vertically and horizontally, so you can get a better feel for how objects fly through the air. Notice when you launch how the balls always fall at the same rate – about 16 feet in the first second.  What about the energy involved?

When you fire a ball through the air, it moves both vertically and horizontally (up and out). When you toss it upwards, you store the (moving) kinetic energy as potential energy, which transfers back to kinetic when it comes whizzing back down. If you throw it only outwards, the energy is completely lost due to friction.

The higher you pitch a ball upwards, the more energy you store in it. Instead of breaking our arms trying to toss balls into the air, let's make a simple machine that will do it for us. This catapult uses elastic kinetic energy stored in the rubber band to launch the ball skyward.

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Here's what you need:

  • 9 tongue-depressor size popsicle sticks
  • four rubber bands
  • one plastic spoon
  • ping pong ball or wadded up ball of aluminum foil (or something lightweight to toss, like a marshmallow)
  • hot glue gun with glue sticks

Download Student Worksheet & Exercises

catapult1What’s going on? We’re utilizing the “springy-ness” in the popsicle stick to fling the ball around the room. By moving the fulcrum as far from the ball launch pad as possible (on the catapult), you get a greater distance to press down and release the projectile. (The fulcrum is the spot where a lever moves one way or the other – for example, the horizontal bar on which a seesaw “sees” and “saws”.)

Troubleshooting: These simple catapults are quick and easy versions of the real thing, using a fulcrum instead of a spring so kids don’t knock their teeth out. After making the first model, encourage kids to make their own “improvements” by handing them additional popsicle sticks, spoons, and glue sticks (for the hot glue guns).

If they get stuck, you can show them how to vary their models: glue a second (or third, fourth, or fifth) spoon onto the first spoon for multi-ammunition throws, increase the number of popsicle sticks in the fulcrum from 7 to 13 (or more?), and/or use additional sticks to lengthen the lever arm. Use ping pong balls as ammo and build a fort from sheets, pillows, and the backside of the couch.

 

Want to make a more advanced catapult? 

This catapult requires a little more time, materials, and effort than the catapult design above, but it's totally worth it. This device is what most folks think of when you say 'catapult'. I've shown you how to make a small model - how large can you make yours?

This project lends itself well to taking data and graphing your results: you and your child can jot down the distance traveled along with time aloft with further calculations for high school students for velocity and acceleration. My university students would also calculate statistics, percent error, and more. My students also mapped out the material properties of the 'cantilevered beam' as well as model the popsicle stick as a spring (to determine the spring constant (k) for your calculations from Hooke's Law). You can take this project as far as you want, depending on the interest and ability of kids.

Materials:

  • plastic spoon
  • 14 popsicle sticks
  • 3 rubber bands
  • wooden clothespin
  • straw
  • wood skewer or dowel
  • scissors
  • hot glue gun

Try different ball weights (ping pong, foil crumpled into a ball, whiffle balls, marshmallows, etc) and chart out the results: make a data table that shows what ball you tried and how far it went. You can also use a stopwatch to time how long your ball was in the air.

You can also graph your results: make a chart where you plot each data point on a graph that has distance on the vertical axis and time on the horizontal axis.

Advanced Teaching Tips: For high school and college-level physics classes, you can easily incorporate these launchers into your calculations for projectile motion. Offer students different ball weights (ping pong, foil crumpled into a ball, and whiffle balls work well) and chart out the results.

Exercises Answer the questions below:

  1. How is gravity related to kinetic energy?
    1. Gravity creates kinetic energy in all systems.
    2. Gravity explains how potential energy is created.
    3. Gravity pulls an object and helps its potential energy convert into kinetic energy.
    4. None of the above
  2. If you could use your catapult to launch your ball of foil into orbit, how high would it have to go?
    1. Above the atmosphere
    2. High enough to slingshot around the moon
    3. High enough so that when it falls, the earth curves away from it
    4. High enough so that it is suspended in empty space
  3. Where is potential energy the greatest on the catapult?

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Potato Cannon

Saturday November 7, 2009

This experiment is for Advanced Students.There are several different ways of throwing objects. This is the only potato cannon we’ve found that does NOT use explosives, so you can be assured your kid will still have their face attached at the end of the day. (We’ll do more when we get to chemistry, so don’t worry!)


These nifty devices give off a satisfying *POP!!* when they fire and your backyard will look like an invasion of aliens from the French Fry planet when you’re done. Have your kids use a set of goggles and do all your experimenting outside.


Here’s what you need:


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  • potatoes
  • an acrylic tube (clear is best so you can see what’s happening inside!)
  • wooden dowel
  • washer (this is your ‘hand-saver’)


Where is the potential energy the greatest? How much energy did your spud have at this point? Hmmm… let’s see if we can get a few actual numbers with this experiment. In order to calculate potential energy at the highest point of travel, you’ll need to figure out how high it went.


Here are instructions for making your own height-gauge:



Once you get your height gauge working right, you’ll need to track your data. Start a log sheet in your journal and jot down the height for each launch. Let’s practice a sample calculation:


If you measured an angle of 30 degrees, and your spud landed 20 feet away, we can assume that the spud when highest right in the middle of its flight, which is halfway (10 feet). Use basic trigonometry to find the height 45 degrees up at a horizontal distance ten feet away to get:


height = h = (10′) * (tan 30) = 5.8 feet
(Convert this to meters by: (5.8 feet) * (12 inches/foot) / (39.97 inches/meter) = 1.8 meters)

I measured the mass of my spud to be 25 grams (which is 0.025 kg).


Now, let’s calculate the potential energy:


PE = mgh = (0.025 kg) * (1.8 meters) * (10 m/s2) = 0.44 Joules


How fast was the spud going before it smacked into the ground? Set PE = KE to solve for velocity:


mgh = 0.5 mv2 gives v = (2gh)1/2


Plug in your numbers to get:


v = [(2) * (10) * (1.8)]2 = 6 m/s (or about 20 feet per second). Cool!


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P-Shooters

Saturday November 7, 2009

This is a simple, fun, and sneaky way of throwing tiny objects. It’s from one of our spy-kit projects. Just remember, keep it under-cover. Here’s what you need:


  • a cheap mechanical pencil
  • two rubber bands
  • a razor with adult help

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Advanced students: Download your P-Shooter Lab here.


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Bobsleds

Saturday November 7, 2009

Bobsleds use the low-friction surface of ice to coast downhill at ridiculous speeds. You start at the top of a high hill (with loads of potential energy) then slide down a icy hill til you transform all that potential energy into kinetic energy.  It’s one of the most efficient ways of energy transformation on planet Earth. Ready to give it a try?


This is one of those quick-yet-highly-satisfying activities which utilizes ordinary materials and turns it into something highly unusual… for example, taking aluminum foil and marbles and making it into a racecar.


While you can make a tube out of gift wrap tubes, it’s much more fun to use clear plastic tubes (such as the ones that protect the long overhead fluorescent lights). Find the longest ones you can at your local hardware store. In a pinch, you can slit the gift wrap tubes in half lengthwise and tape either the lengths together for a longer run or side-by-side for multiple tracks for races. (Poke a skewer through the rolls horizontally to make a quick-release gate.)


Here’s what you need:


  • aluminum foil
  • marbles (at least four the same size)
  • long tube (gift wrapping tube or the clear protective tube that covers fluorescent lighting is great)

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bobsledsIf you’re finding that the marbles fall out before the bobsled reaches the bottom of the slide, you need to either crimp the foil more closely around the marbles or decrease your hill height.


Check to be sure the marbles are free to turn in their “slots” before launching into the tube – if you’ve crimped them in too tightly, they won’t move at all. If you oil the bearings with a little olive oil or machine oil, your tube will also get covered with oil and later become sticky and grimy… but they sure go faster those first few times!



 
Download Student Worksheet & Exercises


Exercises Answer the questions below:


  1. Potential energy is energy that is related to:
    1. Equilibrium
    2. Kinetic energy
    3. Its system
    4. Its elevation
  2. If an object’s energy is mostly being used to keep that object in motion, we can say it has what type of energy?
    1. Kinetic energy
    2. Potential energy
    3. Heat energy
    4. Radiation energy
  3. True or False: Energy is able to remain in one form that is usable over and over again.
    1. True
    2. False

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Roller Coasters

Saturday November 7, 2009

We're going to build monster roller coasters in your house using just a couple of simple materials. You might have heard how energy cannot be created or destroyed, but it can be transferred or transformed (if you haven't that's okay - you'll pick it up while doing this activity).

Roller coasters are a prime example of energy transfer: You start at the top of a big hill at low speeds (high gravitational potential energy), then race down a slope at break-neck speed (potential transforming into kinetic) until you bottom out and enter a loop (highest kinetic energy, lowest potential energy). At the top of the loop, your speed slows (increasing your potential energy), but then you speed up again and you zoom near the bottom exit of the loop (increasing your kinetic energy), and you're off again!

Here's what you need:

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  • marbles
  • masking tape
  • 3/4" pipe foam insulation (NOT neoprene and NOT the kind with built-in adhesive tape)

To make the roller coasters, you'll need foam pipe insulation, which is sold by the six-foot increments at the hardware store. You'll be slicing them in half lengthwise, so each piece makes twelve feet of track. It comes in all sizes, so bring your marbles when you select the size. The ¾” size fits most marbles, but if you’re using ball bearings or shooter marbles, try those out at the store. (At the very least you’ll get smiles and interest from the hardware store sales people.) Cut most of the track lengthwise (the hard way) with scissors. You’ll find it is already sliced on one side, so this makes your task easier. Leave a few pieces uncut to become “tunnels” for later roller coasters.

Read for some 'vintage Aurora' video? This is one of the very first videos ever made by Supercharged Science:

Download Student Worksheet & Exercises

Tips & Tricks

Loops Swing the track around in a complete circle and attach the outside of the track to chairs, table legs, and hard floors with tape to secure in place. Loops take a bit of speed to make it through, so have your partner hold it while you test it out before taping. Start with smaller loops and increase in size to match your entrance velocity into the loop. Loops can be used to slow a marble down if speed is a problem.

Camel-Backs Make a hill out of track in an upside-down U-shape. Good for show, especially if you get the hill height just right so the marble comes off the track slightly, then back on without missing a beat.

Whirly-Birds Take a loop and make it horizontal. Great around poles and posts, but just keep the bank angle steep enough and the marble speed fast enough so it doesn’t fly off track.

Corkscrew Start with a basic loop, then spread apart the entrance and exit points. The further apart they get, the more fun it becomes. Corkscrews usually require more speed than loops of the same size.

Jump Track A major show-off feature that requires very rigid entrance and exit points on the track. Use a lot of tape and incline the entrance (end of the track) slightly while declining the exit (beginning of new track piece).

Pretzel The cream of the crop in maneuvers. Make a very loose knot that resembles a pretzel. Bank angles and speed are the most critical, with rigid track positioning a close second. If you’re having trouble, make the pretzel smaller and try again. You can bank the track at any angle because the foam is so soft. Use lots of tape and a firm surface (bookcases, chairs, etc).

Troubleshooting Marbles will fly everywhere, so make sure you have a lot of extras! If your marble is not following your track, look very carefully for the point of departure – where it flies off.

-Does the track change position with the weight of the marble, making it fly off course? Make the track more rigid by taping it to a surface.
-Is the marble jumping over the track wall? Increase your bank angle (the amount of twist the track makes along its length).
-Does your marble just fall out of the loop? Increase your marble speed by starting at a higher position. When all else fails and your marble still won’t stay on the track, make it a tunnel section by taping another piece on top the main track. Spiral-wrap the tape along the length of both pieces to secure them together.

HOT TIPS for ULTRA-COOL PARENTS: This lab is an excellent opportunity for kids to practice their resilience, because we guarantee this experiment will not work the first several times they try it. While you can certainly help the kids out, it’s important that you help them figure it out on their own. You can do this by asking questions instead of rushing in to solve their problems. For instance, when the marble flies off the track, you can step back and say:

“Hmmm… did the marble go to fast or too slow?”

“Where did it fly off?”

“Wow – I’ll bet you didn’t expect that to happen. Now what are you going to try?”

Become their biggest fan by cheering them on, encouraging them to make mistakes, and try something new (even if they aren’t sure if it will work out).

Check out this cool roller coaster from one of our students!

Exercises 

  1. What type of energy does a marble have while flying down the track of a roller coaster?
  2. What type of energy does the marble have when you are holding it at the top of the track?
  3. At the top of a camel back hill, which is higher for the marble, kinetic or potential energy?
  4. At the top of an inverted loop, which energy is higher, kinetic or potential energy?

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Mystery Toy

Saturday November 7, 2009

Note: Do the pendulum experiment first, and when you’re done with the heavy nut from that activity, just use it in this experiment.


You can easily create one of these mystery toys out of an old baking powder can, a heavy rock, two paper clips, and a rubber band (at least 3″ x 1/4″).  It will keep small kids and cats busy for hours.


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Here’s what you get:


  • can with a lid
  • heavy rock or large nut
  • two paper clips
  • rubber band

You’ll need two holds punched through your container  – one in the lid and the bottom. Thread your rubber band through the heavy washer and tie it off (this is important!).  Poke the ends of the rubber band through one of the holes and catch it on the other side with a paper clip.  (Just push a paper clip partway through so the rubber band doesn’t slip back through the hole.)  Do this for both sides, and make sure that your rubber band is a pulled mildly-tight inside the can.  You want the hexnut to dangle in the center of the can without touching the sides of the container.



 
Download Student Worksheet & Exercises


Now for the fun part… gently roll the can on a smooth floor away from you.  The can should roll, slow down, stop, and return to  you!  If it doesn’t, check the rubber band tightness inside the can.


The hexnut is a weight that twists up the rubber band as the can rolls around it.  The kinetic energy (the rolling motion of the can) transforms into potential (elastic) energy stored in the rubber band the free side twists around. The can stops (this is the point of highest potential energy) and returns to you (potential energy is being transformed into kinetic). The farther the toy is rolled the more elastic potential energy it stores.


Exercises


  1. Explain in your own words two types of energy transfer:
  2. True or false: All energy in a system is lost to heat.
    1. True
    2. False

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Unit 5: Energy (Kinetic) Video

Saturday November 7, 2009

This lesson we’re going to talk about kinetic energy, transfer of energy, conservation of energy and energy efficiency. This video gets you started on the right foot. We’ll outline what’s coming up for this week and how to get the most out of our lesson together. Enjoy!



Unit 5: Energy (Potential) Video

Saturday November 7, 2009

This lesson we’re going to talk about the two main categories of energy: potential and kinetic. We will talk about transfer of energy and we will also discuss conservation of energy and energy efficiency. This video gets you started on the right foot. We’ll outline what’s coming up for this week and how to get the most out of our lesson together. Enjoy!



Whackapow!

Saturday November 7, 2009

In this experiment, you’re looking for two different things:  first you’ll be dropping objects and making craters in a bowl of flour to see how energy is transformed from potential to kinetic, but you’ll also note that no matter how carefully you do the experiment, you’ll never get the same exact impact location twice.


To get started, you’ll need to gather your materials for this experiment. Here’s what you need:


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  • several balls of different weights no bigger then the size of a baseball (golf ball, racket ball, ping pong ball, marble etc. are good choices)
  • fill a good size container or mixing bowl with flour or corn starch (or any kind of light powder)
  • If you’re measuring your results, you’ll also need a tape measure (or yard stick) and a spring scale (or kitchen scale).

Are you ready?


1. Fill the container about 2 inches or so deep with the flour.


2. Weigh one of the balls (If you can, weigh it in grams).


3. Hold the ball about 3 feet (one meter) above the container with the flour.


4. Drop the ball.


5. Whackapow! Now take a look at how deep the ball went and how far the flour spread. (If all your balls are the same size but different weights it’s worth it to measure the size of the splash and the depth the ball went. If they are not, don’t worry about it. The different sizes will effect the splash and depth erratically.


6. Try it with different balls. Be sure to record the mass of each ball and calculate the potential energy for each ball.



Each one of the balls you dropped had a certain amount of potential energy that depended on the mass of the ball and the height it was dropped from. As the ball dropped the potential energy changed to kinetic energy until, “whackapow”, the kinetic energy of the ball collided with and scattered the flour. The kinetic energy of the ball transferred kinetic energy and heat energy to the flour.


For Advanced Students:

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Calculate the gravitational potential energy of the ball. Take the mass of the ball, multiply it by 10 m/s2 and multiply that by 1 meter. For example, if your ball had a mass of 70 grams (you need to convert that to kilograms so divide it by 1000 so that would be .07 grams) your calculation would be


PE=.07 x 10 x 1 = .7 Joules of potential energy.


So, how much kinetic energy did the ball in the example have the moment it impacted the flour? Well, if all the potential energy of the ball transfers to kinetic energy, the ball has .7 Joules of kinetic energy.


Create a table in your science journal or use ours. (You’ll need Microsoft Excel to use this file.)


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Ball Bounce

Saturday November 7, 2009

When you toss down a ball, gravity pulls on the ball as it falls (creating kinetic energy) until it smacks the pavement, converting it back to potential energy as it bounces up again. This cycles between kinetic and potential energy as long as the ball continues to bounce.


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But note that when you drop the ball, it doesn’t rise up to the same height again. If the ball did return to the same height, this means you recovered all the kinetic energy into potential energy and you have a 100% efficient machine at work. But that’s not what happens, is it? Where did the rest of the energy go? Some of the energy was lost as heat and sound. (Did you hear something when the ball hit the floor?)



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Elastic Potential Energy

Saturday November 7, 2009

There are many different kinds of potential energy.  We’ve already worked with gravitational potential energy, so let’s take a look at elastic potential energy.


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Materials: a rubber band


A simple way to demonstrate elastic energy is to stretch a rubber band without releasing it.  The stretch in the rubber band is your potential energy. When you let go of the rubber band, you are releasing the potential energy, and when you aim it toward a wall, it’s converted into motion (kinetic energy).



Here’s another fun example:  the rubber band can also show how every is converted from one form to another.  If you place the rubber band against a part of you that is sensitive to temperature changes (like a cheek or upper lip), you can sense when the band heats up.  Simply stretch and release the rubber band over and over, testing the temperature as you go. Does it feel warmer in certain spots, or in just one location?


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Go Go GO!!

Saturday November 7, 2009

This is a nit-picky experiment that focuses on the energy transfer of rolling cars.  You’ll be placing objects and moving them about to gather information about the potential and kinetic energy.


We’ll also be taking data and recording the results as well as doing a few math calculations, so if math isn’t your thing, feel free to skip it.


Here’s what you need:


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  • a few toy cars (or anything that rolls like a skate)
  • a board, book or car track
  • measuring tape

The setup is simple.  Here’s what you do:


1. Set up the track (board or book so that there’s a nice slant to the floor).


2. Put a car on the track.


3. Let the car go.


4. Mark or measure how far it went.



Download Student Worksheet & Exercises


As you lifted the car onto the track you gave the car potential energy. As the car went down the track and reached the floor the car lost potential energy and gained kinetic energy. When the car hit the floor it no longer had any potential energy only kinetic.


If the car was 100% energy efficient, the car would keep going forever. It would never have any energy transferred to useless energy. Your cars didn’t go forever did they? Nope, they stopped and some stopped before others. The ones that went farther were more energy efficient. Less of their energy was transferred to useless energy than the cars that went less far.


Where did the energy go? To heat energy, created by the friction of the wheels, and to sound energy. Was energy lost? NOOOO, it was only changed. If you could capture the heat energy and the sound energy and add it to the the kinetic energy, the sum would be equal to the original amount of energy the car had when it was sitting on top of the ramp.


For K-8 grades, click here to download a data sheet.


For Advanced Students, click  here for the data log sheet. You’ll need Microsoft Excel to use this file.


Exercises


  1. Where is the potential energy greatest?
  2. Where is the kinetic energy greatest?
  3. Where is potential energy lowest?
  4. Where is kinetic energy lowest?
  5. Where is KE increasing, and PE is decreasing?
  6. Where is PE increasing and KE decreasing?

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Pendulums

Saturday November 7, 2009

This is a very simple yet powerful demonstration that shows how potential energy and kinetic energy transfer from one to the other and back again, over and over.  Once you wrap your head around this concept, you'll be well on your way to designing world-class roller coasters.

For these experiments, find your materials:

  • some string
  • a bit of tape
  • a washer or a weight of some kind
  • set of magnets (at least 6, but more is better)

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Here's what you do:

1. Make the string into a 2 foot or so length.

2. Tie the string to the washer, or weight.

3. Tape the other end of the string to a table.

4. Lift the weight and let go, causing the weight to swing back and forth at the end of the pendulum.

Download Student Worksheet & Exercises

Watch the pendulum for a bit and describe what it’s doing as far as energy goes. Some questions to think about include:

  • Where is the potential energy greatest?
  • Where is the kinetic energy greatest?
  • Where is potential energy lowest?
  • Where is kinetic energy lowest?
  • Where is KE increasing, and PE is decreasing?
  • Where is PE increasing and KE decreasing?
  • Where did the energy come from in the first place?

Remember, potential energy is highest where the weight is the highest.

Kinetic energy is highest were the weight is moving the fastest. So potential energy is highest at the ends of the swings. Here’s a coincidence, that’s also where kinetic energy is the lowest since the weight is moving the least.

Where’s potential energy the lowest? At the middle or lowest part of the swing. Another coincidence, this is where kinetic energy is the highest! Now, wait a minute...coincidence or physics? It’s physics right?

In fact, it’s conservation of energy. No energy is created or destroyed, so as PE gets lower KE must get higher. As KE gets higher PE must get lower. It’s the law...the law of conservation of energy! Lastly, where did the energy come from in the first place? It came from you. You added energy (increased PE) when you lifted the weight.

(By the way, you did work on the weight by lifting it the distance you lifted it. You put a certain amount of Joules of energy into the pendulum system. Where did you get that energy? From your morning Wheaties!)

Chaos Pendulum

For this next experiment, we'll be using magnets to add energy into the system by having a magnetic pendulum interact with magnets carefully spaced around the pendulum. Watch the video to learn how to set this one up.  You'll need a set of magnets (at least one of them is a ring magnet so you can easily thread a string through it), tape, string, and a table or chair. Are you ready?

Exercises

  1. Why can we never make a machine that powers itself over and over again?
    1. Energy is mostly lost to heat.
    2. Energy is completely used up.
    3. Energy is unlimited, but is absorbed by neighboring air molecules.
    4. None of these
  2. In the pendulum, as kinetic energy increases, potential energy ______________.
    1. Increases
    2. Decreases
  3. As potential energy decreases, kinetic energy _________________.
    1. Increases
    2. Decreases

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Universal Troubleshooting Process (UTP): Going Beyond the Scientific Method

Sunday October 25, 2009

Have you ever torn apart something and then couldn’t figure out how to get it back together again so that it worked? Worse, you knew that if you had only taken a few moments to think about the problem or jot something down, you know it would have taken you far less time to figure it out?


If you’ve used the Scientific Method, you know how cumbersome it can be at times, and to be completely honest, it really isn’t the right tool for every problem in science. While I’ve mentioned the UTP before, I haven’t actually given you the exact steps to follow… until now.


Here’s a great way to explain how this works: first, you need the right starting position. Imagine if I pulled a single card out of a deck of playing cards and asked you to guess what it is. At first, you might start by randomly guessing any card that comes to your ind, but after while, you forget which you have already guessed and which you can’t tried yet. Sound frustrating? It is. Sound inefficient? It is. This is what it’s like to do a science experiment without tracking your progress. It’s insane, and yet people do it all the time. No wonder they find science frustrating!


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Back to guessing the right card: What if you are more clever about the question you ask? For example:


Q. Is the card a red suit or a black suit? A. red.


Q. Is it a heart or a diamond? A. diamond


Q. Is it a face card or a number card? A. number


Q. Is the number 5 or below (the ace is the number 1)? A. no


Q. Is the number odd or even? A. Odd


Now after asking only five questions, you know that there are only two possibilities: the 7 or 9 of diamonds.So you ask your last question:


Q. Is it the 9 of diamonds? A. no


Solution: It is the 7 of diamonds.


The point is that in order to be  great scientist, you need to be able to ask the right questions. This will save you hours of frustration whether you’re tearing apart the toaster, fixing the DVD player, or trying to fix the car. Each question you ask should lead you closer to the problem area by eliminating possibilities as you go along.


The key is knowing your equipment. If you didn’t know what a deck of cards were, then it wouldn’t be fair to ask you to guess one of the cards. This means if you are trying to solve a problem, you must mentally prepare ahead of time – something this looks like reading a book about plumbing, talking with the hardware store gurus, or doing background research before tackling the dishwasher.


So get your feet wet and stick your your nose into technical publications and always keep your ears open to the voice of experience. It has and always will be the greatest teacher.


The 10 Steps to Fix Anything

How to Use the Universal Throubleshooting Process (UTP)

  1. Positive Attitude
  2. Write Down The Symptoms
  3. Make A Damage Control Plan
  4. Reproduce The Problem
  5. Do appropriate General Maintenance
  6. Find The Cause
  7. Fix it
  8. Test
  9. Celebrate!
  10. Prevent Future Occurrences

How Do I Use the UTP?

Here’s an example of how to use it to fix electronics and computer issues, but you can really use it to fix anything you want. Here are the steps broken down in detail:


 UTP Step 1 – Positive Attitude

  1. Don’t panic
  2. Don’t get mad
  3. Problems are not personal
  4. Remember, with the right information and process, you can fix this.

 UTP Step 2 –  Write Down The Symptoms

  1. Date
  2. Model Name and Number
  3. How old is it?
  4. What is it’s configuration (options, modifications, etc.)
  5. What peripherals are connected to it?
  6. What Operating system is it using?
  7. What are the symptoms of the problem?  (Are you sure this is really a problem?)
    • Ex. I can’t access my email
    • Ex. The battery only lasts for 5 minutes then gives a warning
  8. Write down any error messages and describe any other symptoms.
    • Ex. “Unable to complete installation.  Error #4033”
    • Ex. Battery LED flashes yellow
  9. Is the problem Intermittent or Reproducible?
  10. If Reproducible: what steps did you take to produce the problem? How can you make the symptoms go away (if at all)?
  11. If Intermittent: How often does it seem to happen? What seems to make it more frequent? What seems to make it less frequent? What seems to make it go away?
  12. Are there any other symptoms or changes that you noticed occurred around the same time the problem arose?
  13. Are there any other components or software that might be involved?
  14. When did the problem first appear?
  15. What else happened around that time? New software installed? New hardware installed? System maintenance done? Software downloaded? System configuration changes?
  16. Does the problem occur with all users, or only certain ones?
  17. Does the problem only occur in certain locations?
  18. Does the problem occur immediately on start-up, or does it take a while?

UTP Step 3 – Make A Damage Control Plan

Take steps to make sure things don’t get worse either because the problem persists, or even because of troubleshooting efforts


  1. Is there any danger for physical safety?
  2. How can I limit potential damage to equipment?
    • Backup critical data, including configuration data (everything if possible)
    • Backup, Norton Ghost
    • Disconnect from other unrelated equipment

UTP Step 4 – Reproduce The Problem

  1. Do whatever you wrote down in Step 2 to make the problem re-occur.
  2. If you can’t reproduce it, you often can’t fix it.

UTP Step 5 – Do appropriate General Maintenance

  1. If it’s difficult/risky and unlikely to be the cause, skip it for now.
  2. Scan for viruses
  3. Install Windows updates
  4. Install other software updates (as appropriate)
  5. Disk Error Checking (Scandisk)
  6. Defrag

UTP Step 6 – Find The Cause

  1. Read the manual, FAQ and Help.
  2. Search online for answers.
  3. Call tech support if it’s free and competent.
  4. Is this a known problem? If so, follow the recommended procedures.  Hint: Make sure your symptoms really match and the solution seems reasonable. (i.e. if the solution is to re-format your hard drive and re-install Windows, consider other options first)
  5. Eliminate groups of possibilities in chunks
    • See if a peripheral works with another computer (Ex. A printer)
    • Ex See if it works in Safe Mode. (<F8> repeatedly on startup)
    • Ex Use “msconfig” to eliminate startup programs in groups
    • Ex Use System Restore
    • Re-install Troublesome software

UTP Step 7 – Fix it

  1. If you have instructions, FOLLOW THEM!
  2. Repair or replace the defective component
  3. Perform configuration changes required to fix problem
  4. Remove or re-install problematic software
  5. Develop a work-around
  6. etc.

UTP Step 8 – Test

Never forget to thoroughly test, especially if it’s for someone else.


  1. Did the symptom go away?
  2. Did I create any other problems?
  3. Let the User test, if appropriate

UTP Step 9 – Celebrate

Take pride in your work.  Celebrate your accomplishment! Go out for a soda, brag about it, whatever your thing is.


UTP Step 10 – Prevent Future Occurrences

  1. Be sure you understand how to keep it from happening again
  2. If there are other users, let them know
  3. Print up instructions, if required.

[/am4show]


Exercises for Levers & Simple Machines

Saturday October 17, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
[am4show have=’p8;p9;p14;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


Energy Exercises

1. Everything in the universe can be categorized as what two things?


2. What is energy?


3. What is work?


4. If someone carries a lawn chair to their roof to watch the meteor showers, is work done on the chair?


5. What if the chair falls off the roof? Is work done on the chair then?


6. If someone pushes a train with all their might, but the train doesn’t move, is work done?


7. What are two units used to measure work?


8. What is power?


9. What are two units to measure power?


10. Where does all the energy you get from food originate from?


Simple Machines/Levers Exercises

1. Can you name the six simple machines?


2. It is easier to move things using a lever but what has to happen to lessen the force needed to move the load?


3. Describe a first-class lever. Can you give an example?


4. Describe a second-class lever. Can you give an example?


5. Describe a third-class lever. Can you give an example?


For Advanced Students, we have more advanced energy questions in addition:


[/am4show][am4show have=’p9;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


Energy Calculations

Work = Force x Distance
Power = Work / Time


1. A mouse that weighs 4 ounces, jumps, step by step, up a 2 meter tall flight of stairs. What kind of work did that little guy do? (1 newton is 4 ounces)


2. If it took him 3 minutes (180 seconds) to do it, what power did he exert?


3. Bob’s car breaks down. He needs to push on the car with a force of 1000 Newtons to get the car to go 30 meters (about 100 feet). How much work does he do?


4. If Bob takes 5 seconds to do it, how much power does he use?


5. Just for fun, let’s convert that to horsepower. 1 Watt = .001 horsepower


[/am4show] Need answers?


Exercises for Pulleys

Saturday October 17, 2009

Let’s see how much you’ve picked up with these experiments and the reading – answer as best as you can. (No peeking at the answers until you’re done!) Just relax and see what jumps to mind when you read the question. You can also print these out and jot down your answers in your science notebook.
[am4show have=’p8;p9;p14;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


1. If I’m talking about simple machines, what does load mean?


2. So what does effort mean when it comes to simple machines?


3. With the pulleys, as your effort got less and less, what happened to the amount of string you had to pull?


4. What is mechanical advantage?


For Advanced Students:

Warning: the following questions are “mathy”. Don’t worry about these if it gets in the way of your enjoyment or understanding of the lesson.


[/am4show][am4show have=’p9;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


5. If a lever had a mechanical advantage of 10 and you wanted to lift a 50 pound watermelon, how many pounds of force would you have to use for the effort?


6. If a pulley had a mechanical advantage of 500 and you wanted to lift a 2000 pound hippo, how many pounds of force would you have to use for the effort?


7. Same hippo different units. Newtons are the official unit of force. So to do this officially, a 2000 pound hippo would take about 9000 Newtons to lift. If you lift that hippo 2 meters, how much work did you do? Remember, work is force x distance.


8. One last question. This one’s a little tricky. So if you lifted the hippo 2 meters, how much chain (because string’s not going to cut it) did you pull?


[/am4show] Need answers?


Answers for Levers & Simple Machines Exercises

Saturday October 17, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for K-8 and here for K-12.


[am4show have=’p8;p9;p14;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


Answers to Energy Exercises:

1. Matter and energy.
2. The ability of an object or system to do work on another object or system. Energy is defined in the physics books as the ability to do work.
3. Work is moving an object against a force over a distance. Work = force x distance
4. Yes. The chair has been moved a distance, against the force of gravity.
5. Nope, the chair moves a distance, but it moves with the force of gravity. Work is moving something a distance against a force. In this case, the chair does not move against a force. No work is done.
6. Nope again! There’s no distance moved so…no work done.
7. Joules and calories.
8. The amount of work done in a given amount of time. Power = work divided by time.
9. Watts and horsepower.
10. The sun. You are powered by the sun!


Answers to Simple Machines/Levers Exercises

1. The six machines are the inclined plane, the wheel and axle, the lever, the pulley, the wedge, and the screw.
2. The distance that the effort moves is much greater than the distance the load moves.
3. A first-class lever is a lever in which the fulcrum is located in between the effort and the load. Some examples are see-saw, a hammer (when it’s used to pull nails), scissors, and pliers.
4. In a second-class lever, the load is between the fulcrum and the effort. Some examples are a wheel-barrow, a door, a stapler, and a nut-cracker.
5. The third-class lever has the effort between the load and the fulcrum. A few examples of this are tweezers, fishing rods, your jaw, and your arm


For Advanced Students:

[/am4show][am4show have=’p9;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


Answers to Energy Calculations

1. work = force x distance so
work = 1 newton x 2 meters
work = 2 Joules


2. Power = work/time
power = 2/180
power = .01 Watts


3. work = force x distance
work = 1000 x 30
work = 30,000 Joules (go Bob!)


4. power = work x time
power = 30,000/5
power = 6000 Watts (Wow! Big Bob!)


5. 6000 Watts x .001 = 6 horsepower (No Viper, but pretty impressive!)


[/am4show]


Answers for Pulleys Exercises

Saturday October 17, 2009

Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!


Here’s printer-friendly versions of the exercises and answers for you to print out: Simply click here for K-8 and here for K-12.


Answers:
[am4show have=’p8;p9;p14;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]
1. The load is what you are lifting or moving.
2. Effort is the force needed to lift the load.
3. As the effort got less, the amount of string (distance) got greater and greater.
4. Mechanical advantage is the factor by which a mechanism multiplies the force put into it.


[/am4show][am4show have=’p9;p41;’ guest_error=’Guest error message’ user_error=’User error message’ ]


For Advanced Students:

5. 5 pounds. The lever has a mechanical advantage of 10 so it multiplies the force by 10. So 5 x 10 = 50. (By the way, when you cut up that watermelon invite me over!)
6. 4 pounds. 4 x 500 = 2000
7. 18,000 Joules of work. 9000 Newtons x 2 meters = 18,000 Joules.
8. 1000 meters (3280 ft) of chain!!!


[/am4show]


Homemade Pulleys

Saturday October 17, 2009
These homemade pulleys work great as long as they glide freely over the coat hanger wire (meaning that if you give them a spin, they keep spinning for a few more seconds).  You can adjust the amount of friction in the pulley by adjusting the where the metal wire bends after it emerges from the pulley.

[am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ] All you need is a wire coathanger, a thread spool, and a pair of vice grips... and the video below.


Download Student Worksheet

Cut a wire coat-hanger at the lower points (at the base of the triangular shape) and use the hook section to make your pulley. Thread both straight ends through a thread spool, crossing in the middle, and bend wire downwards to secure spool in place. Be sure the spool turns freely. Use hook for easy attachment. (These pulleys work well for the return-pulley system experiment in this section.)
If you still have trouble, you can purchase pulleys from the hardware store, or more inexpensively, from a farm supply store. (We get ours from the chicken coup section – no kidding!) If you really want to go hog-wild with pulleys, get a bunch and clip them onto climbing-rated carabineer. [/am4show]

Return-Mechanism Pulley System

Saturday October 17, 2009
Silly as our application for this experiment may sound, we use this system to keep pens handy near the shopping list on the fridge.  It’s saved us from many pen-searches over the years!

We install these at various places around the house (by the telephone, fridge, front door, anywhere that you usually need a pen at the last minute), and have even seen them at the counters of local video-rental stores.

[am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ]

Download Student Worksheet

Troubleshooting: It’s important to note that the weight needs to slide freely both up and down the length of the cord (which is why fishing line is a great choice – the surface of the line is very low friction). Another important tip: the weights you use must weigh more than the object at the end of the string plus the force of friction in the lines (and the pulley).  Hollow, metal objects work great like nuts (for bolts).

You’ll need to practice to find just the right balance point: where the pen flies up to its resting position when you let go of the pen.

This is a great addition to any tree house or playground structure!  Hang a loop of rope from a tree branch (don't forget to thread the pulleys onto the rope before you tie the knot!  Connect one pulley to the basket handle made from a circle of short rope.  Tie a length of rope to the basket handle, then up through one tree pulley, down through the basket pulley, and up through the second tree pulley. Thread a 6" length of PVC pipe onto the end and tie the rope back onto itself to form a handle.

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Block & Tackle

Saturday October 17, 2009
Simple machines make our lives easier. They make it easier to lift, move and build things. Chances are that you use simple machines more than you think. If you have ever screwed in a light bulb, put the lid on a jam jar, put keys on a keychain, pierced food with a fork, walked up a ramp, or propped open a door, you've made good use of simple machines. A block and tackle setup is also a simple machine.

Block and tackle refers to pulleys and rope (in that order). One kid can drag ten adults across the room with this simple setup – we've done this class lots of times with kids and parents, and it really works! Be careful with this experiment - you'll want to keep your fingers away from the rope and don't pull too hard (kids really get carried away with this one!)

If you haven't already, make sure you try out the broomstick version of this activity first.

[am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ] Materials:
  • Rope
  • pulleys
  • chain link fence (or a broom)
  • three people
Cut off about 12" of rope and circle a loop around a strong support, like a chain link fence. Before you tie a knot, thread three pulleys onto the rope… and now tie it off.

Make another circle of rope and add three more pulleys onto it. Loop the rope over the handle of a mop or broom. Thread the rest of the nylon rope through zigzag fashion first through one pulley on the fence, then through a pulley on the mop, then to an open pulley back on the fence, then another free pulley on the mop, etc… Knot the end of the rope to the mop. You should have one free end of rope left.

Attach a kid to the free end of the rope by adding a handle.  You can thread a rope through a 6" piece of PVC pipe and tie the rope back on itself.  Attach adults to the mop, holding it straight out in front of their chest.  The adults' job is to resist the pull they will feel as the kid pulls with his end of the rope.


Download Student Worksheet [/am4show]

Pull Two Friends with One Hand

Saturday October 17, 2009
We're going to be using pulleys to pull two (or more) kids with one hand. You will be using something called ‘Mechanical Advantage’, which is like using your brains instead of brute strength. When you thread the rope around the broom handles, you use 'mechanical advantage' to leverage your strength and pull more than you normally could handle.

How can you possibly pull with more strength than you have? Easy - you trade ‘force’ for ‘distance’ - you can pull ten people with one hand, but you have to pull ten feet of rope for every one foot they travel.

Here's what you do: [am4show have='p8;p9;p14;p41;p88;p92;' guest_error='Guest error message' user_error='User error message' ]
  • nylon rope (at least 50')
  • two strong dowels (like the handle from a broomstick)
  • friends and you

Download Student Worksheet

Have two people face each other and each hold a smooth pipe or strong dowel (like a mop or broom) horizontally straight out in front of their chest.   Tie a length of strong nylon rope (slippery rope works best to minimize friction) near the end of the mop.

Drape the rope over the second handle (broom), loop around the bottom, then back to the top of the broom.  You're going to zigzag the rope back and forth between the mop and broom until you have four strings on each handle.

Attach a third person to the free end of the rope.  Make a quick handle for a third person: Thread a 6" length of PVC pipe onto the end and tie the rope back onto itself to form a handle.

The two people hold the dowels will not be able to resist the pull you give when pulling on the end of the rope! Be careful with this one - there's a lot of force going through your rope, and that's usually the first thing to break. If everyone pulls gently, you don't have to worry.

Troubleshooting Tip: If you’re finding there’s just too much friction between the rope and the broomstick (meaning that the rope doesn’t slide smoothly over the broom handles, then click here to learn how to upgrade to pulleys. [/am4show]

Simple Pulley Experiments

Saturday October 17, 2009
Are you curious about pulleys? This set of experiments will give you a good taste of what pulleys are, how to thread them up, and how you can use them to lift heavy things.

We'll also learn how to take data with our setup and set the stage for doing the ultra-cool Pulley Lift experiments.

Are you ready? [am4show have='p8;p9;p14;p41;p75;p85;p88;p92;' guest_error='Guest error message' user_error='User error message' ] For this experiment, you will need:

  • One pulley (from the hardware store... get small ones that spin as freely as possible. You’ll need three single pulleys or if you can find one get a double pulley to make our later experiment easier.)
  • About four feet of string
  • 2 paper cups
  • many little masses (about 50 marbles, pennies, washers etc.)
  • Yardstick or measuring tape
  • A scale (optional)
  • 2 paper clips
  • Nail or some sort of sharp pokey thing
  • Table
Download Student Worksheet & Exercises

“Advanced students: Download your Simple Pulley Experiments

1. Take a look at the video to see how to make your “mass carriers”. Use the nail to poke a hole in both sides of the cup. Be careful to poke the cup...not your finger! Thread about 4 inches of string or a pipe cleaner through both holes. Make sure the string is a little loose. Make two of these mass carriers. One is going to be your load (what you lift) and the other is going to be your effort (the force that does the lifting).

2. Dangle the pulley from the table (check out the picture).

3. Bend your two paper clips into hooks.

4. Take about three feet of string and tie your paper clip hooks to both ends.

5. Thread your string through the pulley and let the ends dangle.

6. Put 40 masses (coins or whatever you’re using) into one of the mass carriers. Attach it to one of the strings and put it on the floor. This is your load.

7. Attach the other mass carrier to the other end of the string (which should be dangling a foot or less from the pulley). This is your effort.

8. Drop masses into the effort cup. Continue dropping until the effort can lift the load.

9. Once your effort lifts the load, you can collect some data. First allow the effort to lift the load about one foot (30 cm) into the air. This is best done if you manually pull the effort until the load is one foot off the ground. Measure how far the effort has to move to lift the load one foot.

10. When you have that measurement, you can either count the number of masses in the load and the effort cup or if you have a scale, you can get the mass of the load and the effort.

11. Write your data into your pulley data table in your science journal.

Double Pulley Experiment

You need:

Same stuff you needed in Experiment 1, except that now you need two pulleys.


1. Attach the string to the hook that’s on the bottom of your top pulley.

2. Thread the string through the bottom pulley.

3. Thread the string up and through the top pulley.

4. Attach the string to the effort.

5. Attach the load to the bottom pulley.

6. Once you get it all together, do the same thing as before. Put 40 masses in the load and put masses in the effort until it can lift the load.

7. When you get the load to lift, collect the data. How far does the effort have to move now in order to lift the load one foot (30 cm)? How many masses (or how much mass, if you have a scale) did it take to lift the load?

8. Enter your data into your pulley table in your science journal.

Triple Pulley Experimentitem7

You Need

Same stuff as before If you have a double pulley or three pulleys you can give this a shot. If not, don’t worry about this experiment.

Do the same thing you did in experiments 1 and 2 but just use 3 pulleys. It’s pretty tricky to rig up 3 pulleys so look carefully at the pictures. The top pulley in the picture is a double pulley.

1. Attach the string to the bottom pulley. The bottom pulley is the single pulley.item8
2. Thread the string up and through one of the pulleys in the top pulley. The top pulley is the double pulley.

3. Take the string and thread it through the bottom pulley.

4. Now keep going around and thread it again through the other pulley in the top (double) pulley.

5. Almost there. Attach the load to the bottom pulley.

6. Last, attach the effort to the string.

7. Phew, that’s it. Now play with it!

Take a look at the table and compare your data. If you have decent pulleys, you should get some nice results. For one pulley, you should have found that the amount of mass it takes to lift the load is about the same as the amount of mass of the load. Also, the distance the load moves is about the same as the distance the effort moves.

All you’re really doing with one pulley, is changing the direction of the force. The effort force is down but the load moves up.

Now, however, take a look at two pulleys. The mass needed to lift the load is now about half the force of the load itself! The distance changed too. Now the distance you needed to move the effort, is about twice the distance that the load moves. When you do a little math, you notice that, as always, work in equals work out (it won’t be exactly but it should be pretty close if your pulleys have low friction).

What happened with three pulleys? You needed about 1/3 the mass and 3 times the distance right? With a long enough rope, and enough pulleys you can lift anything! Just like with the lever, the pulley, like all simple machines, does a force and distance switcheroo.

The more distance the string has to move through the pulleys, the less force is needed to lift the object. The work in, is equal to the work out (allowing for loss of work due to friction) but the force needed is much less.

Exercises Answer the questions below:
  1. What is the load and effort of a pulley? Draw a pulley and label it.
  2. What is the best way to say what a simple machine helps us do?
    1. Do work without changing force applied
    2. Change the direction or strength of a force
    3. Lift heavy shipping containers
    4. None of these
  3.  Name one other type simple machine and an example:
[/am4show]

Inclined Plane

Saturday October 17, 2009

What’s an inclined plane? Jar lids, spiral staircases, light bulbs, and key rings. These are all examples of inclined planes that wind around themselves.  Some inclined planes are used to lower and raise things (like a jack or ramp), but they can also used to hold objects together (like jar lids or light bulb threads).


Here’s a quick experiment you can do to show yourself how something straight, like a ramp, is really the same as a spiral staircase.


[am4show have=’p8;p9;p14;p41;p151;p75;p85;p88;p92;’ guest_error=’Guest error message’ user_error=’User error message’ ]


Here’s what you need to find:


  • sheet of paper
  • short dowel or cardboard tube from a coat hanger
  • tape
  • ruler

Find a short dowel or use a cardboard tube from a coat-hanger.  Roll a sheet of paper around the tube beginning at the short side and roll toward the triangle point, keeping the base even as it rolls (in the video, I just rolled it, so only use the dowel if you have trouble keeping it rolled evenly.)


Notice that the inclined plane (hypotenuse) spirals up as a tread as you roll. Remind you of screw threads?  Those are inclined planes. If you have trouble figuring out how to do this experiment, just watch the video clip below:



Download Student Worksheet & Exercises


Inclined planes are simple machines. It’s how people used to lift heavy things (like the top stones for a pyramid).


Here’s another twist on the inclined plane: a wedge is a double inclined plane (top and bottom surfaces are inclined planes). You have lots of wedges at home: forks, knives, and nails just name a few.


When you stick a fork in food, it splits the food apart. You can make a simple wedge from a block of wood and drive it under a heavy block (like a tree stump or large book) with a kid on top.


Exercises


  1. What is one way to describe energy?
    1. The amount of atoms moving around at any given moment
    2. Electrons flowing from one area to another
    3. The ability to do work
    4. The square root of the speed of an electron
  2. Work is when something moves when:
    1. Force is applied
    2. Energy is used
    3. Electrons are lost or gained
    4. A group of atoms vibrate
  3. Name two simple machines:
  4. Name one example of a simple machine:

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First, Second, and Third Class Levers

Saturday October 17, 2009

Parts of the Lever

Levers, being simple machines, have only three simple parts. The load, the effort, and the fulcrum. Let’s start with the load. The load is basically what it is you’re trying to lift. The books in the last experiment where the load. Now for the effort. That’s you. In the last experiment, you were putting the force on the lever to lift the load. You were the effort. The effort is any kind of force used to lift the load. Last for the fulcrum. It is the pivot that the lever turns on. The fulcrum, as we’ll play with a bit more later, is the key to the effectiveness of the lever.


There are three types of levers. Their names are first-class, second-class and third-class. I love it when it’s that simple. Kind of like Dr. Seuss’s Thing One and Thing Two. The only difference between the three different levers is where the effort, load and fulcrum are.


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Are you ready for some ‘vintage Aurora’ video? We thought you’d want to check out one of the first videos she ever made (in her basement with the auto-focus stuck in the ON position). Enjoy!



Download Student Worksheet & Exercises


“Advanced students: Download your First, Second, and Third Class Levers”


First-Class Lever

A first-class lever is a lever in which the fulcrum is located in between the effort and the load. This is the lever that you think of whenever you think of levers. The lever you made in Experiment 1 is a first-class lever. Examples of first-class levers are the see-saw, a hammer (when it’s used to pull nails), scissors (take a look, it’s really a double lever!), and pliers (same as the scissors, a double lever).


First Class Lever Experiment

For this experiment, you’ll need:


  1. A nice strong piece of wood. 3 to 8 feet long would be great if you have it.
  2. A brick, a thick book or a smaller piece of wood (for the fulcrum)
  3. Books, gallons of water or anything heavy that’s not fragile

Be careful with this. Don’t use something that’s so heavy someone will get hurt. Also, be sure not to use something so heavy that you break the wooden lever. Last but not least, be sure to keep your head and face away from the lever. I’ve seen folks push down on the lever and then let go. The lever comes up fast and can pop you pretty hard.


1. Put your fulcrum on the ground.


2. Put your lever on the fulcrum. Try to get your fulcrum close to the middle of the lever.


3. Put some weight on one end of the lever.


4. Now push down on the other side of the lever. Try to remember how hard (how much force) you needed to use to lift the heavy object.


5. Move the fulcrum under the lever so that it is closer to the heavy object.


6. Push down on the other side of the lever again. Can you tell the difference in the amount of force?


7. Move the fulcrum closer still to the heavy object. Feel a difference now?


8. Feel free to experiment with this. Move the fulcrum farther away and closer to the object. What conclusions can you draw?


What you may have found, was that the closer the fulcrum is to the heavy object, the less force you needed to push with to get the object to move. Later we will look at this in greater detail, but first let me tell you about the other types of levers.


Second-Class Lever

The second-class lever is a little strange. In a second-class lever, the load is between the fulcrum and the effort. A good example of this is a wheel-barrow. The wheel is the fulcrum, the load sits in the wheel-barrow bucket and the effort is you. Some more examples would be a door (the hinge is the fulcrum), a stapler, and a nut-cracker.


Second-class Lever Experiment

You need:


  1. A nice strong piece of wood. 3 to 8 feet long would be great if you have it.
  2. A brick, a thick book or a smaller piece of wood (for the fulcrum)
  3. Books, gallons of water or anything heavy that’s not fragile

Again, be careful with this. Don’t use something that’s so heavy someone will get hurt. Also, be sure not to use something so heavy that you break the wooden lever. Last but not least, be sure to keep your head and face away from the lever. I’ve seen folks push down on the lever and then let go. The lever comes up fast and can pop you pretty hard.


1. Put your fulcrum, the book or the brick, whatever you’re using on a nice flat spot.


2. Put the end of your lever on the fulcrum.


3. Put the books or gallon jugs or whatever you’re using for a load, in the middle of the lever.


4. Now, put yourself (the effort) on the opposite end of the lever from the fulcrum.


5. Lift


6. Experiment with the load. Move it towards the fulcrum and lift. Then move it toward the effort and lift. Where is it harder(takes more force) to lift the load, near the fulcrum or far? Where does the load lift the greatest distance, near the fulcrum or far?


Third-Class Lever

This fellow is the oddest of all. The third-class lever has the effort between the load and the fulcrum. Imagine Experiment 1 but this time the fulcrum is at one end of the board, the books are on the other end and you’re in the middle. Kind of a strange way to lift books huh? A few examples of this are tweezers, fishing rods (your elbow or wrist is the fulcrum), your jaw (the teeth crush the load which would be your hamburger), and your arm (the muscle connects between your elbow (fulcrum) and your load( the rest of your arm or whatever you’re lifting)). Your skeletal and muscular system is, in fact, a series of levers!


Third-class Lever Experiment

You need:


  1. A nice strong piece of wood. 3 to 8 feet long would be great if you have it.
  2. A brick, a thick book or a smaller piece of wood (for the fulcrum)
  3. Books, gallons of water or anything heavy that’s not fragile

Again, be careful with this. Don’t use something that’s so heavy someone will get hurt. Also, be sure not to use something so heavy that you break the wooden lever. Last but not least, be sure to keep your head and face away from the lever. I’ve seen folks push down on the lever and then let go. The lever comes up fast and can pop you pretty hard.


1. Put your fulcrum on the ground in a nice flat place.


2. Put your lever on the fulcrum so that the fulcrum is at the very end of the lever.


3. Put your load on the lever at the end farthest from the fulcrum.


4. Now, put yourself (the effort) in the middle of the lever.


5. Lift. You may need someone to hold down the lever on the fulcrum


6. Experiment with the effort (you). Move towards the fulcrum and lift the load Then move toward the load and lift. Where is it harder(takes more force) to lift the load, near the fulcrum or far? Where does the load lift the greatest distance, near the fulcrum or far?


We’ve had a lot of fun levering this and levering that but now we have to get to the point of all this simple machine stuff. Work equals force times distance, right? Well, what have you been doing all this time with these levers? You’ve been moving something (the load) a distance against a force (gravity). You’ve been doing work. You’ve been exerting energy. See how it all ties in nicely?


In experiments 1,2 and 3, I wanted you to notice how much force you exerted and how much the load moved. You may have noticed that when the force was small (it was very easy to lift) the load moved a very small distance. On the other hand, when the force was large (hard to lift), the load moved a greater distance. Let me point your attention to one more thing and then we’ll play with this.


When the force used to lift the load was small, you moved the lever a large distance. When the force used to lift the load was great you moved the lever a small distance. Remember, work=force x distance. There is work done on both sides of the lever. The effort (you in this case) pushes the lever a distance against a force…work is done. The load also moves a distance against a force so there too…work is done.


Now, here’s the key to this that I hope you can see in the next experiment. Work in is equal to work out. The work you do on one side of the lever (work in), is equal to the work that happens to the load (work out). Let’s do a quick bit of math for an example. Phillip wants to move a 10 kg (22 lb.)box. He uses a lever and notices that when he lifts the box .1meter (4 inches) he has to push the lever down 1 meter with a force of 1 kg. Now let’s do some math. (Officially we should convert kilograms (a unit of mass) to Newtons (a unit of force) so that we can work in Joules which is a unit of work. However, we’ll do it this way so you can see the relationship more easily.)


Phillip’s work (the work in) = 1 kg x 1 m = 1


Work on the bowling ball (the work out) = 10 kg x .1 m = 1


Work in equals work out! Later in this energy unit, you’ll learn about energy efficiency. At that point, you’ll see that you never get all the energy you want from the energy you put in. Some energy is lost to sound and some to heat. A lever is incredibly efficient but you may still see, in your measurements, that the energy in is greater than the energy you get out.


For Advanced Students:

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Speaking of your measurements…let’s make some. Open up your science journal and record the type of lever, weight, and location information for your different trial runs. Take a look at your data – can you figure out how much weight you’d need to lift your parents?


Let’s see if we can figure this out. For a 10′ long beam with the fulcrum in the exact center, you can lift as much as you weigh. For example, if you weigh 100 pounds, you can lift some sitting on the other end, as long as they weigh 100 pounds or less. If you slide the beam and move the fulcrum so that the longer end is on your side, you can lift more than you weigh.


So if there’s 7 feet of beam on Alice’s side and only 3 feet on Bob’s end, you can easily figure this out with a little math (and principles of torque). Here’s what you do:


(Alice’s Weight) * (Distance from Alice to the Fulcrum) = (Alice’s Lifting Ability) * (Distance from Bob to the Fulcrum)


If Alice weighs 100 pounds and when standing on the 7-foot end of the see-saw, she barely can lift Bob, let’s find out how much Bob weighs.


(100 pounds) (7 feet) = (Alice’s Lifting Ability) * (3 feet)


700 / 3 = Alice’s Lifting Ability, and since she can just barely lift Bob…


Bob weighs 233 pounds!


Now can you figure out how much lever arm distance you need to lift your parents? If Mom and Dad together weigh 300 pounds, and you have a 10′ long beam and you weigh 100 pounds, let’s find the fulcrum distance you’d need to lift them. Let’s put your algebra to use here:


Let’s make ‘x’ the distance from you to the fulcrum. This makes the distance from your parents to the fulcrum 10′ – x. (If you’re 4 feet from the fulcrum, that means your parents are 6′, right?)


(100 pounds) (x) = (300 pounds) (10′ – x)


100 x = 3000 – 300 x


400 x = 3000


x = 3000 / 400


Solve for x and you’ll find that the distance from you to the fulcrum is 7.5 feet!


Exercises Answer the questions below:


  1. What is the best definition for a simple machine?
    1. A machine with less than three parts
    2. A machine with a simple name
    3. A machine that changes the direction or amount of a force
    4. A machine that helps you do work quickly
  2. What are the three parts of a lever? Circle all that apply:
    1. Fulcrum
    2. Weight
    3. Load
    4. Effort
  3. Name two examples of levers that you could find in your house:
  4. What are the types of levers called?
    1. Three tiers
    2. First, second, and third class
    3. Poor, rich, and middle
    4. Forty-five and ninety-nine percenters

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Roller Skate Belts

Saturday October 17, 2009
This isn't strictly a 'levers' experiment, but it's still a cool demonstration about simple machines, specifically how pulleys are connected with belts.

Take a rubber band and a roller skate (not in-line skates, but the old-fashioned kind with a wheel at each corner.) Lock the wheels on one side together by wrapping the rubber band around one wheel then the other.  Turn one wheel and watch the other spin.

Now crisscross the rubber band belt by removing one side of the rubber band from a wheel, giving it a half twist, and replacing it back on the wheel.  Now when you turn one wheel, the other should spin the opposite direction. Here's a quick video on what to expect:

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Download Student Worksheet [/am4show]

Hydraulic Pneumatic Earth Mover

Saturday October 17, 2009

When people mention the word “hydraulics”, they could be talking about pumps, turbines, hydropower, erosion, or river channel flow.  The term “hydraulics” means using fluid power, and deals with machines and devices that use liquids to move, lift, drive, and shove things around.


Liquids behave in certain ways: they are incompressible, meaning that you can’t pack the liquid into a tighter space than it already is occupying.


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If you’ve ever filled a tube partway with water and moved it around, you’ve probably noticed that the water level will remain the same on either side of the tube.


However, if you add pressure to one end of the tube (by blowing into the tube), the water level will rise on the opposite side. If you decrease the pressure (by blowing across the top of one side), the water level will drop on the other side.


In physics, this is defined through Pascal’s law, which tells us how the pressure applied to one surface can be transmitted to the other surface. As liquids can’t be squished, whatever happens on one surface affects what occurs on the other.  Examples of this effect include siphons, water towers, and dams. Scuba divers know that as they dive 30 feet underwater, the pressure doubles. This effect is also show in hydraulics – and more importantly, in the project we’re about to do!


But first, let’s understand what’s happening with liquids and pressure:


Here’s an example: If you fill a glass full to the brim with water, you reach a point where for every drop you add on top, one drop will fall out.  You simply can’t squish any more water molecules into the glass without losing at least the same amount. Excavators, jacks, and the brake lines in your car use hydraulics to lift huge amounts of weight, and the liquid used to transfer the force is usually oil at 10,000 psi.


Air, however, is compressible.  When car tires are inflated, the hose shoves more and more air inside the tire, increasing the pressure (amount of air molecules in the tire).  The more air you stuff into the tire, the higher the pressure rises.  When machines use air to lift, move, spin, or drill, it’s called “pneumatics”. Air tools use compressed air or pure gases for pneumatic power, usually pressurized to 80-100 psi.


Different systems require either hydraulics or pneumatics.  The advantage to using hydraulics lies in the fact that liquids are not compressible. Hydraulic systems minimize the “springy-ness” in a system because the liquid doesn’t absorb the energy being transferred, and the working fluids can handle much heavier loads than compressible gases.  However, oil is flammable, very messy, and requires electricity to power the machines, making pneumatics the best choice for smaller applications, including air tools (to absorb excessive forces without injuring the user).


We’re going to build our own hydraulic-pneumatic machine.  Here’s what you need to do:


Materials:


  • plastic cup
  • 20 tongue-depressor-size popsicle sticks
  • 6 syringes (anything in the 3-10mL size range will work)
  • 6 brass fasteners
  • 5’ of flexible tubing (diameter sized to fit over the nose of your syringes)
  • four wheels (use film canister lids, yogurt container lids, milk jug lids, etc.)
  • 4 rubber bands
  • two naked (unwrapped) straws
  • skewers that fit inside your straws
  • hot glue gun (with glue sticks)
  • sharp scissors or razor (get adult help)
  • drill with small drill bits (you’ll be drilling a hole large enough to fit the stem of a brass fastener)

earthmover


Let’s play with these different ideas right now and really “feel” the difference between hydraulics and pneumatics. Connect two syringes with a piece of flexible tubing.  Cut the tubing into three equal-sized pieces and use one to experiment with.  Shove the plunger on one syringe to the “empty”, and leave the other in the “filled” position before connecting the tubing.  What happens when you push or lift one of the plungers? Is it quick to respond, or is there “slop” in the system?


Now remove both plungers and, leaving the tubing attached, fill the system with water to the brim on both ends (this is a good bath-time activity!).  Keep the open ends of the syringes at the same level as you fill them.  What happens if you lower one of the syringes? What happens when you raise it back up?  Is there now air in your system?


Fill your syringe-tube system up with water again, keeping the plungers at the same height as you work.  Insert one of the plungers into one of the syringes and play with the levels of the syringes again, lifting one and lowering the other.  Now what happens, or doesn’t happen?


Why does that work? Because both syringes are open to the atmosphere, they both have equal amounts of air pressure pushing down on the surface of the water.  When you raise one syringe higher than the other, you have increased the elevation head of higher syringe, which works to equalize the water levels in the two syringes (thus shoving water out of the lower syringe).  Elevation head is due to the fluid’s weight (gravitational force) acting on the fluid and is related to the potential energy of the raised syringe (which increased with elevation).


Now connect your plungers into a fully hydraulic system:  Push the plunger all the way down to expel the water from one of the syringes (water should leak all over the place from the open syringe).  Now add the second plunger to the open syringe and push the plunger down halfway.  What happens?  You have just made a hydraulic system!


Are you ready to build it into a three-axis machine?  Then click the play button below:



Download Student Worksheet


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The SeeSaw

Saturday October 17, 2009

We’re going to use everyday objects to build a simple machine and learn how to take data. Sadly, most college students have trouble with these simple steps, so we’re getting you a head start here. The most complex science experiments all have these same steps that we’re about to do… just on a grander (and more expensive) scale. We’re going to break each piece down so you can really wrap your head around each step. Are you ready to put your new ideas to the test?


This experiment is for Advanced Students.


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You need:


  • A wooden ruler or a paint stick for the lever
  • Many pennies, quarters, or washers (many little somethings of the same mass)
  • A spool, eraser, pencil (anything that can be your fulcrum)
  • A ruler (to be your um….ruler)
  • Paper cups
  • Optional: A scale that can measure small amounts of mass (a kitchen scale is good)


Download Student Worksheet & Exercises


1. Tape one paper cup to each end of lever. (This allows for an easy way to hold the pennies on the lever.)


2. Set your fulcrum on the table and put your lever (ruler or paint stick) on top of it. Try to get the ruler to balance on the fulcrum.


3. Put five pennies on one side of your lever.


4. Now, put pennies, one at a time on the other side of your lever, this is your effort. Keep adding pennies until you get your lever to come close to balancing. Try to keep your fulcrum in the same place on your lever. You may even want to tape it there.


5. Count the pennies on the effort side and count the pennies on the load side. If you have a scale, you can weigh them as well. With the fulcrum in the middle you should see that the pennies/mass on both sides of the lever are close to equal.


6. This part’s a little tricky. Measure how high the lever was moved. On the load side, measure how far the lever moved up and on the effort side measure how far the lever moved down. Be sure to do the measuring at the very ends of the lever.


7. Write your results in your science journal as shown in the video.


8. Remove the pennies and do it all over again, this time move the fulcrum one inch (two centimeters) closer to the load side.


9. Continue moving the fulcrum closer to the load until it gets too tough to do. You’ll probably be able to get it an inch or two (two to four centimeters) from the load.


10. If you didn’t use a scale feel free to stop here. Don’t worry about the “work in” and “work out” parts of the table. Take a look at your table and check out your results. Can you draw any conclusions about the distance the load moved, the distance the effort moved, and the amount of force required to move it?


11. If you used a scale to get the masses you can find out how much work you did. Remember that work=force x distance. The table will tell you how to find work for the effort side (work in) and for the load side (work out). You can multiply what you have or if you’d like to convert to Joules, which is a unit of work, feel free to convert your distance measurements to meters and your mass measurements to Newtons. Then you can multiply meters times Newtons and get Joules which is a unit of work.


1 inch = .025 meters


1 cm = .01 meter


1 ounce =0.278 Newtons


1 gram = 0.0098 Newtons


By taking a look at your data and by all the other work we did this lesson, you can see the beautiful switcheroo of simple machines. Simple machines sacrifice distance for force. With the lever, the farther you had to push the lever, the less force had to be used to move the load.


The work done by the effort is the same as the work done on the load. By doing a little force/distance switcheroo, moving the load requires much less force to do the work. In other words, it’s much easier. Anything that makes work easier gets a thumbs up by me! Hooray for simple machines!


Exercises


  1. What is work?
    1. Force against an object
    2. Force over distance
    3. 9 hours and sweat
    4. Energy applied to an object
  2. What is the unit we use to measure energy?
    1. Newton
    2. Watt
    3. Joule
    4. Horsepower
  3. Describe a first class lever using one example.

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What’s a Joule?

Saturday October 17, 2009

This experiment is for Advanced Students. We’re going to really get a good feel for energy and power as it shows up in real life. For this experiment, you need:


  • Something that weighs about 100 grams or 4 ounces, or just grab an apple.
  • A meter or yard stick

This might seem sort of silly but it’s a good way to get the feeling for what a Joule is and what work is.
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Download Student Worksheet & Exercises


1. Grab your 100 gram object, put it on a table.


2. Now lift it off the table straight up until you lift it one meter (one yard).


3. Lift it up and down 20 times.


A 100 gram object takes about one Newton of force to lift. Since it took one Newton of force to lift that object, how much work did we do? Remember work = force x distance so in this case work = 1 Newton x 20 meters or work = 20 Joules.


You may ask “but didn’t we move it 40 meters, 20 meters up and 20 down?” That’s true, but work is moving something against a force. When you moved the object down you were moving the object with a force, the force of gravity. Only in lifting it up, are you actually moving it against a force and doing work. Four Joules are about 1 calories so we did 5 calories of work.


“Wow, I can lift an apple 20 times and burn 5 calories! Helloooo weight loss!” Well…not so fast there Richard Simmons. When we talk about calories in nutrition we are really talking about kilo calories. In other words, every calorie in that potato chip is really 1000 calories in physics. So as far as diet and exercise goes, lifting that apple actually only burned .005 calories of energy,…rats.


It is interesting to think of calories as the unit of energy for humans or as the fuel we use. The average human uses about 2000 calories (food calories that is, 2,000,000 actual calories) a day of energy. Running, jumping, sleeping, eating all uses calories/energy. Running 15 minutes uses 225 calories. Playing soccer for 15 minutes uses 140 calories. (Remember those are food calories, multiply by 1000 to get physics calories). This web site has a nice chart for more information: Calories used in exercise.


Everything we eat refuels that energy tank. All food has calories in it and our body takes those calories and converts them to calories/energy for us to use. How did the food get the energy in it? From the sun! The sun’s energy gives energy to the plants and when the animals eat the plants they get the energy from the sun as well.


So, if you eat a carrot or a burger you are getting energy from the sun! Eating broccoli gives you about 50 calories. Eating a hamburger gives you about 450 calories! We use energy to do things and we get energy from food. The problem comes when we eat more energy than we can use. When we do that, our body converts the energy to fat, our body’s reserve fuel tank. If you use more energy then you’ve taken in, then your body converts fat to energy. That’s why exercise and diet can help reduce your weight.


Let’s take the concept of work a little bit farther. If Bruno carries a 15 pound bowling ball up a 2 meter (6 foot) flight of stairs, how much work does he do on the bowling ball? It takes 66 Newtons of force to lift a 15 pound bowling ball 1 meter. Remember work = force x distance.


So, work = 66 Newtons x 2 meters. In this case, Bruno does 132 Joules of work on that bowling ball. That’s interesting, but what if we wanted to know how hard poor Bruno works? If he took a half hour to go up those stairs he didn’t work very hard, but if he did it in 1 second, well then Bruno’s sweating!


That’s the concept of power. Power is to energy like miles per hour is to driving. It is a measure of how much energy is used in a given span of time. Mathematically it’s Power = work/time. Power is commonly measured in Watts or Horsepower. Let’s do a little math and see how hard Bruno works.


In both cases mentioned above Bruno, does 132 Joules of work, but in the first case he does the work in 30 minutes (1800 seconds) and in the last case he does it in 1 second. Let’s first figure out Bruno’s power in Watts. A Watt is 1 Joule/second so:


For the half hour Bruno’s Power = 132 Joules/1800 seconds = .07 Watts


For the second Bruno’s Power = 132 joules/1 second = 132 Watts


You can see that the faster you exert energy the more power you use. Another term for power is horsepower. You may have heard the term horsepower in car ads. The more powerful car can exert more energy faster, getting the car moving faster. A Dodge Viper has 450 horsepower which can accelerate a 3,300 pound car from 0 to 60 mph in 4.1 seconds…WOW!


One horsepower is 745 Watts or one Watt is .001 horsepower. So converting Watts to horsepower poor Bruno exerts:


.07 x .001 = .00007 horsepower over the half hour


132 x .001 = .132 horsepower over the second (not exactly a Dodge Viper!)


Exercises


  1. If something has a weight of 2 Newtons and is moved half a meter, how many Joules of energy are used? Show your work.
  2. What is the source of all this energy we’re working with here?
  3. It doesn’t count as work when you move the apple back down. Why not?

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Measuring Power

Saturday October 17, 2009

We’re going to practice measuring and calculating real life stuff (because science isn’t just in a textbook, is it?) When I taught engineering classes, most students had never analyzed real bridges or tools before – they only worked from the textbook. So let’s jump out of the words and into action, shall we? This experiment is for Advanced Students.


Before we start, make sure you’ve worked your way through this experiment first!


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For this experiment, you need:


  1. Meter or yard stick
  2. A stopwatch or timer
  3. Object

Here’s what you do:



Download Student Worksheet & Exercises


1. Grab your 100 gram object, put it on a table.


2. Now lift it off the table straight up until you lift it one meter (one yard).


3. Start the timer and at the same time start lifting the object up and down 20 times.


4. Stop the timer when you’re done with the 20 lifts.


So, do you have the power of the Dodge Viper? Hmmm, probably not but let’s take a look.


First of all figure out how much work you did. Work = force x distance so take the force you used and multiply that by the distance you moved it. In this case, you can multiply 1 Newton x 20 meters and get 20 Joules of work.


Now figure out how much power you used. Power is work divided by time so take your work (20 Joules) and divide it by how much time it took you to do that work.


For example, if you lifted the block 20 times (doing 20 Joules of work) in 5 seconds, you did 20 Joules/5 seconds = 4 Watts of power. To convert Watts to horsepower we multiply by .001 so in this example, you did 4 x .001 = .004 horsepower. Not exactly vroom vroom!


Exercises


  1. What is work?
    1. Force divided by distance
    2. Force times distance
    3. Energy required for power
    4. Kinetic and potential energy
  2. What is power?
    1. Work divided by time
    2. Work multiplied by time
    3. Energy used in an exercise
    4. Calories over time
  3. How do we measure work? Name one unit.
  4. How do we measure power? Name one unit.

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Mousetrap Car

Saturday October 17, 2009
A super-fast, super-cool car that uses the pent-up energy inside a mouse trap spring to propel a homemade car forward. While normally this is reserved for high school physics classes, it really is a fun and inexpensive experiment to do with kids of all ages.

This is a great demonstration of how energy changes form. At first, the energy was  stored in the spring of the mousetrap as elastic potential energy, but after the trap is triggered, the energy is transformed into kinetic energy as rotation of the wheels.

Remember with the First Law of Thermodynamics: energy can’t be created or destroyed, but it CAN change forms. And in this case, it goes from elastic potential energy to kinetic energy.

There’s enough variation in design to really see the difference in the performance of your vehicle. If you change the size of the wheels for example, you’ll really see a difference in how far it travels. If you change the size of the wheel axle, your speed is going to change. If you alter the size of the lever arm, both your speed and distance will change. It's fun to play with the different variables to find the best vehicle you can build with your materials!

Here's what you need to do this project:

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Materials:

  • Mousetrap (NOT a rat trap)

  • Foam block or piece of cardboard

  • Four old CDs

  • Thin string or fishing line

  • Wood dowel or long, straight piece from a wire coat hanger (use pliers to straighten it)

  • Straw

  • Two wood skewers (that fit inside straw)

  • Hot glue gun

  • Duct tape

  • Scissors

  • Four caps to water bottles

  • Drill

  • Razor with adult help



Since the directions for this project are complex, it’s really best to watch the instructions on the video. Here are the highlights:

1. Tape the dowel to the outside of the wire on the mousetrap car (see image below). When the mousetrap spans closed, the dowel whips through the air along with it in an arc.

2. Attach a length of fishing line to the other end of the dowel. Don’t cut the fishing line yet.

3. Attach one straw near each end of a block of foam using hot glue.

4. Insert a skewer into each straw. Insert a wheel onto each end of the skewer. This is your wheel-axel assembly.

5. The wheels on one side should be close to the straw, the wheels on the other end should have a 1/2” gap.

6. Thread the end of the fishing line around the wheels with the gap as shown in the video.

7. Load the mousetrap car by spinning the back wheels as you set the trap.

8. Trigger the mousetrap with a pen (never use your fingers!). The dowel pulls the fishing line, unrolling it from the axel and spinning the wheels as it opens.

What’s Going On?


Energy has a number of different forms; kinetic, potential, thermal, chemical, electrical, electrochemical, electromagnetic, sound and nuclear. All of which measure the ability of an object or system to do work on another object or system.

In the physics books, energy is the ability to do work. Work is the exertion of force over a distance. A force is a push or a pull.

So, work is when something gets pushed or pulled over a distance against a force. Mathematically:

Work = Force x Distance or W = F d

Let me give you a few examples: If I was to lift an apple up a flight of stairs, I would be doing work. I would be moving the apple against the force of gravity over a distance. However, if I were to push against a wall with all my might, and if the wall never moved, I would be doing no work because the wall never moved. (There was a force, but no distance.)

Another way to look at this, is to say that work is done if energy is changed. By pushing on the non-moving wall, no energy is changed in the wall. If I lift the apple up a flight of stairs however, the apple now has more potential energy then it had when it started. The apple’s energy has changed, so work has been done.

All the different forms of energy can be broken down into two categories: potential and kinetic energy.

My students have nicknamed potential energy the “could” energy. The battery “could” power the flashlight. The light “could” turn on. I “could” make a sound. That ball “could” fall off the wall. That candy bar “could” give me energy.

Potential energy is the energy that something has that can be released. For example, the battery has the potential energy to light the bulb of the flashlight if the flashlight is turned on and the energy is released from the battery. Your legs have the potential energy to make you hop up and down if you want to release that energy (like you do whenever it’s time to do science!). The fuel in a gas tank has the potential energy to make the car move.

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Trebuchet

Saturday October 17, 2009

trebuchet23This experiment is for Advanced Students. For ages, people have been hurling rocks, sticks, and other objects through the air. The trebuchet came around during the Middle Ages as a way to break through the massive defenses of castles and cities. It’s basically a gigantic sling that uses a lever arm to quickly speed up the rocks before letting go. A trebuchet is typically more accurate than a catapult, and won’t knock your kid’s teeth out while they try to load it.


Trebuchets are really levers in action. You’ll find a fulcrum carefully positioned so that a small motion near the weight transforms into a huge swinging motion near the sling. Some mis-named trebuchets are really ‘torsion engines’, and you can tell the difference because the torsion engine uses the energy stored in twisted rope or twine (or animal sinew) to launch objects, whereas true trebuchets use heavy counterweights.


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This is a serious wood-construction project. If you have access to scrap wood and basic tools (and glue!), you have everything you need to build this project. You will need to find heavy objects (like rocks or marbles) for the weights.


We want kids to discover that science isn’t in the special parts that come with a kit, but rather in the imagination and skill of the kid building it. We strive to avoid parts that are specially made just for a kit, molded plastic pieces, etc. and instead use parts that any kid could buy from the store. This means that kids can feel free to change things around, use their own ideas to add improvements and whatever else their imagination can come up with. So on this note, let’s get started.


WARNING: This project requires the use of various hand tools. These tools should only be used with adult supervision, and should not be used by children under 12 years of age.


Tools you’ll need:


  •   Hammer
  •   Electric drill with ¼” bit
  •   Hot glue gun & glue sticks
  •   Measuring tape or ruler
  •   Hand saw & clamp (or miter box)
  •   Scissors
  •   Screwdriver (flathead) or wood chisel

Materials:


  • 7 pieces of ½” x ½” x 24″ pieces of wood stock
  • 2 pieces of ¾” x 24″ wood
  • 1 piece of 3″ x 24″ wood
  • 18″ Wooden dowel
  • Screw eye
  • Nails
  • String
  • Clear tube
  • Rubber mesh

Note: wood pieces may be slightly larger or smaller than specified. Just use your best judgment when sizing.


From ½” x ½” x 24″ pieces of wood stock cut:


  • 3 pieces 5″ long
  • 2 pieces 9″ long
  • 3 pieces 3-1/2″ long
  • 4 pieces 5-1/2″ long

From the dowel cut:


  • 2 pieces 7″ long
  • 1 piece 4″ long

From the 3″ x 24″ flat piece of wood cut:


  • 2 pieces 3″ long (one of these has a 1″ square notch in it)
  • 2 pieces 5″ long
  • 1 piece 4-1/2″ long

AND…


  • String should be cut into 2 pieces 14-16″ long
  • The pouch is cut from the rubber mesh and is 5″ x 1-1/2″


Advanced Students: Download your Student Worksheet Lab here!


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Unit 4: Energy (Pulleys) Video

Saturday October 17, 2009

By the use of a pulley (otherwise known as a block and tackle), car mechanics lift 600 lb car engines with one hand! Cranes that lift steel girders and thousand pound air conditioning units are basically pulleys! This video gets you started on the right foot. We’ll outline what’s coming up for this week and how to get the most out of our lesson together. Enjoy!



Unit 4: Energy (Levers) Video

Saturday October 17, 2009

So what is this lever thing anyway? Well, at it’s most basic level, it’s a stick and a rock…pretty simple machine huh? The lever is made up of two parts, the lever (the stick part) and the fulcrum (the rock part). Believe it or not, using this very simple machine you can lift hundreds of pounds with your bare hands and very little effort. Let’s try it.


This video gets you started on the right foot. We’ll outline what’s coming up for this week and how to get the most out of our lesson together. Enjoy!


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Electrolysis

Saturday October 10, 2009

This experiment is just for advanced students. If you guessed that this has to do with electricity and chemistry, you’re right! But you might wonder how they work together. Back in 1800, William Nicholson and Johann Ritter were the first ones to split water into hydrogen and oxygen using electrolysis. (Soon afterward, Ritter went on to figure out electroplating.) They added energy in the form of an electric current into a cup of water and captured the bubbles forming into two separate cups, one for hydrogen and other for oxygen.

This experiment is not an easy one, so feel free to skip it if you need to. You don’t need to do this to get the concepts of this lesson but it’s such a neat and classical experiment (my students love it) so you can give it a try if you want to. The reason I like this is because what you are really doing in this experiment is ripping molecules apart and then later crashing them back together.

Have fun and please follow the directions carefully. This could be dangerous if you’re not careful. The image shown here is using graphite from two pencils sharpened on both ends, but the instructions below use wire.  Feel free to try both to see which types of electrodes provide the best results.

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You will need:

  • 2 test tubes or thin glass or plastic something closed at one end. I do not recommend anything wider than a half inch in diameter.
  • 2 two wires, one needs to be copper, at least 12 inches long. Both wires need to have bare ends.
  • 1 cup
  • sodium sulfate OR salt
  • Water
  • One 9 volt battery
  • Long match or a long thin piece of wood (like a popsicle stick) and a match
  • Rubber bands
  • Masking tape

Download Student Worksheet & Exercises
1. Fill the cup with water.

2. Put a tablespoon of salt or sodium sulfate into the water and stir it up. (The salt allows the electricity to flow better through the water.)

2. Put one wire into the test tube and rubber band it to the test tube so that it won’t come out (see picture).

3. Use the masking tape to attach both wires to the battery. Make sure the wire that is in the test tube is connected to the negative (-) pole of the battery and that the other is connected to the positive (+) pole. Don’t let the bare parts of the different wires touch. They could get very hot if they do.

4. Fill the test tube to the brim with the salt water.

5. This is the tricky part. Put your finger over the test tube, turn it over and put the test tube, open side down, into the cup of water. (See picture.)

6. Now put the other wire into the water. Be careful not to let the bare parts of the wires touch.

7. You should see bubbles rising into the test tube. If you don’t see bubbles, check the other wire. If bubbles are coming from the other wire either switch the wires on the battery connections or put the wire that is bubbling into the test tube and remove the other. If you see no bubbles check the connections on the battery.

8. When the test tube is half full of gas (half empty of salt water depending on how you look at it) light the long match or the wooden stick. Then take the test tube out of the water and let the water drain out. Holding the test tube with the open end down, wait for five seconds and put the burning stick deep into the test tube (the flame will probably go out but that’s okay). You should hear an instant pop and see a flash of light. If you don’t, light the stick again and try it another time. For some reason, it rarely works the first time but usually does the second or third.

A water molecule, as you saw before, is two hydrogen atoms and one oxygen atom. The electricity encouraged the oxygen to react with the copper wire leaving the hydrogen atoms with no oxygen atom to hang onto. The bubbles you saw were caused by the newly released hydrogen atoms floating through the test tube in the form of hydrogen gas. Eventually that test tube was part way filled with nothing but pure hydrogen gas.

But how do you know which bubbles are which? You can tell the difference between the two by the way they ignite (don’t’ worry – you’re only making a tiny bit of each one, so this experiment is completely safe to do with a grown up).

It takes energy to split a water molecule. (On the flip side, when you combine oxygen and hydrogen together, it makes water and a puff of energy. That’s what a fuel cell does.) Back to splitting the water molecule - as the electricity zips through your wires, the water molecule breaks apart into smaller pieces: hydrogen ions (positively charged hydrogen) and oxygen ions (negatively charged oxygen). Remember that a battery has a plus and a minus charge to it, and that positive and negative attract each other.

So, the positive hydrogen ions zip over to the negative terminal and form tiny bubbles right on the wire. Same thing happens on the positive battery wire. After a bit of time, the ions form a larger gas bubble. If you stick a cup over each wire, you can capture the bubbles and when you’re ready, ignite each to verify which is which.

If the match burns brighter, the gas is oxygen. If you hear a POP!, the gas is hydrogen. Oxygen itself is not flammable, so you need a fuel in addition to the oxygen for a flame. In one case, the fuel is hydrogen, and hence you hear a pop as it ignites. In the other case, the fuel is the match itself, and the flame glows brighter with the addition of more oxygen.

When you put the match to it, the energy of the heat causes the hydrogen to react with the oxygen in the air and “POP”, hydrogen and oxygen combine to form what? That’s right, more water. You have destroyed and created water! (It’s a very small amount of water so you probably won’t see much change in the test tube.)

The chemical equations going on during this electrolysis process look like this:

A reduction reaction is happening at the negatively charged cathode. Electrons from the cathode are sticking to the hydrogen cations to form hydrogen gas:

2 H+(aq) + 2e- --> H2(g)

2 H2O(l) + 2e- --> H2(g) + 2 OH-(aq)

The oxidation reaction is occurring at the positively charged anode as oxygen is being generated:

2 H2O(l)  --> O2(g) + 4 H+(aq) + 4e-

4 OH-(aq) --> O2(g) + 2 H2O(l) + 4 e-

Overall reaction:

2 H2O(l)  --> 2 H2(g) + O2(g)

Note that this reaction creates twice the amount of hydrogen than oxygen molecules. If the temperature and pressure for both are the same, you can expect to get twice the volume of hydrogen to oxygen gas (This relationship between pressure, temperature, and volume is the Ideal Gas Law principle.)

This is the idea behind vehicles that run on sunlight and water.  They use a solar panel (instead of a 9V battery) to break apart the hydrogen and oxygen and store them in separate tanks, then run them both back together through a fuel cell, which captures the energy (released when the hydrogen and oxygen recombine into water) and turns the car's motor. Cool, isn't it?

Note: We're going to focus on Alternative Energy in Unit 12 and create all sorts of various energy sources including how to make your own solar battery, heat engine, solar & fuel cell vehicles (as described above), and more!

Exercises

  1. Why are bubbles forming?
  2. Did bubbles form at both wires, or only one? What kind of bubbles are they?
  3. What would happen if you did this experiment with plain water? Would it work? Why or why not?
  4. Which terminal (positive or negative) produced the hydrogen gas?
  5. Did the reaction create more hydrogen or more oxygen?

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The Breaking Point

Sunday October 4, 2009
If you've ever teetered on the edge of a diving board, you know that the board flexes under your weight.  The heavier you are, the more it bends.  The top of the board gets slightly stretched further than the normal length (tension) while the underside gets slightly shorter (compressed). We're going to duplicate this without needing to visit the pool.

We're going to expand on the topic covered in the Tension and Compression section of this article. All you need for this experiment is:
  • a pencil or a craft stick that you don’t mind breaking
  • a pair of hands
[am4show have='p8;p9;p13;p40;' guest_error='Guest error message' user_error='User error message' ] 1. Grab the pencil or the craft stick with one hand on one end of the object and the other hand on the opposite end.

2. Bend the pencil or craft stick a bit, but not too far....yet. Notice how you can bend it quite a bit without it breaking.

3. Now, feel free to bend it slowly until it breaks.



Download Student Worksheet

You have just played with tension, compression and elasticity. When you bent the pencil it had no problem going back to its original shape right? Wood is fairly elastic, meaning it can bend quite a bit before breaking. This comes in quite handy if you happen to be a tree, since you can bend in the wind which allows you to survive most storms without breaking.

Now, let’s look at tension and compression. If you look at the pencil or craft stick that you just broke you may notice that one side of the break may look different then the other side. Tension is when things get pulled apart. Compression is when things get squashed together.

If you bent your pencil towards the ground for example, the molecules along the top of the pencil were pulled apart, and the molecules along the bottom were squashed together. If you didn’t bend too far they just went back to normal when you stopped applying force. However if you bent too far, “SNAP”, the pencil broke in two! Just like objects have an elastic limit that if you go beyond it you will break it, things also have a tension and compression limit. Pull something or push something too far, and you’ll break it. [/am4show]

Moon Sand

Sunday October 4, 2009

A non-Newtonian fluid is a substance that changes viscosity, such as ketchup.  Ever notice how ketchup sticks to the bottom of the bottle one minute and comes sliding out the next?


Think of viscosity as the resistance stuff has to being smeared around.   Water is “thin” (low viscosity); honey is “thick” (high viscosity).  You are about to make a substance that is both (low and high viscosity), depending on what ratio you mix up. Feel free to mix up a larger batch then indicated in the video – we’ve heard from families that have mixed up an entire kiddie pool of this stuff!


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  • cornstarch (about 2 cups)
  • water (about 1 cup)
  • sand (about 2 cups)

Your first step is to create a 2:1 ratio of cornstarch to water (2 cups cornstarch to 1 cup water).  (This is your non-Newtonian fluid.)  Grab it with your fist and it will turn rock-solid and crumble; open your hand and it will flow right between your fingers. It’s both a solid and a liquid (it changes viscosity depending on its environment, which is your hand right now).  By adding sand to this concoction, you can make moon sand.



 
Download Student Worksheet & Exercises


Moon sand is basically clay with a beach twist.  If you’ve ever tried making a sand castle, you know the disappointment of having the structure crumble after hours of work.  Moon sand adds the best properties of clay to the sand for a moldable, sandy texture that’s easy to work with — and it’s dirt cheap to mix up your weight in moon sand.


Your task is to find the perfect ratio of the three ingredients to make this weird substance.  If you have too much water, you’ll get a substance that is both a liquid and a solid (as you did before with the non-Newtonian fluid).  Too much solid, and it crumbles.


Troubleshooting: The smaller the grain of sand you have, the easier it is to form intricate shapes.  If you find white sand, it’ll make better colors when you add food dye to the mixture. Use a large enough bowl and try to keep one hand clean so you can add more (of whatever you need) as you go along.  The ideal mixture is approximately 2 cups sand, 2 cups cornstarch, and 1 cup water, give or take a bit.  Notice how adding just a small amount of water turns it into a liquid, and adding a tiny bit more cornstarch (or sand) makes it crumble as if it were solid?  Take your time to get this mixture just right. (We’ve filled up an entire plastic kiddie pool with this stuff!)
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Lesson 2: Solids (Video)

Friday October 2, 2009

Now, that you’ve spent some quality time with atoms and that wacky electron fellow you have a bit of an understanding of what is inside everything. The next thing you need to know is…what’s everything?



Lesson 1: Atoms & Density (Video)

Friday October 2, 2009

We’re going to study atoms, their parts, as well as how they work together. Are you ready? You can get started by watching this video:


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Microwaving Soap

Friday October 2, 2009

soapWhen you warm up leftovers, have you ever wondered why the microwave heats the food and not the plate? (Well, some plates, anyway.) It has to do with the way microwaves work.


Microwaves generate high energy electromagnetic waves that when aimed at water molecules, makes these molecules get super-excited and start bouncing around a lot.


We see this happen when we heat water in a pot on the stove. When you add energy to the pot (by turning on the stove), the water molecules start vibrating and moving around faster and faster the more heat you add. Eventually, when the pot of water boils, the top layer of molecules are so excited they vibrate free and float up as steam.


When you add more energy to the water molecule, either by using your stove top or your nearest microwave,  you cause those water molecules to vibrate faster. We detect these faster vibrations by measuring an increase in the temperature of the water molecules (or in the food containing water). Which is why it’s dangerous to heat anything not containing water in your microwave, as there’s nowhere for that energy to go, since the electromagnetic radiation is tuned to excite water molecules.


To explain this to younger kids (who might confuse radio waves with sounds waves) you might try this:


There’s light everywhere, some of which you can see (like rainbows) and others that you can’t see (like the infrared beam coming from your TV remote, or the UV rays from the sun that give you a sunburn). The microwave shoots invisible light beams at your food that are tuned to heat up the water molecule.


The microwave radiation emitted by the microwave oven can also excite other polarized molecules in addition to the water molecule, which is why some plates also get hot. The soap in this experiment below will show you how a bar of Ivory soap contains air, and that air contains water vapor which will get heated by the microwave radiation and expand. Are you ready?


Here’s what you need:


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  • bar of Ivory soap
  • microwave (not a new or expensive one)
  • plate (optional)

The following experiment is a quick example of this principle using a naked bar of Ivory soap. The trick is to use Ivory, which contains an unusually high amount of air. Since air contains water moisture, Ivory also has water hidden inside the bar of soap. The microwave will excite the water molecules and your kids will never look at the soap the same way again.



 
Download Student Worksheet & Exercises


Toss a naked bar of Ivory soap onto a glass or ceramic plate and stick it into the microwave (don’t use a new or expensive microwave!) on HIGH for 2-3 minutes. Watch intently and remove when it reaches a “maximum”. Be careful when you touch it after taking it out of the microwave oven – it may still hold steam inside. You can still use the soap and the microwave after this experiment!


Note: Scientists refer to ‘light’ as the visible part of the electromagnetic spectrum, where radio and microwaves are lower energy and frequency than light (and the height of the wave can be the size of a football field). Gamma rays and x-rays are higher energy and frequency than light (these tend to pass through mirrors rather than bounce off them. More on that in Unit 9.)


Exercises


  1.  What is it in your food (and the soap) that is actually heated by the microwave?
  2.  How does a microwave heat things?
  3.  Touch the soap after it has been allowed to cool for a few minutes and record your observations.

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Rock Candy Crystals

Friday October 2, 2009

Crystals are formed when atoms line up in patterns and solidify.  There are crystals everywhere — in the form of salt, sugar, sand, diamonds, quartz, and many more!


To make crystals, you need to make a very special kind of solution called a supersaturated solid solution.  Here’s what that means: if you add salt by the spoonful to a cup of water, you’ll reach a point where the salt doesn’t disappear (dissolve) anymore and forms a lump at the bottom of the glass.


The point at which it begins to form a lump is just past the point of saturation. If you heat up the saltwater, the lump disappears.  You can now add more and more salt, until it can’t take any more (you’ll see another lump starting to form at the bottom).  This is now a supersaturated solid solution.  Mix in a bit of water to make the lump disappear.  Your solution is ready for making crystals.  But how?


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Here’s what you need:


  • pencil or wooden skewer
  • string
  • glass jar (cleaned out pickle, jam or may jars work great)
  • 8 cups of sugar
  • 3 cups water
  • paper clip
  • adult help and a stove
  • food coloring  is optional but fun!

If you add something for the crystals to cling to, like a rock or a stick, crystals can grow.  If you “seed” the object (coat it with the stuff you formed the solution with, such as salt or sugar), they will start forming faster. If you have too much salt (or other solid) mixed in, your solution will crystallize all at the same time and you’ll get a huge rock that you can’t pull out of the jar.  If you have too little salt, then you’ll wait forever for crystals to grow. Finding the right amount takes time and patience.



 
Download Student Worksheet & Exercises


1. If you plan on eating the sugar crystal when you’re done you probably want to boil water with the jar and the paper clip in it to get rid of any nasties. Be careful, and don’t touch them while they are hot.


2. Tie one end of the string to the pencil and the opposite end to the paper clip.  (You can alternatively use a skewer instead of a piece of string to make it look more like the picture above, but you’ll need to figure out a way to suspend the skewer in the jar without touching the sides or bottom of the jar.)


3. Wet the string a bit and roll it in some sugar. This will help give the sugar crystals a place to start.


4. Place the pencil across the top of the jar. Make sure the clip is at the bottom of the jar and that the string hangs straight down into the jar. Try not to let the sting touch the side of the jar.


5. Heat 3 cups of water to a boil


6. Dissolve 8 cups of sugar in the boiling water (again be careful!). Stir as you add. You should be able to get all the sugar to dissolve. You can add more sugar until you start to see undissolved bits at the bottom of the pan.  If this happens, just add a bit of water until they disappear.


7. Feel free to add some food coloring to the water.


rockcandy8. Pour the sugar water into the jar. Put the whole thing aside in a quiet place for 2 days to a week. You may want to cover the jar with a paper towel to keep dust from getting in.


You should see crystals start to grow in about 2 days. They should get bigger and bigger over the few days. Once you’re happy with how big your crystals get, you can eat them! It’s nothing but sugar! (Be sure to brush your teeth!)  This one (left) us about 6 months old.


There you go! Next time you hold a pencil, throw a ball, or put on a shoe try to keep in mind that what you’re doing is using an object that is made of tiny strange atoms all held tightly together by their bonds.


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Penny Crystal Structure

Friday October 2, 2009

penny-structureThe atoms in a solid, as we mentioned before, are usually held close to one another and tightly together. Imagine a bunch of folks all stuck to one another with glue. Each person can wiggle and jiggle but they can’t really move anywhere.


Atoms in a solid are the same way. Each atom can wiggle and jiggle but they are stuck together. In science, we say that the molecules have strong bonds between them. Bonds are a way of describing how atoms and molecules are stuck together.


There’s nothing physical that actually holds them together (like a tiny rope or something). Like the Earth and Moon are stuck together by gravity forces, atoms and molecules are held together by nuclear and electromagnetic forces. Since the atoms and molecules come so close together they will often form crystals.


Try this experiment and then we will talk more about this:
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Here’s what you need:


  • 50 pennies
  • ruler


 
Download worksheet and exercises


Lay about 20-50 pennies on the table so that they are all sitting flat on the table. Now, use the ruler (or your hand) to push the pennies toward one another so that you have one big glob of pennies on the table all touching one another. Don’t push so hard that they pile on top of one another. Just get one nice big flat blob of pennies.


Pretty simple huh? However, take a look at the pennies, do you notice anything? You may notice that the pennies form patterns. How could that happen? You just shoved them together you didn’t lay them out in any order. Taa daa! That’s what often happens when solids form.


The molecules are pulled so close to one another that they will form patterns, also known as matrices. These patterns are very dependent on the shape of the molecule so different molecules have a tendency to form different shaped crystals. Salt has a tendency to be “cubey”. Go take a look… and you’ll find that they are like little blocks!


Water has a tendency to from triangle or hexagon shapes which is why snowflakes have six sides. Your pennies also form a hexagon shape. Solids don’t always form crystals but they are more common than you might think. A solid that’s not in a crystalline form is called amorphous. Before you put your pennies away I want you to notice one more thing.


Here’s what you do:


1. Take your pennies and lay them flat on the table.


2. Push them together so they all touch without overlapping.


3. Place your ruler on the right hand side of your penny blob so that it’s touching the bottom half of your pennies.


4. Slowly push the ruler to the left and watch the pennies.


You may have noticed that the penny “crystal” split in quite a straight line. This is called cleavage. Since crystals form patterns the way they do they will tend to break in pretty much the same way you saw your pennies break.


Break an ice cube and take a look. You may see many straight sections. This is because the ice molecules “cleave” according to how they formed. The reason you can write with a pencil is due to this concept. The pencil is formed of graphite crystal. The graphite crystal cleaves fairly easily and allows you to write down your amazing physics discoveries!


(The image here is a graphite crystal.) [/am4show]


Laundry Soap Crystals

Friday October 2, 2009

Can we really make crystals out of soap?  You bet!  These crystals grow really fast, provided your solution is properly saturated.  In only 12 hours, you should have sizable crystals sprouting up.


You can do this experiment with either skewers, string, or pipe cleaners.  The advantage of using pipe cleaners is that you can twist the pipe cleaners together into interesting shapes, such as a snowflake or other design.  (Make sure the shape fits inside your jar.)


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Here’s what you need:


  • pipe cleaners (or string or skewer)
  • cleaned out pickle, jam, or mayo jar
  • water
  • borax (AKA sodium tetraborate)
  • adult help, stove, pan, and stirring spoon

Here’s what you do:


1. Cut a length of string and tie it to your pipe cleaner shape; tie the other end around a pencil or wooden skewer. You want the shape suspended in the jar, not touching the bottom or sides.


2. Bring enough water to fill the jar (at least 2 cups) to a boil on the stove (food coloring is fun, but entirely optional).


3. Add 1 cup of borax (aka sodium tetraborate or sodium borate) to the solution, stirring to dissolve. If there are no bits settling to the bottom, add another spoonful and stir until you cannot dissolve any more borax into the solution. When you see bits of borax at the bottom, you’re ready.  (You’ll be adding in a lot of borax, which is why we asked you to get a full box). You have made a supersaturated solution.  Make sure your solution is saturated, or your crystals will not grow.


4. Wait until your solution has cooled to about 130oF (hot to the touch, but not so hot that you yank your hand away). Pour this solution (just the liquid, not the solid bits) into the jar with the shape.  Put the jar in a place where the crystals can grow undisturbed overnight, or even for a few days.  Warmer locations (such as upstairs or on top shelves) is best.



Download worksheet and exercises


DO  NOT EAT!!! Keep these crystals out of reach of small kids, as they look a lot like the Rock Candy Crystals.


Here are photos from kids ages 2, 7, 9 that made their own! Great job to the Fluker Family!!


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Plasma Grape

Friday October 2, 2009

CAUTION!! Be careful with this!! This experiment uses a knife AND a microwave, so you’re playing with things that slice and gets things hot. If you’re not careful you could cut yourself or burn yourself. Please use care!


We’re going to create the fourth state of matter in your microwave using food.  Note – this is NOT the kind of plasma doctors talk about that’s associated with blood.  These are two entirely different things that just happen to have the same name.  It’s like the word ‘trunk’, which could be either the storage compartment of a car or an elephant’s nose.  Make sense?


Plasma is what happens when you add enough energy (often in the form of raising the temperature) to a gas so that the electrons break free and start zinging around on their own.  Since electrons have a negative charge, having a bunch of free-riding electrons causes the gas to become electrically charged.  This gives some cool properties to the gas.  Anytime you have charged particles (like naked electrons) off on their own, they are referred to by scientists as ions.  Hopefully this makes the dry textbook definition make more sense now (“Plasma is an ionized gas.”)


So here’s what you need:


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  • microwave (not a new or expensive one)
  • a grape
  • a knife with adult help


 
Download Student Worksheet & Exercises


1. Carefully cut the grape almost in half. You want to leave a bit of skin connecting the two halves.


2. Open the grape like a book. In other words, so that the two halves are next to one another still attached by the skin.


3. Put the grape into the microwave with the outside part of the grape facing down and the inside part facing up.


4. Close the door and set the microwave for ten seconds. You may want to dim the lights in the room.


s2You should see a bluish or yellowish light coming from the middle section of the grape. This is plasma! Be careful not to overcook the grape. It will smoke and stink if you let it overcook. Also, make sure the grape has time to cool before taking it out of the microwave.


Other places you can find plasma include neon signs, fluorescent lights, plasma globes, and small traces of it are found in a flame.


Note: This experiment creates a momentary, high-amp short-circuit in the oven, a lot like shorting your stereo with low-resistance speakers. It’s not good to operate a microwave for long periods with little to nothing in them.  This is why we only do it for a few seconds. While this normally isn’t a problem in most microwaves, don’t do this experiment with an expensive microwave or one that’s had consistent problems, as this might push it over the edge.


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Pile It In

Friday October 2, 2009

emperorpenguinsDensity is basically how tightly packed atoms are. Mathematically, density is mass/volume. In other words, it is how heavy something is, divided by how much space it takes up. If you think about atoms as marbles (which we know they’re not from the last lessons but it’s a useful model), then something is more dense if its marbles are jammed close together.


For example, take a golf ball and a ping pong ball. Both are about the same size or, in other words, take up the same volume. However, one is much heavier, has more mass, than the other. The golf ball has its atoms much more closely packed together than the ping pong ball and as such the golf ball is denser.


This experiment builds on the Play With Your Food experiment, so we’ll be learning more about density.  Are you ready?


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Gather your materials:


  • small paper cups
  • a scale that measures small masses (a kitchen scale is good)
  • bunches of different small stuff (pennies, cereal, marbles, etc.)
  • a little water and/or other liquids (milk, syrup, etc.)
  • pencil, paper
  • measuring cup (optional)
  • container that’s larger and deeper then the small paper cup (optional)

1. Put a line with a pencil on the inside and on the outside of the paper cup about half an inch (centimeter) from the top.


2. Fill the cup to the line with whatever kind of stuff you’re using.


3. Weigh the cup and record its mass.


4. Empty the cup and fill it with something else. Record its mass as well.


5. Continue until you’ve done at least five different masses.


For advanced students:

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The following steps are optional. They will help you find out the volume of the materials you’re using. I recommend doing this only if the math won’t turn you off to the concept.


6. Take your larger container, fill it to the brim and place it into your bowl.


7. Take your paper cup and push it into the larger container. Push it in until it reaches the line on the outside of your cup. You should have water coming out of your glass and going into your bowl. Pull the paper cup out of the container and pull the container out of the bowl.


8. Take the water in the bowl and pour it into the measuring cup. Write down the measurement. This is the volume of the cup. Since you are using the same volume for each measurement, (you’re filling the cup to the same line each time) you only need to do this once.


9. Lastly, take your masses and divide each one by the volume. This will give you the density of each material.


So, there you go. Density is mass and volume. How heavy is it and how much space does it take up. If something has a great density, its atoms are very tightly packed together.


There’s a great story about Archimedes and density. The story goes that the king gave a crown maker a hunk of gold and the crown maker was supposed to make a crown using all the gold. Later the king got the crown but, being suspicious, wondered if the crown maker really used all the gold or if he cheated and kept some of it.


Supposedly the king was really bothered by this and felt he needed to find out. He went to Archimedes and asked him to find out if, indeed, he had been cheated or not. At the time, this was a very difficult question. Archimedes knew how heavy it should be if it was a certain volume, but only knew how to get the volume by multiplying length x width x height. How do you do that with an ornate crown? Needless to say the king was against smashing the crown into a cube!


The story goes that this problem possessed Archimedes and he spent so much time thinking about it that he rarely ate, rarely slept and never bathed! Supposedly, that behavior wasn’t that uncommon for him when he was tackling tough problems. Finally his servants, who could no longer stand it, dragged him kicking and screaming to the bath.


The story goes that Archimedes noticed, as he slipped into the bath, that the water rose around him. He discovered that the water he displaced was a way to measure his volume and lo and behold the same method could be used to measure the volume of the crown! Supposedly, he was so excited about this that he jumped out of the tub and ran through the streets stark naked yelling “Eureka! Eureka!” Which means “I found it! I found it!”. He used this method on the crown and to the king’s disappointment (and the crown maker’s too) the crown was indeed missing some gold.


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Quick & Easy Density

Friday October 2, 2009

Density is basically how tightly packed atoms are. (Mathematically, density is mass divided by volume.) For example, take a golf ball and a ping pong ball. Both are about the same size or, in other words, take up the same volume.


However, one is much heavier, has more mass, than the other. The golf ball has its atoms much more closely packed together than the ping pong ball and as such the golf ball is denser.


These are quick and easy demonstrations for density that use simple household materials:
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Density Jar

You will need to find:


  • glass jar
  • water
  • vegetable oil
  • liquid dish soap
  • honey
  • corn syrup
  • molasses
  • rubbing alcohol
  • lamp oil (optional)

Fill a clear glass partway with water. Drizzle in cooking oil. What do you see happening? Try adding in liquid dish soap (make sure it’s a different color form the water and the oil for better visibility.)


What else can you add in? What about honey, corn syrup, molasses, rubbing alcohol, or lamp oil? Use a turkey baster to help you pour the liquids in very slowly so they don’t mix. You’ll get the best results if you start with the heaviest liquids.



 
Download Student Worksheet & Exercises


Hot & Cold Swirl

To clearly illustrate how hot and cold air don’t mix, find two identical glasses.  Fill one glass to the brim with hot water.  Add a drop or two of red food coloring and watch the patterns.  Now fill the other glass to the top with very cold water and add drops of blue dye.  Do you notice a difference in how the food coloring flows?


Get a thick sheet of heavy paper (index cards work well) and use it to cap the blue glass.  Working quickly, invert the glass and stack it mouth-to-mouth with the red glass.  This is the tricky part: When the glasses are carefully lined up, remove the card.  Is it different if you invert the red glass over the blue?


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Play With Your Food

Friday October 2, 2009
This is a simple experiment that really shows the relationship of mass, volume, and density.  You don't need anything fancy, just a piece of bread.  If you do have a scale that can measure small masses (like a kitchen scale), bring it out, but it is not essential.

Here's what you do: [am4show have='p8;p9;p13;p40;' guest_error='Guest error message' user_error='User error message' ]

1. Grab a piece of bread.

2. If you have a scale, weigh the bread to get the mass of the bread.

3. Now, have a little fun and squish the bread into the smallest ball you can!

4. Check the weight (mass) again.

Soooo, what happened? The bread had the same mass before and after squishification right? But did it have the same density? Nope. You, very cleverly and with great strength squeezed those bread atoms closer together. So the bread ball, had a much higher density than the slice of bread did. Same mass, different volume.

Download Student Worksheet [/am4show]

Atomic Facts

Friday October 2, 2009

A gram of water (about a thimble of water) contains 1023 atoms. (That’s a ‘1’ with 23 zeros after it.) That means there are 1,000,000,000,000,000,000,000,000 atoms in a thimble of water! That’s more atoms than there are drops of water in all the lakes and rivers in the world.


Nearly all the mass of an atom is in its nucleus which occupies less than a trillionth of the volume of the atom. They are very dense. If you could pack nuclei like marbles, into something the size of a large pea, they would weigh about a billion tons! That’s 2,000,000,000,000 pounds! More than the weight of 20,000 battle ships! That’s a heavy pea!


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The distance from the nucleus to the electron is 100,000 times the diameter of the nucleus itself. So, if you were to somehow blow up a nucleus to be the size of a golf ball, the electron would be 8,300 feet away or more than 1.5 miles from the golf ball. If you put that golf ball on the ground, you would need to climb to the top of five and a half Sears Towers to get to the electron!


Danish physicist David Bohr, a famous scientist who won the Nobel Prize in Physics in 1922 for his work with the atomic structure.
Danish physicist David Bohr, a famous scientist who won the Nobel Prize in Physics in 1922 for his work with the atomic structure.

Let’s compare this to the Sun and the Earth. (In the picture on the left, the tiny dot in the left size is the actual size of the Earth. The Earth is really not this close to the sun – we just wanted you to get a feel for the sizes of both.) We’ll be doing more about distances and sizes when we do our lesson in Astronomy, but for now, we’ll just use this quick example:


If you shrank the Sun down to a golf ball, the Earth would only be 9 inches away. Nine inches vs. 1.5 miles! There is 11,000 times more distance (to scale) between the nucleus and an electron than there is between the Sun and the Earth!


Here’s one last example – if you enlarged the hydrogen atom (one proton in the nucleus and one electron in a shell) so that it’s the size of the Earth, the electron would be skimming along on the surface of the Earth while the nucleus (just a proton in this instance) would be only the size of a basketball deep inside the core. The rest, from the core to the surface, is empty space.  (Look out your window – can you even see the curvature of the Earth from where you are?  Probably not – it’s just too vast a distance!)


Are you mind-boggled? What this is basically saying, is that matter is virtually empty. The nucleus, which is incredibly tiny and quite heavy for it’s size, is outrageously far away from its electrons. An atom has almost nothing in it and yet everything we come in contact with is made of this ‘nothing’! I don’t know about you, but I find that fantastic!


We will talk more about this wacky atom thing and we’ll get into more detail about the even wackier electron. In the meantime, try to think about everything as a bunch of atoms. The next time you drink milk, you’re drinking atoms. The next time you feel wind, you’re feeling atoms. A lot of things become a bit clearer if you think of objects as being nothing more than bunches of small particles stuck together.


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Salt & Vinegar Crystals

Friday October 2, 2009

We’re going to take two everyday materials, salt and vinegar, and use them to grow crystals by creating a solution and allowing the liquids to evaporate.  These crystals can be dyed with food coloring, so you can grow yourself a rainbow of small crystals overnight.


The first thing you need to do is gather your materials.  You will need:


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Here’s what you need:


  • 1 cup of warm water
  • 1/4 cup salt (non-iodized works better)
  • 2 teaspoons to 2 tablespoons of vinegar (you decide how much you want to use)
  • a shallow dish (like a pie plate)
  • a porous material to grow your crystals on (like a sponge)

First, mix together the salt, vinegar, and water in a cup.  (You cal alternatively boil the water on the stove and stir in as much salt as the water will dissolve.)  Add the vinegar after you turn off the heat. Next, place your sponge in a bowl and pour the solution over the sponge, submerging the sponge in the solution.  Leave out, undisturbed, until the liquids evaporate, leaving behind a sheet of crystals.



 
Download worksheet and exercises


You can add more liquid carefully to the bowl to continue the growth of your crystals for long after the first solution dries up.  Also, as your crystals grow, dot the sponge with drops of food coloring to crow various colors of crystals.


Although it takes awhile for the crystals to start growing, once they do, they will continue to grow quickly!


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Eggshell Crystals

Friday October 2, 2009

Geodes are formed from gas bubbles in flowing lava. Up close, a geode is a crystallized mineral deposit that is usually very dull and ordinary-looking on the outside.  When you crack open a geode, however, it’s like being inside a crystal cave.  We’ll use an eggshell to simulate a gas bubble in flowing lava.


We’re going to dissolve alum in water and place the solution into an eggshell. In real life, minerals are dissolved in groundwater and placed in a gas bubble pocket.  In both cases, you will be left with a geode.


Note: These crystals are not for eating, just for looking.


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Here’s what you need:


  • clean egg shells
  • alum (check the spice section of the grocery store)
  • food dye
  • water


 
Download worksheet and exercises


This is a continuation of the Laundry Soap and Rock Candy experiments, so make sure you’ve done those before trying this one.


Find a clean half eggshell.  Fill a small cup with warm water and dissolve as much alum in the water as you can to make a saturated solution (meaning that if you add any more alum, it will fall to the bottom and not dissolve).


Fill the eggshells with the solution and set aside.  Observe as the solution evaporates over the next few days.  When the solution has completely evaporated, you will have a homemade geode.  If no crystals formed, then you had too much water and not enough alum in your solution.


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Salt Stalactites

Friday October 2, 2009

This is a continuation of the Laundry Soap and Rock Candy experiments, so make sure you’ve done those before trying this one.


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Here’s what you need:


two clean glass jars
yarn or string
epsom salts
water
tin foil or cook sheet
adult help, sauce pot, and a stove.


Make a supersaturated saturated solution from warm water and Epsom salts (magnesium sulfate).  (Add enough salt so that if you add more, it will not dissolve.)  Fill two empty glass jars with the salt solution.  Space the jars a foot apart on a layer of foil or on a cookie sheet.  Suspend a piece of yarn or string from one jar to the other.  Wait impatiently for about three days.  A stalactite should form from the middle of the string!



 
Download worksheet and exercises


[/am4show]


Water Glass & Metal Crystals

Friday October 2, 2009

This experiment is for advanced students. Water Glass is another name for Sodium Silicate (Na2SiO3), which is one of the chemicals used to grow underwater rock crystal gardens. Metal refers to the metal salt seed crystal you will use to start your crystals growing.  You can use any of the following metals listed.  Note however, that certain metals will give you different colors of crystals.


Your crystals begin growing the instant you toss in the seed crystals.  These crystals are especially delicate and fragile – just sloshing the liquid around is enough to break the crystal spikes, so place your solution in a safe location before adding your seed crystals.


After your garden has finished growing to the height and width you want, simply pour out the sodium silicate solution and replace with fresh water (or no water at all).  Due do the nature of these chemicals, keep out of reach of small children, and build your garden with adult supervision.


Here’s what you need to get:


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  • Clean glass jar
  • Sodium silicate (check shopping list for online ordering)
  • One (or more) of the following for different colors:
    • White – calcium chloride (found on the laundry aisle of some stores)
    • Purple – manganese (II) chloride
    • Blue – copper (II) sulfate (common chemistry lab chemical, also used for aquaria and as an algicide for pools)
    • Red – cobalt (II) chloride
    • Orange – iron (III) chloride


 
Download worksheet and exercises


The seed crystals are metal salts that react with the water/sodium silicate solution to climb upwards in the solution, as the products are less dense than the surrounding solution.


Troubleshooting: If you add too many seed crystals, your solution will turn cloudy and you’ll need to start all over again!  Add your seed crystals sparingly – you can always add more later.


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Lava Lamp

Friday October 2, 2009
We're going to watch how density works by making a simple lava lamp that doesn't need electricity! If you like to watch blob-type shapes shift and ooze around, then this is something you're going to want to experiment with.  but don't feel that you have to use the materials mentioned below - feel free to experiment with other liquids you have around the house, and be sure to let me know what you've found in the comment section below.

All you need is about 10 minutes and a few quick items you already have around the house.  Are you ready?

[am4show have='p8;p9;p13;p40;p68;p79;' guest_error='Guest error message' user_error='User error message' ] Here's what you need to find:
  • empty glass jar with straight sides (if possible)
  • vegetable oil
  • salt
  • water
  • food dye


Fill a water glass halfway with colored water, and add a 1/2" layer of oil on top. Shake salt over the oil layer and watch the lava lamp start to work! You'll see the bottom oil layer move as a salt-oil-drop falls to the bottom of the glass. Over a few minutes, the oil breaks free of the salt and moves back up to rejoin the oil layer on top.



Download Student Worksheet

What's happening? You're actually watching the salt itself fall through the oil. However, the oil sticks to the salt to form a larger object, and since the salt is heavier than oil and water, the whole mess plunks to the bottom of the glass. At the bottom of your cup, the oil breaks free of the salt (eventually) and rises back up. Does it matter if you heat the oil, chill the water, or vice versa? Is there anything that works better than salt?

Going Further: Unscrew the camp and add a broken-up effervescent tablet (like alka-seltzer) to your bottle. Cap it and watch what happens! Did it react with water, oil or both? What if you turn off the lights and shine a flashlight through it? [/am4show]