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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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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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?
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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 Experiment

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.

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:

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This 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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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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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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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 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.

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Here’s what you need to find:

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

Cut a right triangle out of paper so that the two sides of the right angle are 11” and 5 ½” (the hypotenuse – the side opposite the right angle – will be longer than either of these). Find a short dowel or use a cardboard tube from a coat-hanger.  Roll the triangular paper around the tube beginning at the short side and roll toward the triangle point, keeping the base even as it rolls.

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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This is a satisfyingly simple activity with surprising results. Take a tennis ball and place it on top of a basketball… then release both at the same time.

Instant ball launcher!

You’ll find the top ball rockets off skyward while the lower ball hit the floor flat (without bouncing much, if at all). Now why is that? It’s easier to explain than you think…

Remember momentum? Momentum can be defined as inertia in motion. Something must be moving to have momentum. Momentum is how hard it is to get something to stop or to change directions. A moving train has a whole lot of momentum. A moving ping pong ball does not. You can easily stop a ping pong ball, even at high speeds. It is difficult, however, to stop a train even at low speeds.

Mathematically, momentum is mass times velocity, or Momentum=mv.

One of the basic laws of the universe is the conservation of momentum.  When objects smack into each other, the momentum that both objects have after the collision, is equal to the amount of momentum the objects had before the crash. Once the two balls hit the ground, all the larger ball’s momentum transferred to the smaller ball (plus the smaller ball had its own momentum, too!) and thus the smaller ball goes zooming to the sky.

Materials:

• two balls, one significantly larger than the other

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Download Student Worksheet & Exercises

Do you see how using a massive object as the lower ball works to your advantage here?  What if you shrink the smaller ball even more, to say bouncy-ball size?  Momentum is mass times by velocity, and since you aren’t going to change the velocity much (unless you try this from the roof, which has its own issues), it’s the mass that you can really play around with to get the biggest change in your results. So for momentum to be conserved, after impact, the top ball had to have a much greater velocity to compensate for the lower ball ‘s velocity going to zero.

You can also try a small bouncy ball (about the size of a quarter) and a larger bouncy ball (tennis-ball size) and rest the small one on top of the large one. Hold upright as high as you can, then release. If the balls stay put (the small one stays on top of the larger) at impact, the energy transfer will create a SUPER high bounce for the small ball. (Note how high the larger ball bounces when dropped.)

What happens if you try THREE?

Read more about impulse here.

Exercises 

1. What is the mathematical formula for momentum?
2.  Explain momentum in words.
3.  What happens to the momentum of the bottom ball in this experiment?

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This experiment is for advanced students.It’s time for the last lesson of mechanics. After all this time, you now have a good working knowledge of the rules that govern almost all movement on this planet and beyond!! This lesson we get to learn about things crashing into one another!! Isn’t physics fun?! We are going to learn about impulse and momentum.
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Here’s what you need:

• two pennies
• you
• a wall
• wagon and a skateboard
• friends

Momentum

Momentum can be defined as inertia in motion. Something must be moving to have momentum. Momentum is how hard it is to get something to stop or to change directions. A moving train has a whole lot of momentum. A moving ping pong ball does not. You can easily stop a ping pong ball, even at high speeds. It is difficult, however, to stop a train even at low speeds. Mathematically, momentum is mass times velocity, or Momentum=mv. The heavier something is and/or the faster it’s moving the more momentum it has. The more momentum something has, the more force it takes to get it to change velocity and the more force it can apply if it hits something.

Impulse

Now let’s discuss impulse. Impulse is a measure of force and time. Remember, force is a push or a pull, right? Well, impulse is how much force is applied for how much time. Mathematically it’s impulse equals force x time or impulse = Ft.

Think about baseball. When you hit a baseball, do you just smack it with the bat or do you follow through with the swing? You follow through right? Do you see how impulse relates to your baseball swing? If you follow through with your swing, the bat stays in contact with the ball for a longer period of time. This causes the ball to go farther. Follow through is important in golf, bowling, tennis and many sports for the same reason. The longer the force is imparted, the farther and faster your ball will go.

More About Impulse and Momentum

Ok, let’s add impulse and momentum together and see what we get. Impulse changes momentum. If an object puts an impulse on another object, the momentum of both objects will change. If you continue to push on your stalled car, you will change the momentum of the car right? If you are riding your bike while not paying any attention and crash into the back of a parked car, you will put an impulse on the car and you and the car’s momentum will change. (As a kid, I did this pretty often. That’s what you get when you ride and wonder at the same time. Believe me when I tell you that my momentum changed a lot more than the car’s did!!)

In fact, there is a mathematical formula about this impulse and momentum thing. Impulse = change in momentum or Ft = change in mv. Force x time = mass x velocity. Does that sound familiar to anyone? It’s awfully similar to Newton’s second law (F=ma) isn’t it? In fact it’s the same thing.

**Alert, alert serious math here, feel free to skip this.**

F t = m v

Now if we divide both sides by “t” we get F=mv/t. Another way to say v is d/t (distance over time).

So now we have F=m(d/t)/t.

Those two “t’s” together are the same as t² and d/t² is a (acceleration). So what we have now is F=ma!

This Ft = mv is very important, in fact, it can save your life. Seat belts, air bags, crumple zones and other car safety features are based on this formula. When you want to shrink the force of impact, you want to increase the time the impact takes. This is called the collision time. The longer the collision time the longer it takes your momentum to come to zero. Here’s the math.

If you are in a 1000 kg vehicle moving at 30 km/h your momentum is 1000 x 30 or 30,000. Now, lets say you hit a brick wall so your momentum goes from 30,000 to 0 in .5 seconds.

Ft=mv so F(.5) = 30,000 so F= 60,000N! (N is for Newton which is a unit of force. It takes about 1 Newton to lift an apple so this car hits with the force of 60,000 apples! Talk about apple sauce!)

That’s gonna leave a mark! Now lets say that instead of hitting a brick wall you hit a mound of hay and so the impact takes 3 seconds.

Now the formula looks like this: F(3)=30,000 or F= 10,000N.

See the difference, 60,000N versus 10,000N of force. All those safety features, seat belts, helmets, air bags, are designed to increase how long it takes your momentum to come to zero. Newton’s laws to the rescue! Let’s do a couple of experiments here to help this information have more impact (pun intended!).

Quick Momentum Experiment

1. Find a wall.

2. Hit it with your bare fist. Take it easy, just hit it with enough force that you feel the impact.

3. Now put a pillow in front of the wall and hit it with about the same force as you hit it before.

4. With the pillow in front of the wall, you can hit it a little harder if you like but again, don’t go nuts!

What did the pillow do? It slowed the time of impact. Remember our formula Ft=mv. When the momentum of your moving fist struck the wall directly, the momentum was cut to zero instantly and so you felt enough force to hurt a bit. When the pillow was in the way it took longer for your momentum to come to zero. So you could hit the pillow fairly hard without feeling much force. Basically a bike helmet is like a pillow for you head. It slows the time of impact, so when you fall off your bike, there is much less force on your head. Just be glad your mom doesn’t make you wear a pillow on your head!

So let’s go back to momentum for a minute. Momentum is inertia in motion. It is how much force it takes to get something to slow down or change direction. One more concept I’d like to give you this month, is conservation of momentum. This is basically momentum equals momentum or mathematically mv=mv. (Momentum is mass times velocity.) When objects collide, the momentum that both objects have after the collision, is equal to the amount of momentum the objects had before the collision. Let’s take a look at this with this experiment.

Another Quick Momentum Experiment

1. Put one penny on the table.

2. Put another penny on the table about 6 inches away from the first one.

3. Now, slide one penny fairly fast towards the first penny.

4. What you want to have happen, is that the moving penny strikes (or gives impulse to) the stationary penny head on. The moving penny should stop and the stationary penny will move.

5. Now, try that with other coins. Make big ones hit small ones and vice versa. It’s also fun to put a line of 5 coins all touching one another. Then strike the end of the line with a moving penny.

This is conservation of momentum. If you were able to strike the penny head on, you should have seen that the penny that was moving, stopped, and the penny that was stationary moved with about the same speed of the original moving penny. Conservation of momentum is mv = mv. Once the moving penny struck the other, all the moving penny’s momentum transferred to the second penny. Since the pennies weighed the same, the v (velocity) of the first penny is transferred to the second penny and the second penny moves with the same velocity as the first penny. What happens if you use a quarter and a penny? Make the quarter strike the penny. That penny should really zip! Again mv=mv. The mass of the quarter is much greater then the mass of the penny. So for momentum to be conserved, after impact, the penny had to have a much greater velocity to compensate for its lower mass.

Mathematically it would look like this (the masses are not accurate to make the math easier to see.)

After collision Mass of Quarter x Velocity of Quarter = Mass of Penny x Velocity of Penny

5g x 10m/s = 1g x v

50 = 1 x v

50/1 = v

50m/s = v

or 5g x 10m/s = 1g x 50 m/s

50 momentum = 50 momentum

After the collision, the penny is moving at 50 m/s, 5 times faster then the quarter was moving because the penny is 5 times lighter then the quarter.

And ANOTHER Quick Momentum Experiment

Do this experiment again, but this time make the cork heavier. I wrapped mine in duct tape and then jammed a roll of electrical tape on the end. If you wanted to tape a golf ball to the cork or tape a bunch of change to it it would work as well. Just try to make the cork a good bit heavier than it was in the first place.

This is a great example of impulse as well as conservation of momentum. The impulse (Ft) is the baking soda and vinegar gas mixture creating enough pressure to force the cork off the bottle. According to Newton’s Third Law, the force from that impulse has an equal and opposite reaction, so the bus goes one way and the cork goes the other. Now take that information and combine it with what you now know about conservation of momentum. The impulse is equal for the cork and the bus, so which one is going to have more velocity due to it’s lighter mass? The cork. mv=mv. Just like the penny and the quarter, the lighter cork will go farther than the heavier bus. Now if you make the cork heavier and try it again, what will you see? Now the bus moves farther but the cork moves less far. Again, conservation of momentum, mv = mv.

Yet ANOTHER Easy Momentum Activity

1. Put the wagon and the skateboard close to one another.

2. Have one person sit on the skateboard while the other sits on the wagon.

3. Make sure the wheels are straight on the wagon and that the sidewalk is relatively free of stuff in the way.

4. Have one person give a good shove to the other person. Usually, it is easier for the person on the skateboard to push on the wagon. If this is true with your setup, then do it that way. Otherwise, do whatever is easiest.

5. Feel free to add more people or weight to the wagon and try it again.

Can you see how this and the one before it are really showing the same concept? Who went farther and faster? The lighter person on the lighter vehicle right? The impulse of the push was the same for both vehicles, so both vehicles had the same momentum. Momentum is mass and velocity so if the mass for both vehicles was the same, the speed would be the same. If the mass of one was more then the mass of the other, then the heavier one would move more slowly then the lighter one.

Highlights for Momentum & Impulse

Impulse is the amount of time a force is put on an object. How hard and how long something gets pushed or pulled.
Ft = Impulse. Impulse affects the momentum of an object.

Momentum is inertia in motion, how hard it is to get something to change directions or speed. Momentum = mv.

Conservation of momentum; mv = mv. If something hits something else the momentum of the objects before the collision will equal the momentum of the objects after the collision.

Here is another experiment in momentum: Newton’s Second Law.

Advanced students: Download your Momentum lab here.

Download Student Worksheet & Exercises

Exercises 

1. What is momentum?
2. What is impulse?
3. What is the conservation of momentum?

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Rockets shoot skyward with massive amounts of thrust, produced by chemical reaction or air pressure. Scientists create the thrust force by shoving a lot of gas (either air itself, or the gas left over from the combustion of a propellant) out small exit nozzles. This experiment and activity is for Grades 9-12.

According to the universal laws of motion, for every action, there is equal and opposite reaction. If flames shoot out of the rocket downwards, the rocket itself will soar upwards. It’s the same thing if you blow up a balloon and let it go—the air inside the balloon goes to the left, and the balloon zips off to the right (at least, initially, until the balloon neck turns into a thrust-vectored nozzle, but don’t be concerned about that just now).

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A rocket has a few parts different from an airplane. One of the main differences is the absence of wings. Rockets utilize fins, which help steer the rocket, while airplanes use wings to generate lift. Rocket fins are more like the rudder of an airplane than the wings.

Another difference is the how rockets get their speed. Airplanes generate thrust from a rotating blade, whereas rockets get their movement by squeezing down a high-energy gaseous flow and squeezing it out a tiny exit hole.

If you’ve ever used a garden hose, you already know how to make the water stream out faster by placing your thumb over the end of the hose. You’re decreasing the amount of area the water has to exit the hose, but there’s still the same amount of water flowing out, so the water compensates by increasing its velocity. This is the secret to converging rocket nozzles—squeeze the flow down and out a small exit hole to increase velocity.

There comes a point, however, when you can’t get any more speed out of the gas, no matter how much you squeeze it down. This is called “choking” the flow. When you get to this point, the gas is traveling at the speed of sound (around 700 mph, or Mach 1). Scientists found that if they gradually un-squeeze the flow in this choked state, the flow speed actually continues to increase. This is how we get rockets to move at supersonic speeds or above Mach 1.

This image (at left) is a real picture of an aircraft as it breaks the sound barrier. This aircraft is passing the speed at which sounds travel. 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. Because the aircraft is moving through air, which is a gas, the gas can compress and results in a shock wave. You can think of a shock wave as big pressure front. In this photo, the pressure is condensing water vapor in the air, hence the cloud. 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.

The rockets we’re about to build get their thrust by generating enough pressure and releasing that pressure very quickly. Here’s what you need to do:

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You’ll need to find:

• empty 2L soda bottle
• razor
• car tire valve
• bicycle pump

Modify an empty soda bottle into a rocket that launches from your hand! Important: DO NOT USE water bottles as they will burst. You MUST use a bottle that was made to hold contents under pressure.

Clamp the soda bottle cap in a vice. Using a razor blade, strip threads from the cap until you can untwist the cap completely from the bottle with one wrist movement. You’ll have to cut off approximately one full turn of threads from open end, which will make it easier to get the cap off quickly without allowing too much air pressure to leak out. It also makes this experiment more dangerous and prone to accidents as now the cap will comes off a lot easier. Be careful!

Drill a hole that matches the size of the car tire valve into the center of the cap, again using the vice to hold it still. A ½-inch spade bit works best. Next insert the valve through cap so when it’s screwed on, you can easily pressurize the bottle with a bicycle pump. To the bottle, add water , screw on the valve-cap, and pump up the pressure using the bicycle pump or air compressor until the bottle feels rock-solid.

NOTE: Bottles tend to burst above 70 psi and after extended use, so replace the bottles after 7-10 shots. As they get banged around on landing, they start forming fissures that lead to bursting under pressure. If you are using an air compressor rather than a bicycle pump, be sure to keep your air compressor set to a maximum of 70 psi.

Hold the bottle bottoms-up at an angle, grasp the cap, and begin to untwist slowly… until the water begins to drip out and leaks like a faucet. Now untwist the cap fully in one motion, and the bottle will fly a hundred feet or more, leaving you drenched and awed. Make sure you’ve got about a football field-sized launch area.

What’s happening?

This rocket uses HIGH pressure to soar skyward. Think of a balloon; when you release the end of a balloon, the air inside the balloon travels one direction and the balloon zooms in the opposite direction (initially, anyway). The Water Rocket shoots water in one direction (toward you) and launches in the other (away from you).

Why is there water in the rocket?

The water is in there to provide you with both a visual of what’s going on (when the water leaks out, you know it’s time to untwist the cap FAST), as well as giving you a time-delay to get the cap off. Try launching it without water (just pressurize the bottle) and see if you’re fast enough to launch it.

Troubleshooting: The first time kids do this experiment, they are often so surprised it works that they drop the bottle on the ground OR they grasp it so tight that they forget to let the rocket go. With practice, you will be able to launch them consistently skyward.

ALWAYS USE SAFETY GOGGLES or a FACE SHIELD!

Be sure to transport the charged bottle with the valve-side down, in case the valve tears free from the bottle.

How far did your rocket go? Tell us in the comment field! (DON’T FORGET YOUR SAFETY GOGGLES!!)
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This is a quick and easy demonstration of how to teach Newton’s laws with minimal fuss and materials. All you need is a wagon, a rock, and some friends. We’re going to do a few totally different experiments using the same materials, though, so keep up with the changes as you read through the experiment.

Remember that Newton covers a few different ideas. First, there’s the idea that objects in motion will stay going they way they’re headed, unless something gets in the way. Then there’s the resistance to motion (objects at rest tend to stay put), as well as force being proportional to how fast you can get something to move (acceleration). And lastly, there’s the idea that forces happen in pairs – if you shoot something one direction, you’re going to feel a kick in the opposite direction. Ready to see these ideas in action? Let’s go…

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Here’s what you need:

• wagon
• a rock
• friends

Part 1: Newton’s First Law (& Inertia)

Let’s really figure out what this ‘inertia’ thing from Newton’s first law is all about using the wagon and friends. Here’s what you need to do:

1. Pull the wagon down the sidewalk.

2. Try to stop as quickly as you can. Be careful. You could get run over by the wagon if you’re not careful.

3. Put a friend in the wagon and repeat steps 1 and 2.

4. Put another friend in the wagon and repeat steps 1 and 2.

5. Again…pretty easy huh?!

You may have noticed that the more friends (the more weight) you had in the wagon the harder it was to get moving and the harder it was to stop. This is inertia. The more weight something has the more inertia it has and the harder it is to get it to go and to stop!

Quiz question: Will a lighter or heaver race car with the same engine win a short-distance race (like the quarter-mile)? Tell me in the comments below what you think!

Advanced students: Download your First Law Lab here. (This is the first of TWO advanced labs!)

Download Student Worksheet & Exercises

Part 2: Newton’s Second Law

Now we’re going to experiment with Newton’s Second Law that deals with force, mass, and acceleration. Are you ready?

1. Start with an empty wagon…

2. Pull it and try to get it to go as fast as it can, as fast as you can. In other words, get it to accelerate.

3. Now add weight. Put something in the wagon that weighs at least 50 lbs. or so (a nice, solid kid comes to mind)

4. Pull it again and get it to go as fast as it can as fast as you can.

5. Add more weight and do it again.

6. Keep adding weight until you have a very difficult time getting it to accelerate.

So what happened here? Force equals mass x acceleration. The mass was the wagon. The force was you pulling. The acceleration was how fast you could get it to speed up. The heavier you got the wagon (the more mass there was) the harder (the more force) you had to pull to get the wagon to move (to accelerate).

Part 3: Newton’s Third Law

Now let’s work with Newton’s Third Law: for every action, there is an equal and opposite reaction. If this next experiment doesn’t work don’t worry about it. You need a fairly low friction skateboard or wagon to make this work, so that’s why it’s here last. You need: A skateboard or a wagon, the heaviest thing you can throw safely, and a sidewalk.

1. Sit in the wagon or on the skateboard (please do not stand up).

2. Throw the heavy thing as hard as you can. Please be careful not to hit anybody or anything.

At this point, you should know what should happen, so what do you think? If you said that the throw forward would move you backward, you’re right! Next time you’re in a small canoe, toss the rock and see what happens to you and your boat. (Any guesses?)

Advanced students: Download your Newton’s Wagon Advanced Lab here (This is the second of TWO advanced labs!)

In this next experiment, we are going to combine the concepts of Newton’s Second Law, acceleration and terminal velocity to explore Newton’s Second a little further. Are you ready?

Exercises 

1. What is inertia?
2. What is Newton’s First Law?
3. Will a lighter or heavier race car with the same engine win a short-distance race (like the quarter-mile)?
4. What concept does Newton’s Second Law of Motion deal with?
5. What is momentum?
6. What is the equation for Newton’s Second Law?
7. What is Newton’s Third law?
8. Give three examples of forces in pairs.
9. A rope is attached to a wall. You pick up the rope and pull with all you’ve got. A scientist walks by and adds a force meter to the rope and measures you’re pulling with 50 Newtons. How much force does the wall experience?
10. Can rockets travel in space if there’s nothing to push off of? Explain your answer.

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This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

We’re going to cover energy and motion by building roller coasters and catapults! Kids build a working catapult while they learn about the physics of projectile motion and storing elastic potential energy. Let’s discover the mysterious forces at work behind the thrill ride of the world’s most monstrous roller coasters, as we twist, turn, loop and corkscrew our way through g-forces, velocity, acceleration, and believe it or not, move through orbital mechanics, like satellites. We’ll also learn how to throw objects across the room in the name of science… called projectile motion. Are you ready for a fast and furious physics class?

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Materials:

• • click for worksheet
  • marbles
  • masking tape
  • 3/4″ pipe foam insulation (NOT neoprene and NOT the kind with built-in adhesive tape)
  • 9 popsicle sticks
  • 4 rubber bands
  • one plastic spoon
  • ping pong ball
  • hot glue gun with glue sticks

Key Concepts

Centripetal means ‘center-seeking’. It’s the force that points toward the center of the circle you’re moving on. When you swing the bucket around your head, the bottom of the bucket is making the water turn in a circle and not fly away. Your arm is pulling on the handle of the bucket, keeping it turning in a circle and not fly away. That’s centripetal force. Centrifugal force is equal and opposite to centripetal force. Centrifugal means ‘center-fleeing’, so it’s a force that’s in the opposite direction. The car pushing on you is the centripetal force.The push of your weight on the door is the REACTIVE centrifugal force, meaning that it’s only there when something’s happening. It’s not a real force that goes around pushing and pulling on its own.

What’s Going On?

Engines used to use an automatic feedback system called a centrifugal governor to regulate the speed. For example, if you’re mowing the lawn and you hit a dry patch with no grass, the blades don’t suddenly spin wildly faster… they get adjusted automatically by a feedback system so maintains the same speed for the blades, so matter how thick or thin the grass that your cutting is. You’ll find these also in airplanes to automatically adjust the pitch (or angle) of the propeller as it moves through the air. The pilot sets the intended speed, and the airplane has a governor that helps adjust the angle the blades make with the air to maintain this speed automatically, because the air density changes with altitude. It’s really important to know how much centrifugal force people experience, whether its in cars or roller coasters! In fact roller coaster loops used to be circular, but now they use clothoid loops instead to keep passengers happy during their ride so they don’t need nearly the acceleration that they’d need for a circular loop (which means less g-force so passengers don’t black out).

Here are more roller coaster maneuvers you can try out:

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).

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. 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).

Questions to Ask

1. Does the track change position with the weight of the marble, making it fly off course? (You can make the track more rigid by taping it to a surface.)
2. Is the marble jumping over the track wall? (You can increase your bank angle – the amount of twist the track makes along its length.)
3. How can you make your marble zip through two loops at once?
4. How could you increase your marble speed?
5. Where would you put a tunnel? (Leave one piece of track uncut to use as a tunnel.)

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Hovercraft transport people and their stuff across ice, grass, swamp, water, and land. Also known as the Air Cushioned Vehicle (ACV), these machines use air to greatly reduce the sliding friction between the bottom of the vehicle (the skirt) and the ground. This is a great example of how lubrication works – most people think of oil as the only way to reduce sliding friction, but gases work well if done right.

In this case, the readily-available air is shoved downward by the hover motor and the skirt traps the air and keeps it inside, thus lifting the vehicle slightly. The thruster motor’s job is to propel the craft forward. Most hovercraft use either two motors (one on each side) for steering, or just one with a rudder that can deflect the flow (as your project does).

The first hovercraft were thought about in the 1800s, but it wasn’t until the 1950s that real ones were first tested. Today, the military use them for patrolling hard-to-drive areas, scientists use them for swamp research studies, and businesses use them to transport toys and food across rough and icy areas. Scientists are already planning future ACVs to use magnetic levitation in addition to the air power… but it’s still on the drawing board.

Are you ready to make your own? We have TWO different models to choose from. Click this link for the Easy Balloon-Powered Model, or keep reading below for the advanced version.
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You will need:

• 1 wood skewer
• 1 wood popsicle stick
• 1 straw
• 16 oz. styrofoam cup (the kind used for sodas). Note that waxed paper cups will not work!
• 1 foam hamburger container (the one in the video is 5.5″ square and 3″ high when closed)
• 1 foam meat tray (the one in the video is approx. 10″x12″x1″ – it does not need to be these exact dimensions – try a few different sizes out to see what happens! You can get them for free if you ask for a clean one from your butcher.
• 2 3V DC motors (one smaller, one larger)
• 2  propellers (the ones in the video are 3″ diameter, so check your local hobby store and get a variety to test out) – read comments below for ideas on where to get props!
• 9V battery clip with wires
• 9V battery (get a good kind, like Duracell or Energizer)
• 9V battery holder (looks like a “C”) OR use tape to attach the battery to your hovercraft
• a couple of extra wires (speaker wire, alligator clips, etc.)
• 1 SPST switch

Download Student Worksheet & Exercises

1. First, we’ll work to make the hovercraft hover. Start by finding the center of the Styrofoam meat tray. This will be your base.
2. Use the ruler to measure the diameter of your cup to make sure it’s 3.5 inches. If it measures correctly, use the cup and pen to draw a circle in the middle of the tray
3. Carefully cut out the circle, supporting the bottom of the foam.
4. Cut your skewer into three pieces, making sure they are longer than the cut-out circle is wide.
5. Use the hot glue gun to attach the lip of the round motor onto the skewer pieces, keeping them as parallel as possible.
6. Gently attach the skewers onto the foam.
7. Attach a propeller onto the shaft of the motor which is now attached to the skewers and foam tray.
8. Now we will work with the takeout container. Open it and cut it in half and place one half to the side.
9. Check the diameter of the bottom of the foam cup to ensure it’s about 2 ¼ inches. Then you can trace it with a pen on the top of the hamburger container half.
10. Cut out the circle and discard it.
11. Using the slide switch as a guide, cut out a small rectangle in the front for the switch. Reinforce it with hot glue, being careful to NOT get hot glue in the switch. Make sure it still slides back and forth.
12. Rest the hamburger half on top – we aren’t going to attach it just yet.
13. Find the small motor and look for the small contacts (they are very small and fragile – they are copper and look a little like foil). Gently bend them up a little in the back.
14. Hot glue the motor onto the end of the popsicle stick with the shaft pointing away from the stick and the contacts pointing up.
15. Use hot glue to secure the stick across the top of the hole in the hamburger box.
16. Attach a propeller and give it a spin to make sure it will spin.
17. Find the 9-volt battery clip and hot glue the bottom of it onto the middle of the popsicle stick.
18. Cut your wire into two equal length pieces. Remove the insulation from the ends (about ¾ of an inch to an inch – get adult help if you need it). Twist the exposed wires together. Do this for both wires.
19. If you aren’t going to solder the project, you’ll need to cut off the metal ends of the 9 volt battery clip’s wires and strip the wire insulation. Twist these wires together as well.
20. Now we’ll work on wiring the inside motor. Take the end of one wire and put it halfway through one of the posts. Bend it up and twist it around itself very well to ensure it’s connected well. Do this with the other wire and connection.
21. One of these wires will go to the switch. Thread the wire through a tab and twist it around itself.
22. Attach the black wire from your 9-volt battery clip to the other tab on the switch.
23. Thread your remaining wires (the red one from the battery clip and the remaining red wire from the first, hovering motor) up through the hamburger tray to attach them to the second motor. This is the thruster motor.
24. Now that everything is wired, glue the hamburger tray to the bottom tray by placing hot glue at each of the four corners and pressing down gently.
25. To test, grab your 9-volt battery. Check to make sure everything is wired correctly – the hovercraft should hover, not be sucked down to the table, and you should feel air blowing if you hold your hand in front of the thruster motor. Switch the appropriate wires if you note any issues during testing.
26. Now we’ll build a shroud around the thruster motor. You’ll need the cup, the last piece of wooden skewer, the straw, and the remaining big piece of foam. Measure about halfway down the cup and cut it all the way around – essentially cutting it in half. You’ll be using the top of the cup – the cuff-like portion. It should fit around the propeller.
27. Starting on the cut side of the foam, cut out a rectangle to use as a shim. Hot glue the rectangle down to the hovercraft. Then hot glue the cup cuff down to the rectangle.
28. If the propeller is hitting the Styrofoam, you can move the cup around and hot glue as needed to make sure there is room for movement.
29. Make a vein from a rectangular piece of Styrofoam that fits inside the cup cuff.
30. Glue the straw onto the long end of this piece and trim the straw down. The wooden skewer should fit right through the straw.
31. Push the wooden skewer down through the top of the cup. Pierce the bottom of the cup but DO NOT pierce the bottom of the hovercraft.
32. Put the straw and Styrofoam piece in, and then thread the skewer back down through the straw.
33. Troubleshooting: make sure the bottom of the hovercraft – the tray’s lip – is as smooth as possible. You can sand it down lightly if you need to. You’ll need a clean, smooth, flat surface to hover on as well! You might also double check the motor directions. If necessary, you can lightly weigh down the front of the hovercraft to balance out the weight from the back.
34. Modification: Once the hovercraft is operational, you can hot glue foam tubing to the bottom to make a water hovercraft. However, it will no longer work on land!

Exercises:

1.  What happens if you use a larger meat tray?

2.  Add another 9V battery?

3.  se a 12VDC motor for the 3VDC motor?

4.  Remove the battery pack entirely and add longer wires so you can hold the battery in your hand as the hovercraft zooms down the hallway?

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Stand on a cookie sheet or cutting board which is placed on the floor (find a smooth floor with no carpet). Ask someone to gently push you across the floor. Notice how much friction they feel as they try to push you.

Want to make this job a bit easier?

Here’s what you need:

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• two boards (about 12″ x 12″, or whatever you have handy)
• 4-10 dowels (or round, not hexagonal, pencils)
• handful of marbles

Now place three or four dowels parallel about six inches apart between the board and the floor. Smooth wooden pencils can work in a pinch, as can the hard cardboard tubes from coat-hangers. Ask someone to push you. Is there a direction you still can’t travel easily? Now let’s add another direction to your motion…

Replace the dowels with marbles. What happens? Why do the marbles make you do in all directions? What direction(s) did the dowels roll you in?

Download Student Worksheet & Exercises

BONUS EXPERIMENT IDEA! To really drive this point home, you can make your own low-friction ball bearings: Get two cans (with a deep groove in the rim, such as paint cans) and stack them. Turn one (still on top of the other) and notice the resistance (friction) you feel. Now sandwich marbles all along the rim between the cans. Place a heavy book on top and note how easily it turns around. Oil the marbles (you can spray with cooking spray, but it is a bit messy) and it turns more easily yet.

Exercises 

1. Why do the marbles make you go in all directions?
2. What direction(s) did the dowels roll you in?

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Friction is everywhere! Imagine what the world would be like without friction! Everything you do, from catching baseballs to eating hamburgers, to putting on shoes, friction is a part of it. If you take a quick look at friction, it is quite a simple concept of two things rubbing together.

However, when you take a closer look at it, it’s really quite complex. What kind of surfaces are rubbing together? How much of the surfaces are touching? And what’s the deal with this stick and slip thing anyway? Friction is a concept that’s many scientists are spending a lot of time on. Understanding friction is very important in making engines and machines run more efficiently and safely.

Here’s what you need:

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• 2 Business card magnets (those thin flat magnets that are the size of business cards)
• Fingers

Download Student Worksheet & Exercises

1. Take two business card magnets and stick them together black side to black side. They should be together so that the pictures (or whatever’s on the magnets) are on the outside like two pieces of bread on a sandwich.

2. Now grab the sides of the magnets and drag one to the right and the other to the left so that they still are magnetically stuck together as they slide over one another.

Did you notice what happened as they slid across one another? They stuck and slipped didn’t they? This is a bit like friction. As two surfaces slide across one another, they chemically bond and then break apart. Bond and break, bond and break as they slide. The magnets magnetically “bonded” together and then broke apart as you slide them across on another. (The chemical bonds don’t work quite like the magnetic “bonds” but it gives a decent model of what’s happening.) There are many mysteries and discoveries to be uncovered with this concept. Go out and make some!

Exercises 

1. What is the difference between static and kinetic friction? Which one is always greater?
2. Design an experiment where you can observe and/or measure the difference between static and kinetic friction.

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Now let’s talk about the other ever present force on this Earth, and that’s friction. Friction is the force between one object rubbing against another object. Friction is what makes things slow down.

Without friction things would just keep moving unless they hit something else. Without friction, you would not be able to walk. Your feet would have nothing to push against and they would just slide backward all the time like you’re doing the moon walk.

Friction is a very complicated interaction between pressure and the type of materials that are touching one another. Let’s do a couple of experiments to get the hang of what friction is.
Here’s what you need:

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• About 5 different shoes
• A board, or a tray, or a large book at least 15 inches long and no more then 2 feet long.
• A ruler
• Paper
• Pencil
• A partner

Download Student Worksheet & Exercises

1. Put the board (or whatever you’re using) on the table.

2. Put the shoe on the board with the back of the shoe touching the back of the board.

3. Have a partner hold the ruler upright (so that the12 inches end is up and the 1 inch end is on the table) at the back of the board.

4. Slowly lift the back of the board leaving the front of the board on the table. (You’re making a ramp with the board). Eventually the shoe will begin to slide.

5. Stop moving the board when the shoe slides and measure the height that the back of the board was lifted to.

6. Look at the 5 shoes you chose and test them. Before you do, make a hypothesis for which shoe will have the most friction. Make a hypothesis. On a scale from 1 to 5 (or however many shoes you’re using) rate the shoes you picked. 1 is low friction and 5 would be high friction. Write the hypothesis next to a description of the shoes on a piece of paper. The greater the friction the higher the ramp has to be lifted. Test all of the shoes.

7. Analyze the shoes. Do the shoes with the most friction show any similarities? Are the bottoms made out of the same type of material? What about the shoes with very little friction?

Any surprises with which shoe had the most or least friction? Compare the shoe with the most friction and the shoe with the least friction. Do you notice anything? Usually, the shoe that has the most friction has more shoe surface touching the board then most of the other shoes.

Also, often the shoe with the least friction, has the least amount of shoe touching the board. Since friction is all about two things rubbing together, the more surface that’s rubbing, the more friction you get. A tire on you car should have treads but a race car tire will be absolutely flat with no treads at all. Why?

The race car doesn’t have to worry about rain or wetness so it wants every single bit of the tire to be touching the surface of the track. That way, there is as much friction as possible between the tire and the track. The tire on your car has treads to cut through mud and water to get to the nice firm road underneath. The treads actually give you less friction on a flat dry road!

Some of you might have used a skateboard shoe for your experiment. Notice, that the skateboard shoe has quite a flat bottom compared to most other shoes. This is because a skateboarder wants as much of his or her shoe to touch the board at all times.

Exercises 

1. What is friction?
2. What is static friction?
3. What is kinetic friction?

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You have just taken in a nice bunch of information about the wild world of gravity. This next section is for advanced students, who want to go even deeper. There’s a lot of great stuff here but there’s a lot of math as well. If you’re not a math person, feel free to pass this up. You’ll still have a nice understanding of the concept. However, I’d recommend giving it a try. There are some fun things to do and if you’re not careful, you might just end up enjoying it!

Here’s what you need:

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• ball
• pencil, paper
• stopwatch
• yardstick or tape measure

Download Student Worksheet & Exercises

Okay, let’s see where we can go here. Gravity accelerates all things equally…what does that mean? All things accelerate at 32 feet per second squared due to gravity. In metric, it accelerates 9.8 meters per second squared.

What that means is, every second something falls, its speed increases by 32 feet/second or 9.8 meters/second. Believe it or not, that’s about 22 miles per hour!! Gravity will accelerate something from 0 to 60 mph in about 3 seconds. Faster then all but the fastest sports cars!

So what is acceleration anyway? Well speed is the amount of distance something travels in a certain amount of time. Five miles per hour, for example, tells you that something can travel five miles in an hour. Acceleration is how much the speed changes over time. So acceleration would be miles per hour per hour or feet per second per second.

Acceleration is a rate of change of speed or, in other words, how fast is the speed is changing. Feet per second per second is the same as ft/s/s which is the same as ft/s². (I told you we were going deeper!) Let’s say you’re riding your bicycle at a positive acceleration (your getting faster) of 5 ft/s².

That means in 1 second you’re moving at a speed of 5 ft/s.

After 2 seconds you’re moving at a speed of 10 ft/s.

After 3 seconds you’re now clipping along at 15 ft/s (about 10 mph).

So you can see that as long as you accelerate, you will be getting faster and faster. The formula for this is v=at where v is velocity, a is acceleration and t is time. (We will be doing more with acceleration in a future lesson.)

If we want to find out how fast something is going after it has been dropped, we use the formula v=gt. The letter “v” stands for velocity (which basically means speed.) “g” stands for the gravitational constant and “t” stands for time.

If we want to find out how fast a golf ball is dropping after it falls for 3 seconds we multiply 3 seconds by 32 feet/second squared and that equals 96 feet/second. So, if I dropped a golf ball off a building, it would be going 96 feet per second after 3 seconds of dropping.

The formula looks like this when we fill in the numbers:

v=3s x 32 ft/s²

If we do more math, we’ll see that after one second something will be item7going 32 ft/s, after 2 seconds it will be going 64 ft/s, after 3 seconds 96 ft/s after 4 seconds 128 ft/s. Get it? Anything dropped will be going that speed after that many seconds because gravity accelerates all things equally (air resistance will effect these numbers so you won’t get exactly the numbers in practice that you will mathematically).

All right, lets go even deeper. We now know how to calculate how fast something will be going if it is dropped, but what happens if we throw it up? Well, which way does gravity go? Down right? Gravity accelerates all things equally so, gravity will slow things down as they travel up by 32 ft/s². If a ball is thrown up at 64 ft/s how long will it travel upwards? Well, since it is negatively accelerating (in physics there’s no such thing as deceleration) after the first second the ball will be traveling at 32 ft/s and after 2 seconds the ball will come to a stop, turn around in midair, and begin to accelerate downwards at 32 ft/s². Using this, you can tell how fast you can throw by using nothing more then a timer. Let’s try it.

For this experiment, you will need:

– A ball (a tennis ball or baseball would be perfect)

– A stopwatch

– Pencil and paper

– A friend

– A calculator

1. Go outside and pick one person to be the thrower and another to be the timer.
2. Have the timer say “Ready, Set, Go!” and at go he or she should start the stopwatch.
3. When the timer says go, the thrower should toss the ball as high as he or she can.
4. The timer should stop the stopwatch when the ball hits the ground.
5. Write down the time that the ball was in the air.
6. Let each person take a couple of turns as timer and thrower.
7. Now, come back inside and do a bit of math.

Ok, let’s see how you did. Let’s say you threw the ball into the air and it took 3 seconds to hit the ground. The first thing you have to do is divide 3 in half. Why? Because your ball traveled 1.5 seconds up and 1.5 seconds down! (By the way, this isn’t completely accurate because of two things. One, air resistance and two, the ball falls a little father then it rises because of the height of the thrower.) Now, take your formula and figure out the speed of the throw.

v=gt,

so v=32 ft/s² x 1.5 sec or

v = 48 ft/s.

So, if that’s how fast it left your hand…how fast was it going when it hit the ground? Yup, 48 ft/s. It has to be going the same speed because it had just as much time to speed up as it had to slow down, 1.5 seconds. Try that with your time and see how fast your throw was.

Ok, hold your breath, just a little deeper now. Let’s talk about distance. If something starts from rest you can tell how far it drops by how long it has dropped. This formula is d=1/2gt² or distance equals one half the gravitational constant multiplied by time squared. Let’s try it. If I drop a ball and it drops 3 seconds how far has it dropped?

d=1/2 32ft/s² x (3s)² or

d = 16 ft/s x 9s² or

d=144 ft So it has dropped 144 ft.

Now try this with your time. What’s the first thing you have to do? Divide your time in half again, right. It took your ball half the time to go up and half the time to come down. Now plug your numbers into 1/2gt² and find out how high you threw your ball! Is Major League Baseball in your future?!

Advanced students: Download your Fast Ball Lab here.

Exercises 

1. Is gravity a speed, velocity, or acceleration?
2. Does gravity pull equally on all things?
3. Does gravity accelerate all objects equally?
4. How is acceleration different from speed and velocity?

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This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

Blast your imagination with this super-popular class on rocketry! Kids learn about fin design, hybrid and solid-state rocketry, and how rockets make it into space without falling out of orbit. This class is taught by a real live rocket scientist (me!). We’ll launch rockets during the class, too!

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Materials:

• straw
• paperclip
• rubber band
• index card
• popsicle stick
• scissors
• masking tape
• water
• alka-seltzer tablets (generic brands work fine)
• film canister or small container with tight-fitting lid
• OPTIONAL: Small toy car

Below you will find an older version of the same teleclass. We are making a different experiment during class, so the materials you will need are a little different:

Materials:

• 2L soda bottle
• 1/2″ PVC pipe
• duct tape
• pen or pencil
• index cards
• sheets of paper
• bicycle inner tube

Key Concepts

A rocket has a few parts different from an airplane. One of the main differences is the absence of wings. Rockets utilize fins, which help steer the rocket, while airplanes use wings to generate lift. Rocket fins are more like the rudder of an airplane than the wings.

Another difference is the how rockets get their speed. Airplanes generate thrust from a rotating blade, whereas rockets get their movement by squeezing down a high-energy gaseous flow and squeezing it out a tiny exit hole. If you’ve ever used a garden hose, you already know how to make the water stream out faster by placing your thumb over the end of the hose. You’re decreasing the amount of area the water has to exit the hose, but there’s still the same amount of water flowing out, so the water compensates by increasing its velocity. This is the secret to rocket nozzles – squeeze the flow down and out a small exit hole to increase velocity.

The rockets we’re about to build get their thrust by generating enough pressure and releasing that pressure very quickly. You will generate pressure both by pumping and by chemical reaction, which generates gaseous products.

What’s Going On?

For every action, there is equal and opposite reaction. If flames shoot out of the rocket downwards, the rocket itself will soar upwards. It’s the same thing if you blow up a balloon and let it go-the air inside the balloon goes to the left, and the balloon zips off to the right (at least, initially).

Your rocket generates a high pressure by squeezing the air into a very small space and using Bernoulli’s Principles in action! As you stomp on the rocket, the air pressure leaves the bottle pretty quickly, pushing the paper rocket out of the way as it zooms out of the tube. By narrowing the exit diameter, you allow the air to speed up as it exits, creating a higher launch for your rocket.

You can modify your rocket body design. Add more fins, tilt the fins at a angle, or try no fins at all! You can add a more steeply slanted  nose. You can cut the rocket body in half or make it twice as long.  There’s so many things you can test out, change, or modify with this simple activity! You can also add canards (glider-type wings) to either side of the rocket body right under the nose and turn it into a glider when it starts to fall back to Earth!

Questions to Ask

1. Does it matter how many fins you use?
2. What happens if there’s an air leak in the system?
3. How can you make the rocket fly even higher? Name three different ways.
4. Is the center of pressure before or aft of the center of gravity on your rocket?
5. For stable flight, how many fins do you ideally need?
6. How can you make the rocket spin as it launches?

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This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

Soar, zoom, fly, twirl, and gyrate with these amazing hands-on classes which investigate the world of flight. Students created flying contraptions from paper airplanes and hangliders to kites! Topics we will cover include: air pressure, flight dynamics, and Bernoulli’s principle.

Materials:

• 5 sheets of 8.5×11” paper
• 2 index cards
• 2 straws
• 2 small paper clips
• Scissors, tape
• Optional: ping pong ball and a small funnel

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Key Concepts

While the kids are playing with the experiments see if you can get them to notice these important ideas. When they can explain these concepts back to you (in their own words or with demonstrations), you’ll know that they’ve mastered the lesson.

1. Air pressure is all around us. Air pushes downward and creates pressure on all things.
2. Air pressure changes all the time.
3. Higher pressure always pushes.
4. The faster air travels over a surface, the less time it has to push down on that surface and create pressure. Fast moving air creates low pressure regions. (Bernoulli’s Law).
5. The four fundamental forces on an airplane are lift, weight, thrust, and drag.

What’s Going On?

There’s air surrounding us everywhere, all at the same pressure of 14.7 pounds per square inch (psi). You feel the same force on your skin whether you’re on the ceiling or the floor, under the bed or in the shower.

An interesting thing happens when you change a pocket of air pressure – things start to move. This difference in pressure causes movement that creates winds, tornadoes, airplanes to fly, and some of the experiments we’re about to do together.

An important thing to remember is that higher pressure always pushes stuff around. While lower pressure does not “pull,” we think of higher pressure as a “push”. The higher pressure inside a balloon pushes outward and keeps the balloon in a round shape.

Weird stuff happens with fast-moving air particles. When air moves quickly, it doesn’t have time to push on a nearby surface, such as an airplane wing. The air just zooms by, barely having time to touch the surface, so not much air weight gets put on the surface. Less weight means less force on the area. You can think of “pressure” as force on a given area or surface. Therefore, a less or lower pressure region occurs wherever there is fast air movement.

There’s a reason airplane wings are rounded on top and flat on the bottom. The rounded top wing surface makes the air rush by faster than if it were flat. When you put your thumb over the end of a gardening hose, the water comes out faster when you decrease the size of the opening. The same thing happens to the air above the wing: the wind rushing by the wing has less space now that the wing is curved, so it zips over the wing faster, and creates a lower pressure area than the air at the bottom of the wing.

The Wright brothers figured how to keep an airplane stable in flight by trying out a new idea, watching it carefully, and changing only one thing at a time to improve it. One of their biggest problems was finding a method for generating enough speed to get off the ground. They also took an airfoil (a fancy word for “airplane wing”), turned it sideways, and rotated it around quickly to produce the first real propeller that could generate an efficient amount of thrust to fly an aircraft.  Before the Wright brothers perfected the airfoil, people had been using the same “screw” design created by Archimedes in 250 BC.  This twist in the propeller was such a superior design that modern propellers are only 5% more efficient than those created a hundred years ago by the two brilliant Wright brothers.

Questions to Ask

When you’ve worked through most of the experiments ask your kids these questions and see how they do:

1. Higher pressure does which? (a) pushes (b) pulls (c) decreases temperature (d) meows (e) causes winds, storms, and airplanes to fly
2. The tips on the edge of a paper airplane wing provide more lift by: (a) flapping a lot
   (b) destroying wingtip vortices that kill lift (c) getting stuck in a tree more easily (d) decreasing speed
3. In the ping pong ball and funnel experiment, the ball stayed in the funnel was because:         (a) you couldn’t blow hard enough (b) you glued it into the funnel (c) the ball had a hole in it  (d) the fast blowing caused a low-pressure region around the ball, causing the surrounding atmospheric pressure to be a higher pressure, thus pushing the ball into the funnel
4. If your plane takes a nose dive, you should try (a) changing the elevators by pinching the edges (b) change the dihedral angle (c) change how you throw it (d) all of the above
5. What are the four forces that act on every airplane in flight?
6. Draw a quick sketch of your plane viewed from the front with a positive dihedral.
7. If you were designing your own “Flying Paper Machine Kit”, what would be inside the box?
8. What’s the one thing you need to remember about higher pressure?
9. What keep an airplane from falling?
10. Where is the low pressure area on an airplane wing?

Answers:

1 (a, e) 2 (b) 3 (d) 4 (d) 5 (lift, weight, thrust, drag) 8 (higher pressure pushes) 9 (lift) 10 (top surface)

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This roof can support over 400 times its own weight, and you don’t need tape! One of the great things about net forces is that although the objects can be under tremendous force, nothing moves! For every push, there’s an equal and opposite pull (or set of pulls) that cancel each other out.

This barrel roof is an excellent example of how to the forces all cancel out and the roof stands strong (hopefully!) If you have trouble with this experiment, just use cardstock or other heavy weight paper instead of regular copy paper.

Here’s what you need:
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• Print out this template.
• Scissors
• 2 pencils
• Thread
• Flat book or light clipboard
• Extra paper to load the roof

Watch the video:

Download Student Worksheet & Exercises

Exercises 

1. What is Newton’s Third Law?
2. What kind of groups do forces come in?
3. What is another name for Newton’s Third Law?

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What keeps building from toppling over in the wind? Why are some earthquake-proof and others not? We’re going to look at how engineers design buildings and bridges while making our own.

Here’s what you need:
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• Index cards
• Blocks
• Straws
• Clay
• Disposable cups

Watch the video:

Download Student Worksheet Exercises

Exercises 

1. What are three different kinds of forces?
2.  Using only blocks, what kind of wall design is the weakest?
3.  Why does the bridge seem stronger when a card is arched underneath?

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This experiment is for advanced students.

Who gets to burn something today? YOU get to burn something today!

You will be working with Zinc (Zn). Other labs in this kit allow us to burn metal, but there is a bit of a twist this time. We will be burning a powder.

Why a powder instead of a solid ribbon or foil as in the other labs?  Have you heard of surface area being a factor in a chemical reaction? The more surface area there is to burn, the more dramatic the chemical change. So, with this fact in mind, a powder should burn faster or be more likely to burn than a large solid.

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Zinc (Zn) is a metallic element. It is element #30 on the periodic table. Chemically, it is similar to magnesium, another element that we use in our experiments.

Brass is an alloy of zinc and copper. Brass has been an important metal since the 10^th century B.C. Alchemists in the dark ages burned zinc in air, just like we will do, to make what they called “white snow”. Their “white snow is our zinc oxide.

Zinc is an important element in our lives. Zinc deficiency causes lack of proper growth, delayed physical maturation, and susceptibility to infection. Zinc deficiency contributes to the death of 800,000 children per year. Excess zinc in our bodies can cause problems for us as well.

Materials:

• Alcohol burner
• Lighter
• Measuring spoon
• Zinc powder (MSDS)
• Porcelain tile work surface

Remember to dispose of your zinc oxide in the outside trash, and conduct your experiment in a well ventilated area. Fumes from this experiment are irritating and a little dangerous.

C3000: Experiment 53

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Zinc powder will burn in the presence of oxygen, producing interesting colors. The flame from burning zinc is blue, as the zinc undergoes a chemical change to become zinc oxide. Zinc oxide is thermochromic. That means that it changes colors depending on the temperature. When cool, ZnO is white. When heated, zinc oxide turns yellow, and as it cools, returns to become a white powder again. The color changes are caused by a small loss of oxygen at high temperatures, and a small gain of oxygen as it cools in air.

2Zn + O₂ –> 2ZnO

Zinc powder burned in air reacts with the oxygen and turns into zinc oxide. Zinc oxide is used in sunscreen and to treat burns, cuts, and diaper rash.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals and cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage.

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What state of matter is fire? Is it a liquid? I get that question a LOT, so let me clarify. The ancient scientists (Greek, Chinese… you name it) thought fire was a fundamental element. Earth, Air Water, and Fire (sometimes Space was added, and the Chinese actually omitted Air and substituted Wood and Metal instead) were thought to be the basic building blocks of everything, and named it an element. And it’s not a bad start, especially if you don’t have a microscope or access to the internet.

Today’s definition of an element comes from peeking inside the nucleus of an atom and counting up the protons. In a flame, there are lots of different molecules from NO, NO₂, NO₃, CO, CO₂, O₂, C… to name a few. So fire can’t be an element, because it’s made up of other elements. So, what is it?

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Fire is a combination of different gases and hot plasma. It’s a complicated exothermic (gives off heat) chemical reaction that releases a lot of heat and light (you can feel and see the flame). You need three things for a flame: oxygen, fuel, and a spark. When you take away one of these three, you snuff the flame and stop the chemical reaction. You start with fuel (usually contains carbon), and add oxygen to get carbon dioxide, carbon monoxide, nitric oxide, and many other gases and leftover ash. Most flames are hot enough to heat the gas mixture to create tiny bits of plasma within the flame, so fire is actually involved in two states of matter.

In this experiment, we’re going to see how you can protect a surface from burning using water. Are you ready?

Materials:

• Shallow baking dish
• Tongs
• Rubbing Isopropyl Alcohol (50-91%)
• Water (omit if using 50-70% alcohol)
• Dollar bill
• Fire extinguisher
• Adult help

Download Student Worksheet & Exercises

What’s going on? Alcohol burns with a slightly blue and orange flame (as shown in the video). The secret to keeping the dollar bill from burning is the water you mixed in with the alcohol. Water has a high heat capacity, which means that the water absorbs the energy from the flame and keep the bill from catching on fire. If you dipped the dollar bill in pure 100% alcohol, the temperature would rise high enough on the bill to burn. The reason we chose a bill instead of regular paper is that the dollar bill is a combination of linen and paper, making it much stronger and absorbent for this experiment.

You need both the water and the alcohol for this experiment. The water, as it absorbs the energy from the flame, heats up to its boiling point and then vaporizes, keeping the bill cool enough to not catch on fire. The alcohol is the fuel needed to keep the flame going. It’s a delicate balance between the two, but here are a couple of variations you can try out:

• You can change the color of the flame by adding in a sprinkling of salt (for yellow), boric acid (for green), or epsom salt (for white).

• You can also try mixing different ratios of water to alcohol, using 50%, 70% and 91% isopropyl alcohol. You can also try ethyl alcohol (which is an entirely different molecule) but will react about the same with this experiment. Note that if you decrease the water content too much, you’re going to lose your dollar bill.

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No kidding! You’ll be able to show your friends this super-cool magic show chemistry trick with very little fuss (once you get the hang of it). This experiment is for advanced students. Before we start, here are a few notes about the setup to keep you safe and your nasal passages intact:

The chemicals required for this experiment are toxic! This is not an experiment to do with little kids or pets around, and you want to do the entire experiment outside or next to an open window for good ventilation, as the fumes from the sodium hydroxide/zinc solution should not be inhaled.

This experiment is not dangerous when you follow the steps I’ve outlined carefully. I’ll take you step by step and show you how to handle the chemicals, mix them properly, and dispose of the waste when you’re done.

Goggles and gloves are a MUST for this experiment, as the sodium hydroxide (in both liquid and solid form) is caustic and corrosive and will burn your skin on contact.

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Is it REAL gold?

No. But it’s very close in color, as is the ‘silver’. The basic idea behind the experiment is this: by cleaning the pennies in the first step, you clear off any oxide layers to expose the copper surface. When you dip it in the solution, a galvanization reaction starts (just like ‘galvanized nails’) covering the penny with a metallic silver zinc coating.

The torching process fuses the zinc and the copper together to make the gold colored brass coating. Be careful, though, as brass has a low melting temperature and if you leave it in the flame too long, you’ll burn off the brass coating.

Materials:

• propane torch with adult help
• shiny copper pennies
• distilled white vinegar
• Pyrex glass beaker
• sodium hydroxide (solid)
• zinc powder (dust)
• alcohol burner
• stand that fits over the alcohol burner
• lighter with adult help
• wire mesh screen
• popsicle sticks
• water
• salt
• disposable cup
• gloves
• goggles
• tweezers or pliers

Download Student Worksheet & Exercises

The chemical reaction plates the copper on the penny with zinc (called galvanization). The zinc reacts with the hot sodium hydroxide solution to form soluble sodium zincate (Na₂ZnO₂), which is converted to metallic zinc when it hits the surface of the penny.

Heating the penny fuses the zinc and copper together to form an alloy called brass. The amounts of copper and zinc in brass can vary a lot, from 60-82% copper and 18-40% zinc.

DISPOSAL INSTRUCTIONS: If you simply wipe out the beaker with a paper towel and toss it in the trash, you run the risk of igniting your trash can because the combination of sodium hydroxide and zinc is very exothermic (lots of heat is generated).

Make sure to use plenty of water to remove the sodium hydroxide first before removing the metal. Sodium hydroxide will not harm the plumbing in the sink as it is also used as a drain cleaner (dissolves hair, etc.) but don’t get it on your hands!  Vinegar will neutralize any residual sodium hydroxide.

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This experiment is for advanced students.

Ever use soap? Sodium hydroxide (NaOH) is the main component in lye soap. NaOH is mixed with some type of fat (vegetable, pig, cow, etc). Scent can be added for the ‘pretty’ factor and pumice or sand can be added for the manly “You’re coming off my hands and I’ll take no guff” factor. Lots of people still make their own soap and they enjoy doing it.

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One of the coolest uses for sodium hydroxide is in tissue digestion. By “tissue” we mean meat, bone, sinew…..meaning bodies! People who pick up dead animal (road kills) for the county dump their catch in barrels containing sodium hydroxide. The NaOH eats everything up and then the “sludge” is dumped in the landfill. They used NaOH to make them decompose. So this stuff is nasty and should never be touched with your bare hands!!

Materials:

• Erlenmeyer flask
• Alcohol burner
• Lighter
• Heating rod
• Sodium carbonate (Na₂CO₃) (MSDS)
• Calcium hydroxide (Ca(OH)₂) (MSDS)
• Measuring spoon
• Water
• Tripod stand
• Wire screen
• Chemistry stand
• Test tube holder
• Test tube rack
• Test tube
• Filter paper
• Funnel
• Stock bottle for NaOH storage (MSDS)

Don’t inhale any fumes from reactions or powder welling out of chemical containers, especially calcium hydroxide dust. We want to test our product to see if it is NaOH. It should turn red litmus blue.

We will perform a bunch of operations in this lab.

1. Heating our calcium hydroxide / sodium carbonate mixture to create calcium carbonate and sodium hydroxide.
2. Filter out the calcium carbonate to collect the sodium hydroxide.
3. Test our sodium hydroxide product for the properties of NaOH.

C3000: Experiments

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Ca (OH)₂ + Na₂CO₃ –> 2NaOH + CaCO₃

Calcium hydroxide and sodium carbonate are combined in water and heated to produce sodium hydroxide and calcium carbonate

This is a double replacement reaction because the calcium ion and the sodium ion have swapped places

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids must be neutralized with vinegar, if a base, or baking soda, if an acid, before washing them down the drain. Before actually washing them down the drain check again with litmus paper to ensure that they have been neutralized. Solids are thrown in the trash.

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In this lab, we’re going to investigate the wonders of electrochemistry. Electrochemistry became a new branch of chemistry in 1832, founded by Michael Faraday. Michael Faraday is considered the “father of electrochemistry”. The knowledge gained from his work has filtered down to this lab. YOU will be like Michael Faraday. I imagined he would have been overjoyed to do this lab and see the results. You are soooo lucky to be able to take an active part in this experiment. Here’s what you’re going to do…

You will be “creating” metallic copper from a solution of copper sulfate and water, and depositing it on a negative electrode. Copper is one of our more interesting elements. Copper is a metal, and element 29 on your periodic table. It conducts heat and electricity very well.

Many things around you are made of copper. Copper wire is used in electrical wiring. It has been used for centuries in the form of pipes to distribute water and other fluids in homes and in industry. The Statue of Liberty is a wonderful example of how beautiful 180,000 pounds of copper can be. Yes, it is made of copper, and no, it doesn’t look like a penny…..on the surface. The green color is copper oxide, which forms on the surface of copper exposed to air and water. The oxide is formed on the surface and does not attack the bulk of the copper. You could say that copper oxide protects the copper.

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Our bodies use copper to our advantage, but in a proper form that is not toxic. Too much copper will make you sick and could kill you. Remember…don’t eat your chemistry set!

Materials:

• Carbon rod (MSDS)
• Copper sulfate (CuSo₄) (MSDS)
• Aluminum foil
• 9V battery with clip
• 2 wires
• Disposable cup
• Water

You are going to make a saturated solution of copper sulfate (CuSO₄) in water. Pour a measuring spoon of granulated copper sulfate in the measuring cup of water. Stir well. Continue adding a spoonful and stirring until no more crystals will go into solution. The solution is saturated when no more crystals will dissolve and there are undissolved crystals at the bottom of the container.

C1000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

CuSO₄ + H₂O (Copper sulfate is added to water)

CuSO₄ + H₂O –> Cu²⁺ + SO₄^2- (Copper sulfate plus water yields positively charged carbon ion and negatively charged sulfate ion)

When mixed with water, copper sulfate dissociates into copper and sulfate ions. Notice that the ions, now separated, take on negative and positive charges.

Next, 9V of electricity is passed through the solution with an electrode of carbon and an electrode of aluminum foil inserted into the solution. As electricity flows from one electrode to another, the copper ions, being positively charged, are attracted to the negative electrode. You can confirm this in two ways. One, if litmus paper, held close to an electrode, turns blue, that is the negative electrode. The other way is to just follow the negative lead from the battery to the negative electrode.

As the process moves along, the negative electrode gains copper ions. Evidence of this is seen on the surface of the electrode.

Here’s the breakdown of the entire process:

When the copper sulfate (CuSO4) mixed with water (H2O), the copper sulfate dissociated:

CuSO₄ –> Cu²⁺ + SO₄^2-

When power is added to the solution, the copper ions move toward the negative cathode (carbon rod) and take electrons from it, forming solid copper right on the electrode:

Cu²⁺+ 2e^– –> Cu_(s)

On the positive anode (the aluminum foil), you’ll see bubbles instead of a solid forming. The anode attracted electrons from the water molecule to form oxygen bubbles:

6H₂O –> O₂ + 4H₃O⁺ + 4e^–

Let’s put these two reactions together to get the overall reaction of:

2Cu²⁺ + 6H₂O –> 2Cu + O₂ + 4H₃O⁺

Note the difference between galvanic cells and electrolytic cells: galvanic use spontaneous chemical reactions (like in a car battery) to generate electricity, and electrolytic cells use electricity to make the chemical reaction to occur and move electrons to move in a way they would go on their own (like in this experiment).

Clean up: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. Rinse three times, wash with soap, rinse three times.

Wipe off the carbon rod to remove the copper. The aluminum goes in the trash, but the solution and solids at the bottom cannot. The liquid contains copper, a toxic heavy metal that needs proper disposal and safety precautions. Another chemical reaction needs to be performed to remove the heavy metal from the copper sulfate. Add a thumb sized piece of steel wool to the solution. The chemical reaction will pull out the copper out of the solution. The liquid can be washed down the drain. The solids cannot be washed down the drain, but they can be put in the trash. Use a little water to rinse the container free of the solids.

Place all chemicals, cleaned tools, and glassware in their respective storage places.

Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

Going Further

Here is a link to information about making your own geode (crystal lined rock) of copper sulfate crystals:

http://chemistry.about.com/od/growingcrystals/ht/geode.htm

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If we don’t have salt, we die. It’s that simple. The chemical formula for salt is NaCl. Broken down, we have Na (sodium) and Cl (chlorine). Either one of these can be fatal in sufficient quantities. When chemically combined, these two deadly elements become table salt. What once could kill now keeps us alive. Isn’t chemistry awesome?

Chlorine, element 17, is called a halogen as are all the elements in the 17^th row. All halogens have similar chemical properties. They are highly reactive nonmetals, and react easily with most metals. Sodium is a metal, and is bonded with sodium in the table salt used in this lab. Besides being found in salt, chlorine has many uses in our world such as killing bacteria in our water, making plastic, cleaning products, and the list goes on. A very useful chemical, and is among the top ten chemicals produced in the United States. Ever since its discovery in 1774, chlorine has been very useful. It is found in nature in sodium chloride, but in very small concentrations. Seawater, the most abundant source of chlorine, has a concentration of only 19g of chlorine per liter.

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Although chlorine is abundant in nature (about 2% of the mass of the ocean is chloride ions), scientists have developed a safe way to make chlorine. Chlorine has been manufactured for a hundred years through different processes: Membrane Cell, Diaphragm Cell, and Mercury Cell processes. In the first two processes, salt water (NaCl + H₂O) and caustic soda (NaOH) are used along with a power supply to generate chlorine and hydrogen gas.

Molecules that contain chlorine that find their way into the upper atmosphere can destroy the ozone layer. The ozone-oxygen cycle is a chemical process that transforms the harmful UV light (240-310nm) from the sun into heat. The oxygen and ozone molecules are constantly being switched back and forth as the sun’s UV breaks down the ozone and the oxygen molecules reacts with other oxygen atoms.

This reaction converts UV radiation into thermal energy which heats up the atmosphere (this reaction happens slowly):

O₃ –> O₂ + O

If two free oxygen atoms meet, they form a new oxygen molecule:

2O –> O₂

If this new molecule meets another free oxygen, it creates another ozone molecule:

O₂ + O –> O₃

If an ozone and an oxygen molecule meet, they form two oxygen, and this process removes ozone from the atmosphere. This process is very slow, however, so the naturally occurring reaction of:

O₃ + O –> 2O₂

is nothing to worry about. It’s when this reaction gets sped up by catalysts that we have to pay close attention. There are many catalysts that can speed up the removal of ozone, such as chlorine, bromine, and nitric oxide (NO₃). And since they are catalysts in the reaction (meaning they simply speed up the reaction without getting used), they can do this over and over again before they move out of the atmosphere completely. One chlorine atom can speed up (catalyze) tens of thousands of ozone removal reactions before it moves out of the stratosphere. Scary, huh?

CFCs (chlorofluorocarbons) such as aerosols, refrigerants (R-12), and solvents have been banned because of their damaging effect on the atmosphere. When sunlight hits a CFC, it splits off a chlorine ion:

CCl₃F –> CCl₂F^– + Cl^–

This free chlorine ion catalyzes the ozone into oxygen:

O₃ + O^– + Cl^– –> 2 O_{2 +} Cl^–

The chlorine we’re going to generate in our experiment is a minuscule amount. Even so, it is still a good idea to perform this experiment in an area with good ventilation or outdoors.

Remember to wear your gloves and goggles. True, the amount of chlorine produced is small and pretty harmless. But there are several factors that make it prudent to wear your protection. Not everyone has the same sensitivity to chemicals. Even in this lab, a person could get their skin irritated to some degree. Eyes are very sensitive organs, and I know I don’t want any amount of chlorine contacting my eyes.

Here’s what you’re going to need to do this experiment:

Materials:

• 9V battery clip
• carbon rod
• wires
• disposable cup
• salt
• water
• aluminum foil
• gloves, goggles

We will be observing a decomposition reaction. A decomposition reaction separates a substance into two or more substances that may differ from each other and from the original substance.

ZcQr –> Zc + Qr

When separated, the free elements to the right of the equation become ions, one positively charged and one negatively charged.

A very important concept to learn in this lab is that charged particles (ions) will move toward either a positive or negative electrode. The ions that move toward the anode (positive terminal) are anions, and the ones that move toward the cathode (negative) are cations.

Decomposition of any kind is the breaking down of the whole into smaller parts that were once part of the whole.

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

An electrical charge is passing through a saturated solution of salt (NaCl). It will sit there and just be salt unless that electrical charge is imposed on it. The electrical charge excites the molecules, and causes the molecules of salt to decompose, to pull apart, to break into simpler parts. These ions are negatively and positively charged. Negatively charges particles have more electrons than protons and seek a balance. In order to have an electric current, you need to have positive and negative electrodes. Opposites attract, so the negative ions move to the positive electrode and the positive ions are attracted to the negative electrode.

NaCl –> Na⁺ + Cl^–

Sodium chloride decomposes into sodium and chlorine ions.

The anode (positive, carbon rod) soaks up free electrons, which get pumped to the cathode (negative, aluminum foil) and released into the solution. If you press litmus paper against the aluminum strip, you’ll find it’s blue (basic), and red when pressed to the anode (carbon rod). The bubbles on the carbon rod are made of chlorine. The chlorine ions in the solution are attracted to the positive pole (carbon rod) and quickly combine to form chlorine gas:

2Cl^– –> Cl₂

The sodium ions move toward the aluminum foil and split the water molecule into ions:

H₂O –> H⁺ + OH^–

The hydrogen ions are converted into hydrogen gas:

2H⁺ –> H₂

The sodium ions (Na+) that remain in the solution combine with the OH- ions to create sodium hydroxide which turns the litmus paper blue:

Na⁺ + OH^– –> NaOH

The main concept I want you to understand with this experiment is that charged particles (ions) will move toward either a positive or negative electrode. The ions that move toward the anode (positive terminal) are anions, and the ones that move toward the cathode (negative) are cations.

Before you dispose of the solution, try this variation on the experiment: remove the foil and hold a salt-water filled test tube (filled to the top with salt water and capped with a gloved thumb and submerged into the solution). Place the cathode wire into the tube and you’ll see bubbles rising up into the tube. What type of gas is it? (Hint: wait until the tube is nearly full before removing it and using a match to test.)

For C3000 Students: Use this experiment as the basis for Experiment 123.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Magnesium is one of the most common elements in the Earth’s crust. This alkaline earth metal is silvery white, and soft. As you perform this lab, think about why magnesium is used in emergency flares and fireworks. Farmers use it in fertilizers, pharmacists use it in laxatives and antacids, and engineers mix it with aluminum to create the BMW N52 6-cylinder magnesium engine block. Photographers used to use magnesium powder in the camera’s flash before xenon bulbs were available.

Most folks, however, equate magnesium with a burning white flame. Magnesium fires burn too hot to be extinguished using water, so most firefighters use sand or graphite.

We’re going to learn how to (safely) ignite a piece of magnesium in the first experiment, and next how to get energy from it by using it in a battery in the second experiment. Are you ready?

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Materials:

• magnesium strip (MSDS)
• matches with adult help
• tile or concrete surface (something non-flammable)
• gloves, goggles

Burning magnesium produces ultraviolet light. This isn’t good for your eyes, and the brightness of the flame is another danger for your eyes. Avoid looking directly into the flame.

Burning magnesium is so hot that if it gets on your skin it will burn to it and not come off. As difficult as burning magnesium is to put out, avoid letting the burning metal come in contact with you or anything else that might catch fire.

As explained later in this lab, magnesium burns in carbon dioxide. Therefore, a CO2 fire extinguisher won’t work to put it out. Water won’t work, CO2 won’t work. It takes a dry chemical fire extinguisher to put it out, or just wait for it to burn up completely on its own.

Magnesium is a metal, and in this experiment, you’ll find that some metals can burn. The magnesium in this first experiment combines with the oxygen in the air to produce a highly exothermic reaction (gives off heat and light). The ash left from this experiment is magnesium oxide:

2Mg _(s) + O_{2 (g)} –> 2Mg O _(s)

Not all the magnesium from this experiment turned directly into the ash on the table – some of it transformed into the smoke that escaped into the air.

Caution: Do NOT look directly at the white flame (which also contains UV), and do NOT inhale the smoke from this experiment!

C3000: Experiment 52

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

As you burn your magnesium, you will get your very own fireworks show….a little one, but still cool.

2Mg + O₂ –> 2MgO

Magnesium burned in oxygen yields magnesium oxide. Because the temperature of burning magnesium is so high, small amounts of magnesium react with nitrogen in the air and produce magnesium nitride.

3Mg + N₂ –> 2Mg₃N₂

Magnesium plus nitrogen yield magnesium nitride.  Magnesium will also burn in a beaker of dry ice instead of in air (oxygen).

2Mg + CO₂ –> 2MgO + C

Magnesium burned in carbon dioxide yields magnesium oxide and carbon (ash, charcoal, etc.)

Cleanup: Rinse off and pat dry the rest of the magnesium strip.

Storage: Place everything back in its proper place in your chemistry set.

Disposal: Dispose of all solid waste in the garbage.

Magnesium Battery

Now let’s see how to make a battery using magnesium, table salt, copper wire, and sodium hydrogen sulfate (AKA sodium bisulfate).

Materials:

• magnesium strip
• test tube and rack
• light bulb (from a flashlight)
• 2 pieces of wire
• measuring cup of water
• salt (sodium chloride)
• copper wire (no insulation, solid core)
• measuring spoon
• sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
• gloves, goggles

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet.  Handle this chemical only with gloves, and be sure to read over the MSDS before using.

C1000: Experiment 75
C3000: Experiment 295

We’re going to do another electrolysis experiment, but this time using magnesium instead of zinc. In the previous electrolysis experiment, we used electrical energy to start a chemical reaction, but this time we’re going to use chemical energy to generate electricity.  Using two electrodes, magnesium and copper, we can create a voltaic cell.

TIP: Use sandpaper to scuff up the surfaces of the copper and magnesium so they are fresh and oxide-free for this experiment.  And do this experiment in a DARK room.

How cool is it to generate electricity from a few strips of metal and salt water? Pretty neat! This is the way carbon-core batteries work (the super-cheap brands labeled ‘Heavy Duty’ are carbon-zinc or ‘dry cell’ batteries). However, in dry cell batteries scientists use a crumbly paste instead of a watery solution (hence the name) by mixing in additives.

In this chemical reaction, when the magnesium metal enters into the solution, it leaves 2 electrons behind and turns into a magnesium ion:

Oxidation: Mg _(s) –> Mg²⁺_(aq) + 2e^–

The magnesium strip takes on a negative charge (cathode), and the copper strip takes on a positive charge (anode).  The copper strip snatches up the electrons:

Reduction: Cu²⁺_(aq) + 2e^– –> Cu _(s)

and you have a flow of electrons that run through the wire from surplus (cathode) to shortage (anode), which lights up the bulb.

Note: You can substitute a zinc strip or aluminum strip for the magnesium strip and a carbon rod (from a pencil) for the copper wire.

Going further: You can expand on this experiment by substituting copper sulfate and a salt bridge to make a voltaic cell from two half-cells in Experiment 16.5 of the Illustrated Guide to Home Chemistry Experiments.

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This experiment is for advanced students.

In industry, hydrogen peroxide is used in paper making to bleach the pulp before they form it into paper. Biologists, when preparing bones for display, use peroxide to whiten the bones.

At home, 3% peroxide combined with ammonium hydroxide is used to give dark-haired people their desired blonde moment. Peroxide is also used on wounds to clean them and remove dead tissue. Peroxide slows the flow from small blood vessels and oozing in wounds as well.

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Peroxide is a chemical produced in a Bombardier Beetle, and it squirts its irritating load into the face or onto the lips of a predator. Zebra fish produce peroxide after their skin is damaged. This action acts as a signal to produce an abundance of white cells to fight any infection and assist in the healing.

Scientists believe that healing can occur in humans in the same way. Future experiments may prove them right. It is also believed that people who have asthma have elevated levels of peroxide in their lungs, levels much higher than people without asthma.

Hydrogen peroxide can also help an animal that has eaten poison. A small amount of it can be put down the animal’s throat to induce vomiting and clear the poison out of their body as much as possible. Did your dog get too close to a skunk? There is no real “cure” other than a lot of time outside to air out, but peroxide mixed with hand soap is pretty good at removing the stink. Then, how you remove that stink from yourself…..another problem.

Materials:

• 2 test tubes
• Burner
• Lighter
• Chemistry stand
• Test tube holder
• Glass jar
• Water pan
• Water
• Rubber tubing
• 90^o glass tubing
• 3% Hydrogen peroxide (H₂O₂) (MSDS)

Hydrogen peroxide comes in a dark bottle because sunlight will slowly decompose hydrogen peroxide in the same way that we are doing with the exception that our way is much quicker.

When finished heating hydrogen peroxide, if you leave everything together, water will climb the tubing and attempt to enter the hot test tube. Cold water and hot peroxide are not safely compatible. To avoid this, remove the stopper from the test tube and set it aside while the solution cools.

Wait until all the equipment is cool enough to touch before disassembling for cleaning and storage.

When heating the test tube, be careful. Don’t heat in one place for too long. Move the flame of the burner around periodically to heat the reaction area of the test tube uniformly.

Don’t boil the peroxide too vigorously. If boiling gets too wild, remove the burner form the test tube until it calms down, then move it back to heat again.

At all times, keep the flame and peroxide apart…well apart.

Hydrogen peroxide is going to get broken down, is going to decompose, into the base elements of hydrogen and oxygen.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Hydrogen peroxide (H₂O₂) breaks down with heat. A decomposition reaction occurs where hydrogen peroxide breaks down into its component elements, H₂ and O₂

2H₂O₂ –> 2H₂O + O₂

2 molecules of hydrogen peroxide are heated, creating a chemical decomposition reaction, producing 2 molecules of water and 1 molecule of oxygen.

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain

Going further: Elephant’s Toothpaste

A really fun experiment with hydrogen peroxide is making Elephant’s toothpaste. It requires an adult helper, and is fun for the kid and the adult.

Materials:

• Empty 20 or 24 ounce plastic bottle
• 3 % hydrogen peroxide
• Liquid dish soap
• Warm water
• Food coloring
• One packet or 2 1/2 ounces of yeast
• One really big container to contain the big mess – laundry tub, bathtub, etc.

This video below is a demonstration of the Elephant Toothpaste experiment using much nastier chemicals than the ones I’ve mentioned above… the hot gas generated is actually oxygen. Enjoy!

Procedure:

• Dissolve the yeast in a little warm water and stir well. Use just enough water to make a pourable liquid. Let it sit for about 5 minutes while you prepare the rest of the experiment.
• Pour 1/2 cup of hydrogen peroxide, 1/4 cup of dish soap and a little bit of food coloring in the bottle. Swirl to mix and put the bottle in the middle of your large pot, container or sink.
• Pour the yeast solution into the bottle. A funnel can help, but be prepared to pour fairly quickly and remove it again because the reaction will start as soon as you start pouring.
• Stand back and watch the fun!

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WARNING!! THIS EXPERIMENT IS PARTICULARLY DANGEROUS!! (No kidding.) This experiment is for advanced students.

We’ve created a video that shows you how to safely do this experiment, although if you’re nervous about doing this one, just watch the video and skip the actual experiment.

The gas you generate with this experiment is lethal in large doses, so you MUST do this experiment outdoors. We’ll be making a tiny amount to show how the chemical reactions of chlorine and hydrogen work.

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Hydrochloric acid is a strong acid. It is highly corrosive, which means that this acid will destroy or irreversibly damage another substance it comes in contact with. Simple terms….it is pretty nasty, so take special care when working with or around it.

HCl is used in processing leather, cleaning products, and in the food industry. We are most familiar with HCl in the form of Gastric Acid. HCl is in gastric acid and is one of the main ingredients in our stomach to aid in digestion of our food. In our lab we will produce hydrogen chlorine gas and add water to turn change it into hydrochloric acid.

Materials:

• Glass jar
• 90⁰ bend glass tubing
• One-hole rubber stopper
• Chemistry stand
• Wire mesh
• 2 Test tubes
• Test tube clamp
• Alcohol burner
• Lighter
• Tripod stand
• Sodium hydrogen sulfate (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
• Salt
• One-hole cork
• Medicine dropper
• Water
• Solid rubber stopper

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

Perform this experiment outdoors. If that is not a possibility, and you must do it inside, open doors and windows to provide lots of ventilation. Hydrogen chlorine gas inhalation can be fatal, but we are only producing a very small amount.

There are many steps in this lab, so go slow and steady. Read the lab over several times so you are sure what is going on and what is happening next.

When we shake the sodium hydrogen sulfate and the salt together in a stoppered test tube, we are trying to produce a heterogeneous mixture. Heterogeneous is a scientific word that means substance are mixed all together to be as one. A sample taken from one spot in the mixture should be the same as a sample taken from any other spot in the mixture.

At some point in this lab, we need to point the test tube containing the reaction slightly down. This is so the hydrogen chlorine gas can flow downhill. The gas is denser than air, so it will sink to the bottom of anything air filled…..like a room or a test tube.

Hydrogen chloride gas is poisonous – DO NOT INHALE!

When the medicine dropper / cork tool is placed in the water, water will be sucked up into the test tube. The water combines with the hydrogen chlorine gas to create hydrochloric acid.

A double replacement chemical reaction will take place in this experiment. A free hydrogen ion (+) and a free sodium ion (+) will be produced. Because their charges are alike, they cannot bond, but they can take each other’s place. The spots they each left are negatively charged after the hydrogen and sodium have departed. Opposites attract, and they reorganize into a double replacement reaction.

C3000: Experiment

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

NaCl + NaHSO₄ –> HCl + Na₂SO₄

Salt is combined with sodium hydrogen sulfate and heated to produce hydrochloric acid and sodium sulfate

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Our HCl needs to be neutralized before disposal. Put a bit of baking soda into the test tube. The contents should bubble as the neutralization is taking place. After neutralization, the liquid is safe, and can be washed down the drain. Solids are thrown in the trash.

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WARNING!! THIS EXPERIMENT IS PARTICULARLY DANGEROUS!! (No kidding.) This experiment is for advanced students.

We’ve created a video that shows you how to safely do this experiment, although if you’re nervous about doing this one, just watch the video and skip the actual experiment.

Bromine is a particularly nasty chemical, so be sure to very carefully follow the steps we’ve outlined in the video. You MUST do this experiment outdoors. We’ll be making a tiny amount to show how the chemical reactions involving bromine work.

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Isn’t it interesting how many ways we can use the same techniques and, by just changing a few chemicals, we can learn about so many different chemical reactions? This lab is similar in technique to the Generating Hydrochloric Acid lab. Using the same techniques, we will produce hydrogen bromide.

Hydrogen bromide (HBr) was used as a sedative in the late 1800s and early 1900s. Once they found out how poisonous it really was  (after enough people became blind and/or dead), someone had the wonderful idea that maybe we shouldn’t use it anymore. It was also used to control epilepsy until the substitute Phenobarbital came on the scene in 1911. HBr is still used to treat epilepsy in dogs. In cats HBr causes inflammation of the lungs and makes for a very unhappy cat.

Materials:

• Alcohol burner
• Lighter
• Wire screen
• Tripod stand
• Glass jar
• Rubber tubing
• 900 Glass tubing
• One-hole rubber stopper
• Chemistry stand
• Test tube holder
• Test tube
• Potassium bromide (KBr) (MSDS)
• Sodium hydrogen sulfate (NaHSO₄) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
• Burette
• Water
• Sodium carbonate (Na₂CO₃) (MSDS)
• Silver nitrate (AgNO₃) (MSDS)

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet.  Handle this chemical only with gloves, and be sure to read over the MSDS before using.

Maintain good and proper lab techniques. We are working with some nasty stuff in this lab. We need to perform this lab outdoors if possible, or indoors with lots of ventilation. The reaction advances in stages:

• Bubbles in the burette tell us the reaction is occurring.
• Brown streaks will appear in the water contained in the glass jar as gas collects there.
• Brown vapor will begin to appear in the test tube. When the reaction is complete, the test tube will contain lots of brown vapor.

After we produce HBr, we will perform a number of tests to see if it is an acid or a base.

1. Test contents of test tube with blue litmus paper. Red color change indicates an acid.
2. Add baking soda to the HBr. Bubbles and the solution turning white. HBr is an acid in this test because it is obviously reacting with a base.
3. If a magnesium strip placed in the HBr corrodes, or starts to dissolve, then HBr is an acid.
4. With the addition of silver nitrate to the HBr, if a white cloudiness occurs and crystals form in the bottom of the test tube, then HBr is an acid.

C3000: Experiments 134-138

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

KBr    +    NaHSO₄ –>    HBr    +    KNaSO₄

Potassium bromide and sodium hydrogen sulfate, when heated, produce hydrogen bromide and potassium sodium sulfate.

Cleanup: We are going to clean everything thoroughly after we finish the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place cleaned tools and glassware in their respective storage places.

Disposal: Liquids can be washed down the drain. Solids are thrown in the trash.

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This experiment is for advanced students.

Zinc and Hydrogen are important elements for all of us. Zinc (Zn) metal is element #30 on the periodic table. Lack of zinc in our diets will delay growth of our bodies and can kill.

Hydrogen gas (H) is element #1 on the periodic table. Hydrogen was discovered in the 1500s. In a pure state, hydrogen combustion (in small quantities) is interesting. In large amounts, mixed with oxygen, the explosion can be devastating.

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We are going to perform an experiment that generates a small amount of hydrogen gas, with a correspondingly small explosion. Hydrogen is violently flammable in air, but by itself….not so much. Hydrogen is lighter than air, so has been used in airships, or blimps. The Hindenburg, a German airship filled with hydrogen, burned up quickly on May 6, 1937 while tied to a mooring mast.

Currently, hydrogen is being thought of as the “fuel of the future” for our cars and other vehicles. Most the Earth’s our hydrogen is contained in water (H₂O). Most of the experimentation has been in producing hydrogen through electrolysis. That proves very expensive to produce and transport. Until a cheaper alternative appears, hydrogen (H₂) is not a practical alternative.

Scientists are lately giving a lot of attention to a process that will produce hydrogen cheaply and easily.  That method is to heat zinc powder in the presence of air (oxygen). It can be achieved at low temperatures, little cost, and little danger – perfect for a hydrogen fuel cell in our car. Don’t go filling your tank with it right away, though. Engineers still need to work some bugs out. It will happen soon, so be patient. (And remember, you saw it first in your chemistry set!)

Materials:

• Gloves
• Goggles
• Chemistry stand
• Zinc (Zn) powder (MSDS)
• Measuring spoon
• 4 test tubes
• Test tube holder
• Alcohol burner
• Lighter
• One-hole rubber stopper
• Rubber tubing
• 90⁰ bend glass tubing
• Water
• Measuring syringe
• Stirring rod
• Clear pan

Important! Dispose of the Zinc (Zn) left in the test tube in the outside trash. Accidentally ingesting (and it should only be accidental) of Zinc (Zn) or Zinc Chloride (ZnCl), will harm you or animals. It will not be one of your best days. Call 911 if this happens.

After you have finished your experiment, be careful of the hot test tube containing the zinc compound. The test tube is very hot, and there will be a difference in pressure between the water tank and the test tube. Because the test tube has been heated, the pressure is less than atmospheric pressure.

As it cools, the water in the tank, which is at atmospheric pressure (the pressure of the air in the room) is higher than in the test tube. The test tube’s low pressure is looking to suck something, anything, up the glass tube. The water, sitting there at normal air pressure, notices the need. Water climbs up the tube  in response to the test tube’s request.

At the conclusion of the experiment, with the heat off, the test tube starts to cool and water then donates some stuff to equalize the pressure. If allowed to , that cool water hits that hot zinc, or hot test tube, and the test tube could explode and the zinc could quickly react, blowing out the stopper and spewing hot zinc all over you.

Here is the safety information for the products in this chemical reaction:

• Zinc Oxide (MSDS)
• Hydrogen (MSDS)

You first put zinc powder and water together in the end of the horizontally held test tube. But why place a pile of, dry zinc, laying in the test tube near the wet zinc? We want to create a chemical reaction with zinc and water. Wet zinc powder in the end of the test tube allows the dry zinc to come in contact with water when they are both heated without the powder actually getting wet. This way the reaction occurs faster and more efficiently. We don’t have to wait any longer than necessary this way.

C3000: Experiments 67-69

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

In this experiment we are causing a single replacement reaction to occur between zinc powder and water. In a replacement reaction, a compound breaks down into its elemental parts in the first stage of the chemical reaction. A new compound is created as the elements search about for something to bond with to satisfy their needs to gain or give up electrons.

Zn + H₂O –> ZnO + H₂

Zinc powder reacts with water under the influence of heat to become zinc oxide and hydrogen gas. The new compound is called zinc oxide (ZnO).

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three more times. Dry them before putting them away.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the outside garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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This experiment shows how a battery works using electrochemistry. The copper electrons are chemically reacting with the lemon juice, which is a weak acid, to form copper ions (cathode, or positive electrode) and bubbles of hydrogen.

These copper ions interact with the zinc electrode (negative electrode, or anode) to form zinc ions. The difference in electrical charge (potential) on these two plates causes a voltage.

Materials:

• one zinc and copper strip
• two alligator wires
• digital multimeter
• one fresh large lemon or other fruit

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Download Student Worksheet & Exercises

Roll and squish the lemon around in your hand so you break up the membranes inside, without breaking the skin or leaking any juice. If you’re using non-membrane foods, such as an apple or potato, you are all ready to go.

Insert the copper and zinc strips into the lemon, making sure they do not contact each other inside. Clip one test wire to each metal strip using alligator wires to connect to the digital multimeter. Read and record your results.

What happens when you gently squeeze the lemon? Does the voltage vary over time?

You can try potatoes, apples, or any other fruit or vegetable containing acid or other electrolytes. You can use a galvanized nail and a copper penny (preferably minted before 1982) for additional electrodes.

If you want to light a light bulb, try using a low-voltage LED in the 1.7V or lower hooked up to several lemons connected in series. For comparison, you’ll need about 557 lemons to light a standard flashlight bulb.

What’s going on?

The basic idea of electrochemistry is that charged atoms (ions) can be electrically directed from one place to the other. If we have a glass of water and dump in a handful of salt, the NaCl (salt) molecule dissociates into the ions Na+ and Cl-.

When we plunk in one positive electrode and one negative electrode and crank up the power, we find that opposites attract: Na+ zooms over to the negative electrode and Cl- zips over to the positive. The ions are attracted (directed) to the opposite electrode and there is current in the solution.

Electrochemistry studies chemical reactions that generate a voltage and vice versa (when a voltage drives a chemical reaction), called oxidation and reduction (redox) reactions. When electrons are transferred between molecules, it’s a redox process.

Fruit batteries use electrolytes (solution containing free ions, like salt water or lemon juice) to generate a voltage. Think of electrolytes as a material that dissolves in water to make a solution that conducts electricity. Fruit batteries also need electrodes made of conductive material, like metal. Metals are conductors not because electricity passes through them, but because they contain electrons that can move. Think of the metal wire like a hose full of water. The water can move through the hose. An insulator would be like a hose full of cement – no charge can move through it.

You need two different metals in this experiment that are close, but not touching inside the solution. If the two metals are the same, the chemical reaction doesn’t start and no ions flow and no voltage is generated – nothing happens.

Exercises

1.  What kinds of fruit make the best batteries?
2.  What happens if you put one electrode in one fruit and one electrode in another?
3.  What happens if you stick multiple electrode pairs around a piece of fruit, and connect them in series (zinc to copper to zinc to copper to zinc…etc.) and measure the voltage at the start and end electrodes?

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When an atom (like hydrogen) or molecule (like water) loses an electron (negative charge), it becomes an ion and takes on a positive charge. When an atom (or molecule) gains an electron, it becomes a negative ion. An electrolyte is any substance (like salt) that becomes a conductor of electricity when dissolved in a solvent (like water).

This type of conductor is called an ‘ionic conductor’ because once the salt is in the water, it helps along the flow of electrons from one clip lead terminal to the other so that there is a continuous flow of electricity.

This experiment is an extension of the Conductivity Tester experiment, only in this case we’re using water as a holder for different substances, like sugar and salt. You can use orange juice, lemon juice, vinegar, baking powder, baking soda, spices, cornstarch, flour, oil, soap, shampoo, and anything else you have around. Don’t forget to test out plain water for your ‘control’ in the experiment!

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Here’s what you need:

• 2 AA batteries
• AA battery case
• 2 alligator clips
• LED
• water
• salt
• glass jar (like a clean jam jar)

Download Student Worksheet & Exercises

Exercises

1. Why does electricity flow through some solutions but not all of them?
2. What is a salt?
3. How are electrolytes used today in real life?
4. Which substance was your top conductor?
5. Which substance didn’t conduct anything at all?
6. What happens if you mix an electrolyte and non-electrolyte together?

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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^– –> H_2(g)

2 H₂O_(l) + 2e^– –> H_2(g) + 2 OH^–_(aq)

The oxidation reaction is occurring at the positively charged anode as oxygen is being generated:

2 H₂O_(l)  –> O_2(g) + 4 H⁺_(aq) + 4e^–

4 OH^–_(aq) –> O_2(g) + 2 H₂O_(l) + 4 e-

Overall reaction:

2 H₂O_(l)  –> 2 H_2(g) + O_2(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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Electricity. Chemistry. Nothing in common, have nothing to do with each other. Wrong! Electrochemistry has been a fact since 1774. Once electricity was applied to particular solutions, changes occurred that scientists of the time did not expect.

In this lab, we will discover some of the same things that Farraday found over 300 years ago. We will be there as things tear apart, particles rush about, and the power of attraction is very strong. We’re not talking about dancing, we’re talking about something much more important and interesting….we’re talking about ELECTROCHEMISTRY!

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Materials:

• Test tube rack
• 9V battery clip
• 9V battery
• Flashlight lamp
• Gloves
• Electrical wires
• Aluminum foil
• Water
• Sugar
• Salt
• Sodium carbonate (MSDS)
• Measuring spoon

When the salt sodium chloride (NaCl) mixes with water, it separates into its positively (Na+) and negatively (Cl-) charged particles (ions). When a substance mixes with water and separates into its positive and negative parts, it’s called a ‘salt’.

Salts can be any color of the rainbow, from the deep orange of potassium dichromate to the vivid purple of potassium permanganate to the inky black of manganese dioxide. Did you know that MSG (monosodium glutamate) is a salt? Most salts are not consumable, as in the lead poisoning you’d get if you ingested lead diacetate.

If you pass a current through the solution of salt and water, opposites attract: the positive ions are attracted tot he negative pole and the negative ions go toward the positive pole. These migrations ions allow electricity to flow, which is why ‘salt’ solutions conduct electricity.

C1000: Experiments 66-70

Download Student Worksheet & Exercises

Here’s what’s going on in this experiment:

Our experiment uses a saturated solution of table salt that is just sitting in a container minding its own business. That just won’t do! We must intervene. Our 9V battery pushes its voltage through the saltwater. That electric current tears the sodium from the chlorine. These positively and negatively charged ions rush about, looking for something they are attracted to. Opposites attract, so positively charged sodium ions find spending time with the negative electrode a treat. They are very happy together. Negatively charged chlorine ions are attracted to the positive electrode. The match is wonderful, and the negativity and the positivity somehow enjoy the time spent with each other.

NaCl –> Na⁺ + Cl^–

Sodium chloride decomposes into sodium and chlorine ions

Cleanup: Clean everything thoroughly after you are finished with the lab. After cleaning with soap and water, rinse thoroughly. Chemists use the rule of “three” in cleaning glassware and tools. After washing, chemists rinse out all visible soap and then rinse three times more.

Storage: Place all chemicals, cleaned tools, and glassware in their respective storage places.

Disposal: Dispose of all solid waste in the garbage. Liquids can be washed down the drain with running water. Let the water run awhile to ensure that they have been diluted and sent downstream.

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Ammonia has been used by doctors, farmers, chemists, alchemists, weightlifters, and our families since Roman times. Doctors revive unconscious patients, farmers use it in fertilizer, alchemists tried to use it to make gold, weightlifters sniff it into their lungs to invigorate their respiratory system and clear their heads prior to lifting tremendous loads. At home, ammonia is used to clean up the ketchup you spilled on the floor and never cleaned up.

The ammonia molecule (NH₃) is a colorless gas with a strong odor – it’s the smell of freshly cleaned floors and windows. Mom is not cleaning with straight ammonia (it’s gas at room temperature because it boils at -28^oF, so the stuff she cleans with is actually ammonium hydroxide, a solution of ammonia and water). Ammonia is found when plants and animals decompose, and it’s also in rainwater, volcanoes, your kidneys (to neutralize excess acid), in the ocean, some fertilizers, in Jupiter’s lower cloud decks, and trace amounts are found in our own atmosphere (it’s lighter than air).

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Ammonia is a strong base – it combines with acids to form salts:

NH₃ + HCl –> NH₄Cl

But ammonia also can act as a weak acid. Remember, an acid is a proton donor, as in this reaction with lithium, where the ammonia molecule donated one hydrogen atom:

2 Li + 2 NH₃ –> 2 LiNH₂ + H₂

In this experiment, we make a stink and then we see something that will make us go ooooooh…and aaaaw. How fun is that? But you need to follow the instructions carefully and perform your experiment safely. Promise?

Ammonia will be generated by the combination of ammonium chloride and sodium carbonate. The amount of ammonia generated in this experiment is not a large amount. However, you really should experience this particular stink.

Materials:

• 3 test tubes and rack
• sodium carbonate (MSDS)
• ammonium chloride (MSDS)
• copper sulfate (MSDS)
• sodium hydrogen sulfate (NaHSO4) (MSDS) Sodium hydrogen sulfate is very toxic. Respect it, handle it carefully and responsibly. Do not take it for granted.
• water
• test tube stopper
• measuring spoon
• gloves, goggles

NOTE: Be very careful when handling the sodium hydrogen sulfate – it’s highly corrosive and dangerous when wet. Handle this chemical only with gloves, and be sure to read over the MSDS before using.

A chemical reaction is going to occur when the ammonium chloride, sodium chloride, and another chemical reaction is going to occur when the copper sulfate is added. These compounds are the reactants in our chemical reaction, and the blue liquid, CuCl (copper chloride), at the end of the experiment, will be our product. This experiment displays two types of reactions, a decomposition reaction when we combine ammonium chloride and sodium chloride, and a double replacement reaction when we add copper sulfate to the mixture.

C1000: Experiments

Download Student Worksheet & Exercises

When we combine ammonium chloride and sodium carbonate, ammonia will be produced. We will add copper sulfate to that mixture, producing two chemical compounds with totally different properties from those exhibited by the original chemicals.

Two chemical reactions will occur in this experiment:

(1) When you add ammonium chloride and sodium chloride to the water, a decomposition reaction will occur that produces ammonia gas, carbon dioxide gas, and sodium chloride dissolved in water. It is identified as a decomposition reaction because the reactants breakdown into elements or simpler compounds.

NaHCO₃ + 2NH₄Cl –> NH₃ + CO₂ + NaCl + 2H₂O

sodium carbonate + ammonium chloride –> ammonia + carbon dioxide + sodium chloride + water

(2) The next reaction takes place when copper sulfate is added to the sodium chloride and water. The products of this reaction are sodium sulfate and copper chloride (the blue color). This reaction is identified as a double replacement reaction due to the fact that the two reactants break apart and recombine, the reactants trading parts, recombining to form two other different compounds with properties completely different than those of the reactants.

NaCl + CuSO₄ —> NaSO₄ + CuCl

sodium chloride + copper sulfate –> sodium sulfate + copper chloride

Big suggestion here: All chemical vapors are best experienced by “wafting”, a procedure that brings the vapor to you, instead of sticking your nose in the test tube, bringing you to the vapors. Please get in the habit of smelling properly. If ammonia vapors can bring unconscious people back to consciousness, you should probably make sure you are sniffing safely.

Reminder: Always wash your hands or gloves, and your chemistry tools, when switching from one chemical to another to avoid contamination that could affect the experiment adversely.

Store: Put all chemicals away in their proper places to keep them organized and ready to be used again. All tools should be put away as well, but make sure hat they have been cleaned and dried before storing them. A rule of thumb in chemistry is always wash something three times.

Disposal: Pour liquids down the drain using plenty of water. Throw solid waste into the outside garbage to prevent filling the house with bad smells.

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This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

We’re going to be mixing up dinosaur toothpaste, doing experiments with catalysts, discovering the 5 states of matter, and building your own chemistry lab station as we cover chemical kinetics, phase shifts, the states of matter, atoms, molecules, elements, chemical reactions, and much more. We’re also going to turn liquid polymers into glowing putty so you can amaze your friends when it totally glows in the dark. AND make liquids freeze by heating them up (no kidding) using a scientific principle called supercooling,

Materials:

• Chemistry Worksheet
• Aluminum pie plate
• Bowl
• Clear glue or white glue
• Disposable cups
• Goggles & gloves
• Hydrogen peroxide
• OPTIONAL: Instant reusable hand warmer (containing sodium acetate )
• Liquid soap
• Popsicle sticks
• Scissors or pliers
• Sodium tetraborate (also called “Borax”)
• Water bottle
• Yeast
• Yellow highlighter
• Optional: If you want to see your experiments glow in the dark, you’ll need a fluorescent UV black light (about $10 from the pet store – look in cleaning supplies under “Urine-Off” for a fluorescent UV light). UV flashlights and UV LEDs will not work.

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[/am4show]

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!

We’re ready to deal with the topic you’ve all been waiting for! Join me as we find out what happens to stars that wander too close, how black holes collide, how we can detect super-massive black holes in the centers of galaxies, and wrestle with question: what’s down there, inside a black hole?

Materials:

• marble
• metal ball (like a ball bearing) or a magnetic marble
• strong magnet
• small bouncy ball
• tennis ball and/or basketball
• two balloons
• bowl
• 10 pennies
• saran wrap (or cup open a plastic shopping bag so it lays flat)
• aluminum foil (you’ll need to wrap inflated balloons with the foil, so make sure you have plenty of foil)
• scissors

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Key Concepts

What’s a black hole made of? Black holes are make of nothing but space and time, and they are the strangest things in nature.  It’s BLACK because does not emit or reflect light.  Black holes are the darkest black in the universe – no matter how powerful of a light you shine on it, even if it’s a million watt flashlight, no light ever bounces back, because its truly a ‘hole’ in space.

And a HOLE means nothing entering can escape. Anything that crosses the edge is swallowed forever. Scientists think of black holes as the edge of space, like a one-way exit door.

Biggest myth about black holes: Black holes are not vacuum cleaners with infinite sized bags. They do not roam around the universe sucking up everything they can find. They will grow gradually as stars and matter falls into them, but they do not seek out prey like predators. It just sits there with its mouth open, waiting for dinner.

Here’s an example of what a black hole is: If you take a ball and toss it up in the air, does it come back down to you? Sure! Toss it up even higher now… and it still comes back, right? What if you toss it up so fast that it exceeds the escape velocity of earth? (7 miles per second) Will it ever come back? No. The escape velocity depends on the gravitational pull of an object. The escape velocity of the sun is 400 miles per second. A black hole is an object that has an escape velocity greater than the speed of light. That’s exactly what a black hole is.

So, a black hole is a region where gravity is so strong that any light that tries to escape gets dragged back.  Because nothing can travel faster than light, everything else gets dragged back too!

Another interesting fact about black holes is that they are a place where gravity is so intense that time stops. This means that an object that falls into a black hole will never reappear, because they are frozen in time.

I often hear the question – how big are black holes? There’s no limit to the size of a black hole – it can be as large or as small as you can imagine it to be (and then some!). The more massive a black hole is, the more space it will take up, and the larger the radius of the event horizon. One of the largest and heaviest black holes is actually the super massive black hole at the center of our own Milky Way galaxy, about 30,000 light years away. Don’t worry, since it’s so far away and it’s not actively feeding.

Black holes are believed to be able to evaporate. Steven Hawking suggested that black holes aren’t exactly all black, but they emit a tiny bit of radiation, which comes directly from the black hole’s mass. This means as the black hole emits radiation, it loses mass, and shrinks.

If you’re looking for black holes, the nearest one is called V4641 Sgr and it’s 1,600 light years away in the Sagittarius arm of the Milky Way.  This is actually a rare type of black hole called a micro quasar. Click here for a downloadable Map of Black Holes.

One of the biggest misconceptions about black holes is that they are thought to be giant vacuum cleaners with infinitely large bags. Actually, they don’t go around vacuuming up all the matter they find. (If they did, they would eventually inhale all the matter in the universe and there’s be nothing left but black holes.) In fact, black holes can’t suck up all the matter because each black hole has its very own event horizon, which means that matter has to first cross that horizon in order to be eaten by the black hole. If it doesn’t go past that horizon, then it will not be sucked into the black hole.

Still crazy for black holes? Download the Exploring Black Holes PDF poster file and also try playing the Black Hole Space Travel game, which was developed by a team of NASA scientists. Enjoy!

Questions to Ask

1. What are three different ways to detect a black hole?
2. How many ways can a black hole kill you? Can you name them?
3. What happens if you get close to a black hole, but not close enough to get sucked in? (Remember your magnet-marble experiment!)
4. What if you watch someone get sucked in? What does it look like?
5. What’s the most interesting thing you learned from the video about black holes?
6. Why does a supernova explode? (Remember your two-ball experiment?)
7. What causes a black hole to form?
8. Does a black hole search for its next victim?
9. Where is the closest super-massive black hole?
10. What is gravitational lensing and why does it work? (Remember your marble-bowl experiment!)

[/am4show]

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too

Our solar system includes rocky terrestrial planets (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), ice giants (Uranus and Neptune), and assorted chunks of ice and dust that make up various comets and asteroids.

Did you know you can take an intergalactic star tour without leaving your seat? To get you started on your astronomy adventure, I have a front-row seat for you in a planetarium-style star show. I usually give this presentation at sunset during my live workshops, so I inserted slides along with my talk so you could see the pictures better. This video below is long, so I highly recommend doing this with friends and a big bowl of popcorn. Ready?
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Materials:

• Two balls, one larger than the other (like a soccer and a tennis ball, or bouncy ball and tennis ball)
• Print out this worksheet to fill in as we go along!

Download the Black Hole Explorer Game. This was created by a team of scientists, you can use this set of instructions to build your own black hole board game. It plays two different ways: competitively and cooperatively. Black Hole Explorer was created for NASA by the Harvard-Smithsonian Center for Astrophysics.

This is a PDF download, so you’ll need Adobe Acrobat Reader to view the file. It’s fun, easy, and totally free for your family and students to enjoy!

Key Concepts

The solar system is the place that is affected by the gravity our sun. Our solar system includes rocky terrestrial planets (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), ice giants (Uranus and Neptune), and assorted chunks of ice and dust that make up various comets and asteroids. The eight planets follow a near-circular orbit around the sun, and many have moons.

Two planets (Ceres and Pluto) have been reclassified after astronomers found out more information about their neighbors. Ceres is now an asteroid in the Asteroid Belt between Mars and Jupiter. Beyond Neptune, the Kuiper Belt holds the chunks of ice and dust, like comets and asteroids as well as larger objects like dwarf planets Eris and Pluto.

Beyond the Kuiper belt is an area called the Oort Cloud, which holds an estimated 1 trillion comets. The Oort Cloud is so far away that it’s only loosely held in orbit by our sun, and constantly being pulled gravitationally by passing stars and the Milky Way itself. The Voyager Spacecraft are beyond the heliosphere (the region influenced gravitationally by our sun) but has not reached the Oort Cloud.

Our solar system belongs to the Milky Way galaxy. Galaxies are stars that are pulled and held together by gravity. Globular clusters are massive groups of stars held together by gravity, using housing between tens of thousands to millions of stars. Some galaxies are sparse while others are packed so dense you can’t see through them. Galaxies also like to hang out with other galaxies (called galaxy clusters ), but not all galaxies belong to clusters, and not all stars belong to a galaxy.

After a star uses up all its fuel, it can either fizzle or explode. Planetary nebulae are shells of gas and dust feathering away. Neutron stars are formed from stars that go supernova, but aren’t big and fat enough to turn into a black hole. Pulsars are spinning neutron stars with their poles aimed our way. Neutron stars with HUGE magnetic fields are known as magnetars. Black holes are the leftovers of a BIG star explosion. There is nothing to keep it from collapsing, so it continues to collapse forever. It becomes so small and dense that the gravitational pull is so great that light itself can’t escape.

The sun holds 99% of the mass of our solar system. The sun’s equator takes about 25 days to rotate around once, but the poles take 34 days. You may have heard that the sun is a huge ball of burning gas. But the sun is not on fire, like a candle. You can’t blow it out or reignite it. So, where does the energy come from?

The nuclear reactions deep in the core transforms 600 million tons per second of hydrogen into helium. This gives off huge amounts of energy which gradually works its way from the 15 million-degree Celsius temperature core to the 15,000 degree Celsius surface.

Active galaxies have very unusual behavior. There are several different types of active galaxies, including radio galaxies (edge-on view of galaxies emitting jets), quasars (3/4 view of the galaxy emitting jets), blazars (aligned so we’re looking straight down into the black hole jet), and others. Our own galaxy, the Milky Way, has a super-massive black hole at its center, which is currently quiet and dormant.

Dying stars blow off shells of heated gas that glow in beautiful patterns. William Hershel (1795) coined the term ‘planetary nebula’ because the ones he looked at through 18th century telescopes looked like planets. They actually have nothing to do with planets – they are shells of dust feathering away.

When a star uses up its fuel, the way it dies depends on how massive it was to begin with. Smaller stars simply fizzle out into white dwarfs, while larger stars can go supernova. A recent supernova explosion was SN 1987. The light from Supernova 1987A reached the Earth on February 23, 1987 and was close enough to see with a naked eye from the Southern Hemisphere.

Questions to Ask

1. What’s your favorite part about Jupiter?
2. Which planet is NOW your favorite (after listening to the slide show presentation)?
3. What happened to the stars in the last slide of the show?
4. How many moons around Jupiter or Saturn can you see with binoculars?
5. What’s the difference between a galaxy and a black hole?
6. How many Earths fit inside the sun?

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This is a recording of a recent live class I did with an entire high school astronomy class. I’ve included it here so you can participate and learn, too!

Light is energy that can travel through space. How much energy light has determines what kind of wave it is. It can be visible light, x-ray, radio, microwave, gamma or ultraviolet. The electromagnetic spectrum shows the different energies of light and how the energy relates to different frequencies, and that’s exactly what we’re going to cover in class. We’re going to talk about light, what it is, how it moves, and it’s generated, and learn how astronomers study the differences in light to tell a star’s atmosphere from  millions of miles away.

I usually give this presentation at sunset during my live workshops, so I inserted slides along with my talk so you could see the pictures better. This video below is long, so I highly recommend doing this with friends and a big bowl of popcorn. Ready?

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Materials:

• Hair (one strand)
• Tape
• Pencil
• Ruler or yardstick
• Paper
• Calculator
• Red laser
• Flashlight
• Glass of water
• Large chocolate bar
• Microwave
• Plate
• Orange highlighter
• Diffraction grating OR use an old CD
• Print out this worksheet to fill in as we go along!

[/am4show]

This is a beefier-version of the Electric Eye that will be be able to turn on a buzzer instead of a LED by increasing the voltage in the circuit. This type of circuit is a light-actuated circuit. When a beam of light hits the sensor (the “eye”), a buzzer sounds. Use this to indicate when a door closes or drawer closes… your suspect will never know what got triggered.
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Materials:

• Red laser (cheap dollar store kind works well)
• 9V Battery
• Three alligator clip leads
• Buzzer (3-6V)
• CdS Cell

Download Student Worksheet & Exercises

Exercises

1. How is this circuit different from the Electric Eye experiment we did previously?
2.  Name three other light sources that work to activate your circuit.

[/am4show]

Today you get to concentrate light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot.

Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes by bending the light. When light passes through a different medium (from air to glass, water, a lens…) it changes speed and usually the angle at which it’s traveling. A prism splits incoming light into a rainbow because the light bends as it moves through the prism. A pair of eyeglasses will bend the light to magnify the image.

Materials

• Sunlight
•  Glass jar
• Nail that fits in the jar
•   12” thread
•   Hair from your head
• 12” string
• 12” fishing line
• 12” yarn
•  Paperclip
• Magnifying glass
•  Fire extinguisher
•  Adult help

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Download Student Worksheet & Exercises

1. You’re going to concentrate the power of the Sun on a flammable surface.
2. Please do this on a fireproof surface! This experiment will damage tables, counters, carpets, and floors. Do this experiment on a fireproof surface, like concrete or blacktop.
3. Hold the magnifier above the leaf and bring it down toward the leaf until you see a bright spot form on its surface. Adjust it until you see the light as bright and as concentrated as possible. First, you’ll notice smoke, then a tiny flame as the leaf burns.
4. You are concentrating the light, specifically the heat, from the Sun into a very small area. Normally, the sunlight would have filled up the entire area of the lens, but you’re shrinking this down to the size of the dot that’s burning the leaf.
5. Thermoelectric power plants use this principle to power entire cities by using this principle of concentrating the heat from the Sun.
6. Never look through anything that has lenses in it at the Sun, including binoculars or telescopes, otherwise what’s happening to the leaf right now is going to happen to your eyeball.
7. Now for the next part of the lab, do not use water bottles – you want something that doesn’t melt, like a glass jar from the pickles or the mayo.
8. Remove the lid and punch a hole in the center. Use a drill with a ¼” drill bit or smaller, or a hammer and nail.
9. Screw the lid on the jar.
10. Tie one end of the thread to the paperclip.
11. Poke the other end of the thread inside the hole on the lid.
12. Unscrew the lid and tie a nail to the other end of the thread. You want the nail to be hanging above the bottom of the jar by an inch or two, so adjust the height as needed.
13. Bring your jar outside.
14. Question: Without breaking the glass or removing the lid, how can you get the nail to drop to the bottom of the jar?

What’s Going On?

Magnifying lenses, telescopes, and microscopes use this idea to make objects appear different sizes by bending the light. When light passes through a different medium (from air to glass, water, a lens…) it changes speed and usually the angle at which it’s traveling. A prism splits incoming light into a rainbow because the light bends as it moves through the prism. A pair of eyeglasses will bend the light to magnify the image.

Exercises

1. What happened to the leaf? Why?
2. How did you get the nail to drop?
3. Which material ignited the quickest?

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This is a recording of a recent live class I did with an entire high school astronomy class. I’ve included it here so you can participate and learn, too!

Light is energy that can travel through space. How much energy light has determines what kind of wave it is. It can be visible light, x-ray, radio, microwave, gamma or ultraviolet. The electromagnetic spectrum shows the different energies of light and how the energy relates to different frequencies, and that’s exactly what we’re going to cover in class. We’re going to talk about light, what it is, how it moves, and it’s generated, and learn how astronomers study the differences in light to tell a star’s atmosphere from  millions of miles away.

I usually give this presentation at sunset during my live workshops, so I inserted slides along with my talk so you could see the pictures better. This video below is long, so I highly recommend doing this with friends and a big bowl of popcorn. Ready?

[am4show have=’p8;p9;p11;p38;p92;p96;’ guest_error=’Guest error message’ user_error=’User error message’ ]

Materials:

• Hair (one strand)
• Tape
• Pencil
• Ruler or yardstick
• Paper
• Calculator
• Red laser
• Flashlight
• Glass of water
• Large chocolate bar
• Microwave
• Plate
• Orange highlighter
• Diffraction grating OR use an old CD
• Print out this worksheet to fill in as we go along!

[/am4show]