Physics is your big chance to show off your inner artist by drawing what you see through a scientists eyes in a special way so others can understand your big ideas. We're going to practice making models in our mind of what's going on in the real world, and learning how to write it down on paper using the language of mathematics so you can communicate with others and work together designing your inventions and predicting what might happen next. All scientists, engineers, technicians, including folks like Feynman and Einstein, learned how to represent the real world on paper in a visual way using diagrams. (Although Nobel prize winner Dr. Richard Feynman got frustrated and invented his own diagrams, which we still use today in quantum mechanics.)

Please login or register to read the rest of this content.

Graphs are used all over the field of physics, and the p-t and v-t graphs are the ones used most for moving objects, especially when describing the projectile motion of objects. With one peek at the graph, you can tell a lot about what's going on, which is one reason they are so useful. You don't have to pour over pages of equations to get a sense of what's going on with the experiment.

Please login or register to read the rest of this content.

The position-time “p-t” graph is one that gets used a lot, and since it's axes are position and time, the slope of the line will give average velocity to describe the motion of an object.  If the velocity is constant, then the slope is constant and you'll see a straight line (either uphill or downhill). If velocity is changing, you'll see a curved rather than straight line for the slope. A steeper line indicates larger velocity. An uphill slope means positive velocity, downhill indicates negative velocity. If the slope is downhill and curved, but it starts out like a skier on a bunny hill, then the negative velocity starts slow and moves fast as time goes on, which is a sign of negative acceleration (starting slow and speeding up). If the slope looks instead like starting at the top of a black diamond run, then the object starts with a high negative velocity but ends with a slower velocity, a indication of positive acceleration.

Please login or register to read the rest of this content.

The velocity-time “v-t” graphs are another common type of graph you'll run across that describe motion of an object. The shape and slope of the lines on the graph will tell you a lot about what's going on with the motion of the object, and here's how you decipher it:  If the line is a straight, horizontal line, then the velocity stayed constant and there's no acceleration, like when you're driving on the freeway. Your car is moving at a steady 65 mph in a straight line.

However, if you're at a stoplight that just turned green, you're going to start changing your velocity by increasing your speed, giving you a positive acceleration. The graph will be a straight line starting at the origin and moving uphill. The slope of the line is positive, indicating your positive acceleration.

So can you tell if an object is moving in a positive or negative direction? Yes! A positive velocity means an object is moving in a positive direction, so if the line is in the positive region of the graph, you know it's traveling in a positive direction.  By the same logic, if the slope is in the negative regions of the graph, the object is traveling in a negative direction. For slopes crossing the axis, the object is changing directions.

Can you figure out if an object is speeding up or slowing down? Yes again! Speeding up means that the magnitude of the velocity is increasing in value (the number only, ignoring the plus or minus sign), so if the line is moving away from the x-axis, it's speeding up. And if it's approaching the x-axis, it's slowing down.

Please login or register to read the rest of this content.

This experiment is one of my favorites in this acceleration series, because it clearly shows you what acceleration looks like. The materials you need is are:

• a hard, smooth ball (a golf ball, racket ball, pool ball, soccer ball, etc.)


• tape or chalk


• a slightly sloping driveway (you can also use a board for a ramp that's propped up on one end)

For advanced students, you will also need: a timer or stopwatch, pencil, paper, measuring tape or yard stick, and this printout.

Grab a friend to help you out with this experiment - it's a lot easier with two people.

Are you ready to get started really discovering what acceleration is all about?

Here's what you do: Please login or register to read the rest of this content.

Please login or register to read the rest of this content.

Click here to go to next lesson on Describing Motion with Equations