Using a Computer Simulation

So far we have tried to imagine the energy diagrams if friction could be removed. Because we cannot magically remove the friction from the toy cars, you will use a computer program to explore the frictionless case further.

Start the Energy Diagrams Explorer program.

Instructions:

1. With this program you can place a pair of magnets along the track and give the car a push. Click on the Add Magnets button and then click and drag the magnets to where you would like them.
2. You can also change the amount of friction --- a coefficient of friction equal to zero means no friction. You can vary the value of friction using the Friction Coefficient slider.
3. The kinetic energy diagram appears at the bottom of the screen in purple.
4. The total energy (red) and the potential energy (blue) diagrams appear in the center of the screen.
5. You can vary the initial energy of the car using the Initial Energy slider.

NB: The top graph shows a targeted potential energy in green. It is possible to import a potential energy file, which would be shown in green. Students would then use the simulation program to match the imported profile. We will not be using the targeted potential energy feature so feel free to ignore the top graph.

Set up a computer version of the repulsion experiment that you just completed. Try it with a small amount of friction and describe your results below.

Now, set the coefficient of friction to zero. How do the results change?

Repeat the process for the experiment in Tutorial 1 -- attraction. Describe your results below.

The potential energy diagrams can provide information about many details of the motion other than increasing or decreasing of the speed of the object. Now that you are familiar with the two basic arrangements of magnets and their corresponding energy diagrams, you can use this knowledge to explore a new, more complex situation - motion restricted in a small region of space (a trap). In the next activity you will study the condition that allows the trapping and some other concepts such as turning points and binding energy associated with this type of motion.