Total Energy and Potential Energy

Now on your "no friction" kinetic energy diagram, draw a line to represent the total of the car.

HINT: Far from the magnets, the total energy equals the kinetic energy of the car. When no friction or very low friction is present the total energy of the car is represented by a horizontal line.

You should get something like this:

The change in kinetic energy near the magnets shows that the kinetic energy becomes greater than the total energy. However, we know that energy is conserved. Thus, another form of energy must also change in the region near the magnets to keep the total energy constant. This other energy is the potential energy resulting from the magnetic interactions. We can use information about the kinetic and total energy of the car to construct a potential energy diagram of the car - magnet system. To construct a graph of a potential energy vs. distance, use potential energy = total energy - kinetic energy. In the present case we must just approximate because we do not have exact values.

Make a sketch of the potential energy diagram of the car by subtracting it from the kinetic energy diagram. Describe the sketch you made below: