# AP Physics 1 Question 136: Answer and Explanation

### Test Information

Question: 136

6. A children’s toy consists of a cart whose very light wheels are attached to a rubber band. This rubber band can wind and unwind around the axle supporting the wheels.

This toy is given a shove, after which the toy rolls across a flat surface and up a ramp. It is observed that the toy does not go a consistent distance up the ramp—in some trials it ends up higher than in other trials, even though the shove imparts the same kinetic energy to the cart each time. Which of the following is a reasonable explanation for this phenomenon?

• A. Depending on how the rubber band is initially wound, more or less potential energy can be transferred from the rubber band to the kinetic energy of the car’s motion.
• B. The normal force on the cart’s wheels will be different depending on how much the rubber band winds or unwinds.
• C. How much energy is transferred from kinetic energy to gravitational potential energy depends on the vertical height at which the cart ends up.
• D. Some of the cart’s initial kinetic energy will be dissipated due to work done by friction.