Type one to two paragraphs describing the changes in potential and kinetic energy of the cart. Be sure to discuss how the potential and kinetic energy of the cart changes at each of the four
positions along the track, and explain why these changes occur.

Cart A starts out on the top of the hill, it has great potential energy, low kinetic energy, and some thermal energy. Cart B is going down the hill which increased the kinetic energy and the thermal energy while the potential energy is decreasing. Cart C is at the bottom of the hill, having high kinetic energy, low potential energy and some thermal energy. Cart D is at the top of a smaller hill, giving it high potential energy, low kinetic energy and little thermal energy.

These changes occur because when an object is at a high place, it will have high potential energy, and low kinetic energy, and as the height goes down, the kinetic energy increases and the potential energy will decrease.  

Explanation:

here's my version of answer

b.a device that inputs heat into a cool object