Question

A ball, starting from rest at Position 1, rolls along a curved track toward Position 5. The ball speeds up as it rolls from Position 1 to Position 3, and it slows down as it rolls from Position 3 toward Position 5. Just before it reaches Position 5, it stops and rolls back down the track. As the ball rolls back and forth along the curved track, the ball and the track get a little warmer.When does the Thermal energy of the ball and track increase and why?

Answer 1

From the law of conservation of energy, the energy can neither be created nor be destroyed. But it can be converted from one form to another.

At position 3, the ball will have maximum kinetic energy and at 1 and 3 the ball has the energy only in the form of gravitational potential energy.

The potential energy and kinetic energy of the ball will be lost due to the friction between the ball and the track. This lost energy will be converted into thermal energy. The friction will act on the ball throughout its motion on the track.

Thus, the thermal energy increases the entire time the ball rolls on the track. And both gravitational potential energy and kinetic energy are converted into thermal energy.

Therefore, the correct answer is option C.