A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance.
A)The total energy of the rock increases.
B)The kinetic energy increases and the potential energy decreases.
C)Both the potential energy and the total energy of the rock increase.
D)The kinetic energy decreases and the potential energy increases.
E)Both the kinetic energy and the potential energy of the rock remain the same.

Question

Quizplus · Accepted Answer

As the rock is thrown straight up, its velocity decreases until it reaches the highest point where it becomes momentarily stationary (disregarding air resistance). Therefore, the kinetic energy of the rock is converted into potential energy. As the rock then falls back down to the surface, the potential energy is converted back into kinetic energy. Hence, at the highest point, the kinetic energy is at its minimum and the potential energy is at its maximum. Therefore, the correct option is D, where the kinetic energy of the rock decreases and the potential energy increases.

A Rock Is Thrown Straight Up from the Surface of the Earth