The diagram shows a ball resting at the top of a hill.
Which statement best describes the energy in this system?
A) The potential energy in the system is greatest at X.
B) The kinetic energy in the system is greatest at X.
C) Total energy in the system decreases as the ball moves from X to Y.
D) Total energy in the system increases as the ball moves from X to Y.

a) The potential energy in the system is greatest at X.

Explanation:

Let be X the point where a ball rests at the top of a hill. By applying the Principle of Energy Conservation, the total energy in the physical system remains constant and gravitational potential energy at the top of the hill is equal to the sum of kinetic energy, a lower gravitational energy and dissipated work due to nonconservative forces (friction, dragging).

Conclusions are showed as follows:

a) The potential energy in the system is greatest at X.

b) The kinetic energy is the lowest at X and Z.

c) Total energy remains constant as the ball moves from X to Y.

Hence, the correct answer is A.