If the kinetic energy of the oscillating block on a spring is increasing, the block must be...?

Question

Consider a harmonic oscillator at four different moments, labeled A, B, C, and D, as shown in the figure http://session.masteringphysics.com/problemAsset/1003620/23/1003620.jpg .

Assume that the force constant k, the mass of the block, m, and the amplitude of vibrations, A, are given. Assume that there are no resistive forces; that is, E=constant.

Consider the block in the process of oscillating. If the kinetic energy of the block is increasing, the block must be

A: at the equilibrium position.

B: at the amplitude displacement.

C: moving to the right.

D: moving to the left.

E: moving away from equilibrium.

F: moving toward equilibrium.

Choose from A-F and explain why

Answer 1

The answer is F because the block has maximum kinetic energy at the point of equilibrium. Therefore, the closer the block is moving toward equilibrium, the more kinetic energy it is gaining and the more the kinetic energy of the system is increasing.