A body is oscillating up and down at the end of a spring. Let's consider when the body is at the top of its up-and-down motion.
The net force points downward.

Question

A body is oscillating up and down at the end of a spring. Let's consider when the body is at the top of its up-and-down motion. 
The net force points downward.

Quizplus · Accepted Answer

At the top of its up-and-down motion, the body is at its highest point and has the maximum potential energy. The spring is stretched to its maximum length and is pulling the body downwards with a force equal to its weight, so the net force on the body points downward.

A Body Is Oscillating Up and Down at the End