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 acceleration is zero.

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 acceleration is zero.

Quizplus · Accepted Answer

When the body is at the top of its up-and-down motion, it is momentarily changing direction, which means it is accelerating towards the equilibrium position due to the restoring force of the spring.

A Body Is Oscillating Up and Down at the End