Question

What causes a spring to bounce up when it is pushed down and then released?

Answer 1

(a) Pushing the spring down gives it stored mechanical energy that turns into motion

Explanation:

Pushing on the spring causes the mechanical energy, of pushing on the spring, to be stored in the spring through potential elastic energy. Due to the elasticity of the spring, when the spring is released and resumes its initial shape the stored energy is released and can be used to do work such as motion.