Kinetic and Potential Energy

Core concept

The Law of Conservation of Energy states that energy cannot be created or destroyed, only converted from one form to another — a ball at the top of a hill has maximum potential energy and zero kinetic energy; as it rolls down, potential energy converts progressively into kinetic energy, reaching maximum kinetic energy (and zero potential energy relative to the bottom) just before it stops rolling. This interplay between kinetic and potential energy explains the motion of pendulums, roller coasters, and falling objects.