Kinetic energy vs. Potential energy
Energy is the ability to do work. Objects can have stored, or potential, energy when work has been done (such as raising an object in the air) or by virtue of their position (such as sitting at the top of a hill). Potential energy changes to kinetic energy when the object moves. Examples include holding a stretched spring (potential energy) and then releasing it (kinetic energy) or holding a box above the ground (potential energy) and then dropping it (kinetic energy).
Kinetic energy is a form of energy that results from an object's motion. There are many types of motion that use kinetic energy: translation (moving from one place to another), rotation, and vibration. The measurement of kinetic energy in an object is calculated based on the object's mass and velocity. It is measured in Joules.
Potential energy is a form of energy that results from an object's position or arrangement of parts. It is stored energy that can become kinetic energy. It includes potential electrical, chemical, and nuclear energy. The measurement of potential energy in an object is calculated based on the object's mass and its height or distance. It is measured in Joules.