Is Kinetic Energy Due to the Position of an Object?

Potential Energy

• Potential energy is a type of energy that can be measured when an object is not moving, while kinetic energy can only be measured for a moving object. For example, a ball held several feet above the ground has potential energy due to gravity. This can be calculated by multiplying the ball's mass by the force of gravity and the height above the ground. When it is released, that stored energy begins to convert to kinetic energy.

Potential to Kinetic

• As an object moves from its initial position, its potential energy changes to kinetic energy: the stored energy that related directly to the object's initial position is "released" in the form of kinetic energy. To use the example of a ball dropped from a few feet above the ground, when the ball is dropped, it begins to increase in velocity because of gravitational force, and this velocity can be used to determine the ball's kinetic energy as it drops.

Kinetic Energy and Position

• Although kinetic energy is not caused specifically by the position of an object, this does not mean that kinetic energy has no relation to position. On a roller coaster, for example, the velocity will change as the position of the rider shifts (as the roller coaster picks up speed downhill, for example). Since the measurement of kinetic energy depends on velocity at certain positions, a different velocity will translate into a different measure of kinetic energy.

Kinetic Energy and Observation

• Because kinetic energy depends on observation and perception, it is relative: while a stationary observer might view a train as possessing a great deal of kinetic energy at a given moment, an observer moving at the same speed as the train would not share this view. In this way of looking at kinetic energy, it does relate to position: observed kinetic energy depends on the position of the viewer in relation to the object.