Potential Energy Definition and Formula

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Potential energy is energy that an object has because of its position relative to other objects. It is called potential because it has the potential to be converted into other forms of energy, such as kinetic energy. Potential energy is usually defined in equations by the capital letter U or sometimes by PE.

Potential energy may also refer to other forms of stored energy, such as energy from net electrical charge, chemical bonds, or internal stresses.

Examples of Potential Energy

A ball resting on top of a table has potential energy, called gravitational potential energy because it comes from the ball's position in the gravitational field. The more massive an object is, the greater its gravitational potential energy.

A drawn bow and a compressed spring also have potential energy. This is elastic potential energy, which results from stretching or compressing an object. For elastic materials, increasing the amount of stretch raises the amount of stored energy. Springs have energy when stretched or compressed.

Chemical bonds may also have potential energy, derived from electrons moving closer or further away from atoms. In an electrical system, potential energy is expressed as voltage.

Potential Energy Equations

If you lift a mass m by h meters, its potential energy will be mgh, where g is the acceleration due to gravity: PE = mgh.

For a spring, potential energy is calculated based on Hooke's Law, where the force is proportional to the length of stretch or compression (x) and the spring constant (k): F = kx.

Thus, the equation for elastic potential energy is PE = 0.5kx2