Potential Energy Definition (U)

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

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

Potential Energy Examples

A ball resting on top of a table has potential energy. This is called gravitational potential energy because its energy the object gains from its vertical position. 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, as electrons can move 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

Which leads to the equation for elastic potential energy:

PE = 0.5kx2

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Helmenstine, Anne Marie, Ph.D. "Potential Energy Definition (U)." ThoughtCo, Apr. 17, 2018, thoughtco.com/definition-of-potential-energy-604611. Helmenstine, Anne Marie, Ph.D. (2018, April 17). Potential Energy Definition (U). Retrieved from https://www.thoughtco.com/definition-of-potential-energy-604611 Helmenstine, Anne Marie, Ph.D. "Potential Energy Definition (U)." ThoughtCo. https://www.thoughtco.com/definition-of-potential-energy-604611 (accessed May 25, 2018).