Potential Energy
Potential energy is the stored energy possessed by an object due to its position, configuration, or state relative to a reference point or field. Unlike kinetic energy (energy of motion), potential energy is latent and can be converted into kinetic or other forms of energy when the object moves or changes state. The most common forms in classical mechanics are gravitational potential energy and elastic potential energy.
Types of potential energy in physics
| Type | Depends On | Formula | Example |
|---|---|---|---|
| Gravitational | Height above reference level | U = mgh | Water behind a dam |
| Elastic | Compression/extension of spring | U = ½kx² | Compressed spring in a toy |
| Electric | Charge and electric potential | U = qV | Charged capacitor plates |
| Chemical | Molecular bond configuration | Complex (thermodynamic) | Petrol, food, batteries |
| Nuclear | Nuclear binding energy | E = mc² (binding) | Uranium fuel rods |
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Related Terms
Kinetic Energy
Kinetic energy is the energy possessed by an object due to its state of motion. It depends on both the mass of the object and the square of its speed, meaning that doubling the speed quadruples the kinetic energy. Kinetic energy is transferred to objects through work and is a key quantity in collision analysis, transport safety, and the work-energy theorem.
Gravitational Potential Energy
Gravitational potential energy (GPE) is the energy stored in an object due to its height above a chosen reference level in a gravitational field. It increases with both the mass of the object and its height above the reference, and is fully convertible to kinetic energy as the object falls. GPE is fundamental to the analysis of projectiles, hydroelectric power generation, and the orbital mechanics of satellites.
Conservation of Energy
The law of conservation of energy states that the total energy of an isolated system remains constant over time: energy can neither be created nor destroyed, only transformed from one form to another. In mechanical systems, this means the sum of kinetic energy and potential energy remains constant in the absence of non-conservative forces such as friction. This principle, one of the most fundamental in all of science, is derived mathematically from Noether's theorem as a consequence of the time-translation symmetry of physical laws.
The term "potential energy" was introduced by Scottish engineer William Rankine in 1853 in his paper "On the General Law of the Transformation of Energy". "Potential" comes from Latin "potentia" (power, capability), from "potens" (powerful, able). "Energy" derives from Greek "energeia" (operation, activity), coined by Aristotle.