Potential energy is stored energy an object possesses due to its position, state, or composition. Unlike kinetic energy, which is the energy of motion, potential energy is associated with an object at rest, poised to release its stored energy. It is a property of a system, dependent on the relative arrangement of its parts.
Gravitational Energy
Gravitational potential energy is stored in an object based on its position within a gravitational field, typically its height above a chosen reference point. This energy is present because work is required to elevate an object against the force of gravity. For instance, a book placed on a high shelf, water held behind a dam, or a roller coaster at the peak of a hill all possess gravitational potential energy. The amount of this stored energy is influenced by three factors: the object’s mass, the acceleration due to gravity, and its vertical height.
Elastic Energy
Elastic potential energy is stored within a material when it is stretched, compressed, twisted, or otherwise deformed from its original resting state. This energy is held in the bonds between the atoms of the material as they are stressed. When the deforming force is removed, the material returns to its initial shape, releasing the stored energy. Common examples include the energy in a stretched rubber band, a compressed spring, a bent bow, or the springs of a trampoline when a person lands on it. The more an elastic object is deformed, the greater the elastic potential energy it stores.
Chemical Energy
Chemical potential energy is a form of potential energy stored within the chemical bonds that connect atoms and molecules. This energy is released or absorbed when chemical reactions occur, as these bonds are broken and new ones are formed. The rearrangement of electrons within atoms and molecules contributes to this stored energy. Everyday examples include the energy stored in food, which is released through metabolism in living organisms, and the energy in fuels like wood, coal, natural gas, and gasoline, which is released through combustion. Batteries also store chemical energy, converting it into electrical energy through chemical reactions.
Electrical and Magnetic Energy
Electrical potential energy is energy stored within an electric field, arising from the position of electric charges. It represents the work required to move a charge against an electric field. For example, a charged capacitor stores electrical potential energy, and the energy in a battery, while primarily chemical, is converted into electrical potential energy.
Magnetic potential energy is stored within a magnetic field, often linked to the arrangement of magnetic poles or the presence of current-carrying wires. This energy is associated with the interaction of magnetic dipoles within a magnetic field. Examples include the energy stored in an electromagnet or the forces of attraction and repulsion between two magnets.
Nuclear Energy
Nuclear potential energy is the immense energy contained within the nucleus of an atom, responsible for binding protons and neutrons together. This binding force is known as the strong nuclear force. This energy can be released during nuclear reactions, such as nuclear fission, where an atom’s nucleus is split, or nuclear fusion, where two lighter nuclei combine to form a heavier one. The processes involve a small amount of mass being converted into a large amount of energy, as described by Einstein’s famous equation. Nuclear power plants harness fission to generate electricity, and the sun produces energy through nuclear fusion.