Energy is defined as the ability to do work. There are many different forms of energy. According to the law of conservation of energy, energy may convert to other forms, but is never created or destroyed. Here is a list of 10 common types of energy and examples of each of them. Any object may possess multiple types of energy.
Kinetic energy is energy of motion. It ranges from zero to a positive value.
Example: An example of kinetic energy is a child swinging on a swing. At the top of the swing’s arc, the kinetic energy is zero. No matter whether the child is swinging forward or backward, the kinetic energy is always zero or positive.
Kinetic energy is often discussed with potential energy because these two forms of energy readily convert between each other. Potential energy is energy of an object’s position.
Examples: A classic example of potential energy is an apple resting on a table. The potential energy of the apple is zero with respect to the table, but positive with respect to the floor on which the table rests. In the case of a swinging child, potential energy is at its maximum when the swing is highest and at its minimum (zero) when the swing is closest to the ground.
Mechanical energy is the sum of the kinetic and potential energy of a system. It is the energy resulting from the movement or physical location of an object. Either the kinetic or potential energy may be zero at any given time.
Example: A car driving up and down a hill has both kinetic and potential energy. The car gains potential energy as it nears the top of the hill. Unless the brakes are applied, it gains kinetic energy as it goes down the hill.
Nuclear energy is the energy of the atomic nucleus. It may be released by nuclear reactions or other changes in the nucleus.
Examples: Radioactive decay, nuclear fission, and nuclear fusion are examples of nuclear energy. Other examples include nuclear power and energy released by an atomic explosion.
Just as the atomic nucleus has energy, so do the electrons orbiting the nucleus. Ionization energy is the energy the binds electrons to a molecule, atom, or ion.
Example: The first ionization energy is the energy required to remove one electron completely. The second ionization energy is the energy required to remove a second electron. It is always greater than the first ionization energy.
Chemical energy is energy released or absorbed by chemical reactions between atoms and molecules. Like ionization energy, it is an energy associated with electrons. Chemical energy may be divided into additional categories of energy, including chemiluminescence and electrochemical energy.
Examples: A glowstick releases light from a chemical reaction. A battery generates electrical energy from a chemical reaction.
Electromagnetic energy is also called radiant energy. It is energy from light, magnetism, or electromagnetic radiation.
Examples: Any portion of the electromagnetic spectrum has energy, including radio, microwaves, visible light, x-rays, gamma radiation, and ultraviolet light. Similarly, magnets produce an electromagnetic field and have energy.
Thermal energy is energy associated with heat. It is a type of electromagnetic energy. Thermal energy reflects the temperature difference between two systems.
Example: A cup of hot coffee has thermal energy. It releases heat to the environment.
Sonic energy is energy associated with sound waves. Sound waves travel through air or any other medium.
Examples: Examples of sonic energy include a sonic boom, your voice, or a song.
Gravitational energy is the attractive energy between objects based on their mass. Often, it serves as a basis for mechanical energy, as objects have potential energy with respect to one another and may move closer to each other.
Examples: The gravitational energy between the Earth and Moon produces the Moon’s orbit. Gravitational energy holds the atmosphere to the Earth.
- Harper, Douglas. “Energy”. Online Etymology Dictionary.
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- Smith, Crosbie (1998). The Science of Energy – a Cultural History of Energy Physics in Victorian Britain. The University of Chicago Press. ISBN 978-0-226-76420-7.