GC: n

CT: Physicists, who are scientists who study force, motion and energy, say that energy is the ability to do work, and work is moving something against a force, like gravity. There are a lot of different kinds of energy in the universe, and that energy can do different things.
Energy can be found in many things, and takes many forms. There is a kind of energy called kinetic energy in objects that are moving. There is something that scientists call potential energy in objects at rest that will make them move if resistance is removed.

S: http://www.qrg.northwestern.edu/projects/vss/docs/space-environment/1-what-is-energy.html(external link) (last access: 10 February 2015)

N: 1. 1590s, "force of expression," from Middle French énergie (16c.), from Late Latin energia, from Greek energeia "activity, action, operation," from energos "active, working," from en "at" + ergon "work, that which is wrought; business; action".
Used by Aristotle with a sense of "actuality, reality, existence" (opposed to "potential") but this was misunderstood in Late Latin and afterward as "force of expression," as the power which calls up realistic mental pictures. Broader meaning of "power" in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.
2. Energy is the capacity of a system to do work. That system may be a jet, carrying hundreds of passengers across the ocean. A baby’s body, growing bone cells. A kite, rising on the wind. Or a wave of light crossing a space.
In moving or growing, each of these systems is doing work, and using energy. Every living organism does work, and needs energy from food or photosynthesis. Humans also create machines that do work for them, and that derive energy from fuels.
3. Some of the many forms that energy takes are:
  • Mechanical energy, which includes: Potential energy (stored in a system) and Kinetic energy (from the movement of matter).
  • Radiant or solar energy, which comes from the light and warmth of the sun.
  • Thermal energy, associated with the heat of an object.
  • Chemical energy, stored in the chemical bonds of molecules.
  • Electrical energy, associated with the movement of electrons.
  • Electromagnetic energy, associated with light waves (including radio waves, microwaves, x-rays, infrared waves).
  • Mass (or nuclear) energy, found in the nuclear structure of atoms.
4. Differences between "energy" and "power":
In physics, energy is defined as the amount of work that can be performed by force, whereas power is defined as the rate at which work is performed.
  • Energy is the capacity to do work. Energy is power integrated over time.
Unit: joules = watt-seconds.
Common symbol: W.
  • Power is the rate at which work is done, or energy is transmitted.
Unit: watt = joules/second.
Common symbol: P.
There are different forms of energy. These include kinetic, potential, thermal, gravitational, electromagnetic, sound, light and elastic. The form of energy is dependent on the frame of reference, and can be transformed into other forms. For instance potential energy is dependent on the position of the object, whereas kinetic energy is the energy required to accelerate an object to a particular speed, and so on.
Different forms of power could be electric power, which is the rate at which electrical energy is transferred by a circuit, human power, and optical power.
Transformation of energy: Various devices can be used to convert one form of energy into another. For instance, a battery converts chemical to electric energy, chemical explosion converts chemical energy in to kinetic and thermal energy and so on. Power cannot be converted or transformed.
5. Collocations: (energy) source of power.
  • Adj.: renewable | atomic, nuclear, solar, wave, wind.
  • Quant.: amount.
  • Verb + energy: generate, produce | harness | provide, supply | consume, use | store | conserve, save | waste | need, require.
  • Energy + noun: production | consumption, use | demand, needs, requirements | supply | resources, sources | conservation, savings | efficiency | bill, costs, prices | crisis, problem, shortage | company, industry, sector | market | management, plan, policy, programme, project, strategy.
  • Phrases: a demand for energy energy-saving | a form of energy, a source of energy.
S: 1. OED - http://www.etymonline.com/index.php?allowed_in_frame=0&search=energy&searchmode=none(external link) (last access: 18 December 2014). 2 & 3. http://www.api.org/oil-and-natural-gas-overview/classroom-tools/classroom-curricula/what-is-energy(external link) (last access: 10 February 2015). 4. http://www.diffen.com/difference/Energy_vs_Power(external link) (last access: 10 August 2015). 5. http://oxforddictionary.so8848.com/search?word=energy(external link) (last access: 20 May 2015).


CR: agroenergy, autotroph, bioconversion (EN), bioelectricity, biomass energy, chemical energy, energy label, energy poverty, energy source, kinetic energy, magnetic energy, mechanical energy, primary energy, radiant energy, sealing, thermodynamic cycle, unburned fuel.


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