# Energy

energy transferenergiestotal energyenergeticforms of energyenergy flowenergy useEnergy formphysical energy[energy
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.wikipedia
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### Physics

physicistphysicalphysicists
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
Physics (from, from φύσις phýsis 'nature') is the natural science that studies matter, its motion and behavior through space and time, and that studies the related entities of energy and force.

### Heat

heat energythermalhot
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
In thermodynamics, heat is energy in transfer to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter.

### Conservation of energy

law of conservation of energyenergyenergy conservation law
Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed.
In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time.

### Work (thermodynamics)

workthermodynamic workpressure-volume work
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
In thermodynamics, work performed by a system is energy transferred by the system to its surroundings, by a mechanism through which the system can spontaneously exert macroscopic forces on its surroundings, where those forces, and their external effects, can be measured.

### Joule

JkJMJ
The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
The joule ( symbol: J) is a derived unit of energy in the International System of Units.

### Potential energy

potentialpotential energiesgravitational potential
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature. It showed that the gravitational potential energy lost by the weight in descending was equal to the internal energy gained by the water through friction with the paddle.
In physics, potential energy is the energy held by an object because of its position relative to other objects, stresses within itself, its electric charge, or other factors.

### Kinetic energy

kinetickinetic energiesenergy
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.
In physics, the kinetic energy (KE) of an object is the energy that it possesses due to its motion.

### Energy industry

energyenergy sectorenergy company
Human civilization requires energy to function, which it gets from energy resources such as fossil fuels, nuclear fuel, or renewable energy.
The energy industry is the totality of all of the industries involved in the production and sale of energy, including fuel extraction, manufacturing, refining and distribution.

### Ecosystem

ecosystemsenvironmenteco-system
The processes of Earth's climate and ecosystem are driven by the radiant energy Earth receives from the sun and the geothermal energy contained within the earth.
By feeding on plants and on one-another, animals play an important role in the movement of matter and energy through the system.

### Chemical energy

chemicalenergychemical energies
Common forms of energy include the kinetic energy of a moving object, the potential energy stored by an object's position in a force field (gravitational, electric or magnetic), the elastic energy stored by stretching solid objects, the chemical energy released when a fuel burns, the radiant energy carried by light, and the thermal energy due to an object's temperature.
Examples include batteries, food, gasoline, and etc. Breaking or making of chemical bonds involves energy, which may be either absorbed or evolved from a chemical system.

### Mass

inertial massgravitational massweight
Mass and energy are closely related.
Because the total energy must be real, the numerator must also be imaginary: i.e. the rest mass m must be imaginary, as a pure imaginary number divided by another pure imaginary number is a real number.

### International System of Units

SISI unitsSI unit
The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
The principle of coherence was successfully used to define a number of units of measure based on the CGS, including the erg for energy, the dyne for force, the barye for pressure, the poise for dynamic viscosity and the stokes for kinematic viscosity.

### Mechanical energy

mechanicalconservation of mechanical energyenergy
For example, macroscopic mechanical energy is the sum of translational and rotational kinetic and potential energy in a system neglects the kinetic energy due to temperature, and nuclear energy which combines utilize potentials from the nuclear force and the weak force), among others.
It is the energy associated with the motion and position of an object.

### Force

forcesattractiveelastic force
The SI unit of energy is the joule, which is the energy transferred to an object by the work of moving it a distance of 1 metre against a force of 1 newton.
In the special theory of relativity, mass and energy are equivalent (as can be seen by calculating the work required to accelerate an object).

### Thermodynamics

thermodynamicthermodynamicallyclassical thermodynamics
These developments led to the theory of conservation of energy, formalized largely by William Thomson (Lord Kelvin) as the field of thermodynamics.
Thermodynamics is the branch of physics that deals with heat and temperature, and their relation to energy, work, radiation, and properties of matter.

### James Prescott Joule

James JouleJouleJ. P. Joule
In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat.
Joule studied the nature of heat, and discovered its relationship to mechanical work (see energy).

### Internal energy

specific internal energyenergyheat energy
It showed that the gravitational potential energy lost by the weight in descending was equal to the internal energy gained by the water through friction with the paddle.
In thermodynamics, the internal energy of a system is the energy contained within the system.

### Entropy

entropicentropicallyspecific entropy
It also led to a mathematical formulation of the concept of entropy by Clausius and to the introduction of laws of radiant energy by Jožef Stefan.
In other words, in any natural process there exists an inherent tendency towards the dissipation of useful energy.

### Kilowatt hour

kWhGWhTWh
However energy is also expressed in many other units not part of the SI, such as ergs, calories, British Thermal Units, kilowatt-hours and kilocalories, which require a conversion factor when expressed in SI units.
The kilowatt hour (symbol commonly kWh, officially but uncommon kW⋅h, kW h) is a unit of energy equal to 3.6 megajoules.

### Physical object

physical bodyobjectbody
In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.
In classical mechanics a physical body is collection of matter having properties including mass, velocity, momentum and energy.

### Noether's theorem

Noether currentNoether chargeNoether theorem
According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.
As another example, if a physical process exhibits the same outcomes regardless of place or time, then its Lagrangian is symmetric under continuous translations in space and time respectively: by Noether's theorem, these symmetries account for the conservation laws of linear momentum and energy within this system, respectively.

### Centimetre–gram–second system of units

CGScgs unitsCGS unit
The CGS energy unit is the erg and the imperial and US customary unit is the foot pound.
In measurements of purely mechanical systems (involving units of length, mass, force, energy, pressure, and so on), the differences between CGS and SI are straightforward and rather trivial; the unit-conversion factors are all powers of 10 as 100 cm = 1 m and 1000 g = 1 kg.

### Josiah Willard Gibbs

Willard GibbsJ. Willard GibbsGibbs
Thermodynamics aided the rapid development of explanations of chemical processes by Rudolf Clausius, Josiah Willard Gibbs, and Walther Nernst.
That work, which covers about three hundred pages and contains exactly seven hundred numbered mathematical equations, begins with a quotation from Rudolf Clausius that expresses what would later be called the first and second laws of thermodynamics: "The energy of the world is constant. The entropy of the world tends towards a maximum."

### Biology

biologicalBiological Sciencesbiologist
In biology, energy is an attribute of all biological systems from the biosphere to the smallest living organism.
Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis.

### Metabolism

metabolicmetabolizedmetabolic pathways
In human terms, the human equivalent (H-e) (Human energy conversion) indicates, for a given amount of energy expenditure, the relative quantity of energy needed for human metabolism, assuming an average human energy expenditure of 12,500 kJ per day and a basal metabolic rate of 80 watts.
The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of nitrogenous wastes.