Joule

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Joule

The joule is the derived unit

SI derived unit

SI derived units are part of the SI system of measurement Units of measurements and are derived from the seven SI base units.Note that while the names of all SI units are in lowercase, the symbols of units named after people are written with an initial capital letter ....
of energy

Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
in the International System of Units

International System of Units

The International System of Units is the modern form of the metric system and is generally a system devised around the convenience of the number ten....
. It is defined as:

One joule is the amount of energy required to perform the following actions:

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What energy in Joules corresponds to 657nm??

Encyclopedia

The joule is the derived unit

SI derived unit

Energy

International System of Units

The work done by a force of one newton
Newton

The newton is the International System of Units SI derived unit of force, named after Isaac Newton in recognition of his work on classical mechanics....
traveling through a distance of one meter;
The work required to move an electric charge
Electric charge

Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields....
of one coulomb
Coulomb

The coulomb is the SI unit of electric charge. It is named after Charles-Augustin de Coulomb....
through an electrical potential
Electric potential

At a point in space, the electric potential is the potential energy per unit of electric charge that is associated with a static electric field....
difference of one volt
Volt

The volt is the SI SI derived unit of electric potential difference or electromotive force, commonly known as voltage. It is named in honor of the Lombard physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery ....
; or one coulomb volt, with the symbol C·V;
The work done to produce the power
Power (physics)

In physics, power is the rate at which mechanical work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time....
of one watt
WATT

WATT is a radio station broadcasting a News radio-Talk radio-Sports radio format. Licensed to Cadillac, Michigan, it first began broadcasting in 1945....
continuously for one second
Second

The second , sometimes abbreviated sec., is the name of a units of measurement of time, and is the International System of Units SI base unit of time....
; or one watt second (compare kilowatt hour), with the symbol W·s. Thus a kilowatt hour is 3,600,000 joules or 3.6 megajoules;
The kinetic energy
Kinetic energy

The kinetic energy of an object is the extra energy which it possesses due to its motion. It is defined as the mechanical work needed to accelerate a body of a given mass from rest to its current velocity....
of a 2 kilogram
Kilogram

The kilogram or kilogrammeThe spelling kilogram is used by the International Committee for Weights and Measures and the U.S....
(kg) mass
Mass

In physical science, mass refers to the degree of acceleration a body acquires when subject to a force: bodies with greater mass are accelerated less by the same force....
(m) moving at a velocity
Velocity

In physics, velocity is defined as the Derivative of Position vector. It is a vector physical quantity; both speed and direction are required to define it....
of 1 meter per second (m/s). The energy is linear
Linear

The word linear comes from the Latin word linearis, which means created by lines.In mathematics, a linear map or function f is a function which satisfies the following two properties......
in the mass but quadratic
Quadratic

In mathematics, the term quadratic describes something that pertains to Square , to the operation of squaring, to terms of the second degree of a polynomial, or equations or formulas that involve such terms....
in the velocity, being given by E = ½mv², energy (E) is equal to 1/2 of mass (m) multiplied
Multiplication

Multiplication is the Operation of scaling one number by another. It is one of the four basic operations in elementary arithmetic .Multiplication is defined for Natural number in terms of repeated addition; for example, 4 multiplied by 3 can be calculated by adding 3 copies of 4 together:...
by velocity (v) squared
Square (algebra)

In algebra, the square of a number is that number multiplication by itself. To square a quantity is to multiply it by itself.Its notation is a superscripted "2"; a number x squared is written as x?....
.

Conversions

1 joule is exactly 10⁷ erg

Erg

An erg is the unit of energy and mechanical work in the Centimetre gram second system of units system of Units of measurements, symbol "erg"....
s.

1 joule is exactly equal to:

6.2415 eV (electronvolt
Electronvolt

In physics, the electron volt is a unit of energy. By definition, it is equal to the amount of kinetic energy gained by a single unbound electron when it accelerates through an Electrostatics potential difference of one volt....
s)
0.2390 cal (calorie
Calorie

The calorie is a pre-SI metric system unit of energy. The unit was first defined by Professor Nicolas Cl?ment in 1824 as a unit of heat. This definition entered French and English dictionaries between 1841 and 1867....
) (small calories, lower case c)
2.3901 kilocalorie, Calories (food energy, upper case C)
9.4782 BTU (British thermal unit
British thermal unit

The British thermal unit is a unit of energy used in the power, steam generation, heating and air conditioning industries. In scientific contexts the BTU has largely been replaced by the SI unit of energy, the joule , though it may be used as a measure of agricultural energy production ....
)
0.7376 ft·lbf (foot-pound force
Foot-pound force

The foot-pound force, or simply foot-pound is a unit of Mechanical work or energy and also a unit of torque ....
)
23.7 ft·pdl (foot poundal
Poundal

The poundal is a non-SI Units of measurement of force. It is a part of the foot-pound-second system of units, a coherent subsystem of English units introduced in 1879, and one of several specialized subsystems of mechanical units used as aids in calculations....
s)
2.7778 kilowatt hour
2.7778 watt hour
9.8692 litre
Litre

The litre or liter is a unit of volume. There are two official symbols: the Latin letter L in lower and upper case . The lower case L is often written as a cursive l to avoid confusion with the number 1 in antiqua fonts....
-atmosphere
Atmosphere (unit)

The standard atmosphere is an international reference pressure defined as 101,325 Pascal and formerly used as unit of pressure . For practical purposes it has been replaced by the Bar which is 100,000 Pa....

Units defined in terms of the joule include:

1 thermochemical calorie
Calorie

The calorie is a pre-SI metric system unit of energy. The unit was first defined by Professor Nicolas Cl?ment in 1824 as a unit of heat. This definition entered French and English dictionaries between 1841 and 1867....
= 4.184 J
1 International Table calorie = 4.1868 J
1 watt hour = 3600 J
1 kilowatt hour = 3.6 J (or 3.6 MJ)
1 ton TNT exploding = 4.184 GJ

Useful to remember:

1 joule = 1 newton meter = 1 watt second

Practical examples

One joule in everyday life is approximately:

the energy required to lift a small apple one meter straight up.
the energy released when that same apple falls one meter to the ground.
the energy released as heat
Heat

In physics and thermodynamics, heat is any transfer of energy from one body or thermodynamic system to another due to a difference in temperature....
by a quiet person, every hundredth of a second.
the energy required to heat one gram of dry, cool air
Earth's atmosphere

The Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by the Earth's gravity. Dry air contains roughly 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% Carbon dioxide in the Earth's atmosphere, and trace amounts of other gases....
by 1 degree Celsius
Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
.
one hundredth of the energy a person can receive by drinking a drop of beer
Beer

Beer is the world's oldest and most widely consumed alcoholic beverage and the third most popular drink overall after water and tea. It is produced by the brewing and Fermentation of starches, mainly derived from cereal?the most common of which is malted barley, although wheat, maize , and rice are widely used....
.
the kinetic energy of an adult human moving a distance of about a handspan every second.

Joule

Conversions

Practical examples

SI multiples

See also

External links