Joule

For the physicist named James Prescott Joule, see James Prescott Joule. James Prescott Joule FRS (ˈdʒuːl December 24, 1818 &ndash October 11, 1889) was an English Physicist

The joule (pronounced /ˈdʒuːl/ or /ˈdʒaʊl/) (symbol: J) is the SI unit of energy measuring heat, electricity and mechanical work. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Joule heating is the process by which the passage of an Electric current through a conductor releases Heat. In Physics, mechanical work is the amount of Energy transferred by a Force. It was named after English physicist James Prescott Joule. James Prescott Joule FRS (ˈdʒuːl December 24, 1818 &ndash October 11, 1889) was an English Physicist

1 Description
2 History
3 Conversions
- 3.1 SI multiples
4 See also
5 References
6 External links

Description

One joule is the work done, or energy expended, by a force of one newton moving one metre along the direction of the force. In Physics, a force is whatever can cause an object with Mass to Accelerate. The newton (symbol N) is the SI derived unit of Force, named after Isaac Newton in recognition of his work on Classical The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International This quantity is also denoted as a newton metre with the symbol N·m. Newton metre is the unit of moment ( Torque) in the SI system Note that torque also has the same units as work, but the quantities are not the same. A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about In elementary units:

$\, 1\, \mathrm{J}=1\, \mathrm{N} \cdot \mathrm{m}$

$\, 1\, \mathrm{J}=1\, \mathrm{kg} \cdot \frac{\mathrm{m}^{2}}{\mathrm{s}^{2}}$

One joule is also:

The work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt, with the symbol C·V. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. The coulomb (symbol C) is the SI unit of Electric charge. It is named after Charles-Augustin de Coulomb. The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force.
The work done to produce power of one watt continuously for one second; or one watt second (compare kilowatt hour), with the symbol W·s. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units Thus a kilowatt hour is 3,600,000 joules or 3. 6 megajoules
The kinetic energy of a 2 kg mass moving at a velocity of 1 m/sec. The energy is linear in the mass but quadratic in the velocity, being given by E = ½mv².
The potential energy of a 1 kg mass at an elevation of 1 m above a reference point in a gravitational field of 1 m/s². Earth's gravity being 9. 81 m/s² at sea level, 1 kg at 1 m above the Earth's surface has a potential energy of 9. 8 joules relative to that surface. When dropped the potential energy gradually becomes kinetic energy, with the conversion being complete at the instant the mass passes the reference point. Whereas kinetic energy is relative to an inertial frame, in this case that of the earth, potential energy is relative to a position, in this case the Earth's surface.

History

A joule is the mechanical equivalent of heat meaning the number of units of work in which the unit of heat can perform. Its value was found by James Prescott Joule in experiments that showed the mechanical energy Joule's equivalent, and represented by the symbol J. James Prescott Joule FRS (ˈdʒuːl December 24, 1818 &ndash October 11, 1889) was an English Physicist The term was first introduced by Dr. Mayer of Heilbronn.

Conversions

Main article: Conversion of units#Energy, work, or heat

1 joule is exactly 10⁷ ergs. Conversion of units refers to conversion factors between different Units of measurement for the same Quantity. An erg is the unit of Energy and Mechanical work in the centimetre-gram-second (CGS system of units symbol "erg"

1 joule is approximately equal to:

6. 2415 ×10¹⁸ eV (electronvolts)
0. 2390 cal (calorie) (small calories, lower case c)
2. This article is about the unit of energy For its use in Nutrition and Food labelling regulations, see the article on Food energy. 3901 ×10⁻⁴ kilocalorie, Calories (food energy, upper case C)
9. 4782 ×10⁻⁴ BTU (British thermal unit)
0. 7376 ft·lbf (foot-pound force)
23. The foot-pound force, or simply foot-pound (symbol ft·lbf or ft·lb) is a unit of work or Energy (a scalar 7 ft·pdl (foot poundals)
2. The poundal is a non- SI unit of Force. It is a part of the Foot-pound-second system of units a coherent subsystem of English units introduced 7778 ×10⁻⁷ kilowatt hour
2. 7778 ×10⁻⁴ watt hour
9. 8692 ×10⁻³ litre-atmosphere

1 joule in everyday life is approximately:

the energy required to lift a small apple one metre straight up. The Standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of Pressure (symbol atm The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International
the energy released when that same apple falls one meter to the ground.
the amount of energy, as heat, that a quiet person generates every hundredth of a second. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature
the energy required to heat one gram of dry, cool air by 1 degree Celsius. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five
one hundredth of the energy a person can get by drinking a single drop of beer. Beer is the world's oldest and most widely consumed Alcoholic beverage and the third most popular drink overall after water and tea
the kinetic energy of an adult human moving a distance of about a handspan every second.

Units defined in terms of the joule include:

1 thermochemical calorie = 4. This article is about the unit of energy For its use in Nutrition and Food labelling regulations, see the article on Food energy. 184 J
1 International Table calorie = 4. 1868 J
1 watt hour = 3600 J
1 kilowatt hour = 3. 6 ×10⁶ J (or 3. 6 MJ)
1 ton TNT = 4. 184 GJ

Useful to remember:

1 joule = 1 newton metre = 1 watt second

SI multiples

SI multiples for joule (J)

Submultiples			Multiples
Value	Symbol	Name	Value	Symbol	Name
10^–1 J	dJ	decijoule	10¹ J	daJ	decajoule
10^–2 J	cJ	centijoule	10² J	hJ	hectojoule
10^–3 J	mJ	millijoule	10³ J	kJ	kilojoule
10^–6 J	µJ	microjoule	10⁶ J	MJ	megajoule
10^–9 J	nJ	nanojoule	10⁹ J	GJ	gigajoule
10^–12 J	pJ	picojoule	10¹² J	TJ	terajoule
10^–15 J	fJ	femtojoule	10¹⁵ J	PJ	petajoule
10^–18 J	aJ	attojoule	10¹⁸ J	EJ	exajoule
10^–21 J	zJ	zeptojoule	10²¹ J	ZJ	zettajoule
10^–24 J	yJ	yoctojoule	10²⁴ J	YJ	yottajoule
Common multiples are in bold face

This SI unit is named after James Prescott Joule. James Prescott Joule FRS (ˈdʒuːl December 24, 1818 &ndash October 11, 1889) was an English Physicist As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (J). The musical instrument is spelled Cymbal. A symbol is something --- such as an object, Picture, written word a sound a piece Capital letters or majuscules pronunciation /məˈdʒʌskyuls ˈmædʒəˌskyuls/ in the Roman alphabet A, B, C, D, When an SI unit is spelled out in English, it should always begin with a lowercase letter (joule), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Lower case (also lower-case or lowercase) minuscule, or small letters are the smaller form of letters as opposed to upper Note that "degree Celsius" conforms to this rule because the "d" is lowercase. The Celsius Temperature scale was previously known as the centigrade scale.

— Based on The International System of Units, section 5. 2.

References

The adoption of joules as units of energy, FAO/WHO Ad Hoc Committee of Experts on Energy and Protein, 1971. Conversion of units refers to conversion factors between different Units of measurement for the same Quantity. An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol to form a Decimal multiple or An order of magnitude is the class of scale or magnitude of any amount where each class contains values of a fixed ratio to the class preceding it This list compares various energies in Joules (J organized by Order of magnitude. In Physics, fluence or integrated Flux is defined as the number of particles that intersect a unit area. A foe is a unit of Energy equal to 1044 Joules or 1051 Ergs used to measure the large amount of energy produced by a Supernova A report on the changeover from calories to joules in nutrition. This article is about the unit of energy For its use in Nutrition and Food labelling regulations, see the article on Food energy.

External links

Dictionary

-noun

In the International System of Units, the derived unit of energy, work and heat; the work required to exert a force of one newton for a distance of one metre. Also equal to the energy of one watt of power for a duration of one second. Symbol: J

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