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# Joule

This article has been reviewed by the following Topic Editor: Peter Saundry

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

### Definition

The joule (symbol: J) SI unit of work or energy, defined to be the work done by a force of one newton acting to move an object through a distance of one meter in the direction in which the force is applied. Equivalently, since kinetic energy is one half the mass times the square of the velocity, one joule is the kinetic energy of a mass of two kilograms moving at a velocity of 1 m/s. As a rough guide, 1 joule is the absolute minimum amount of energy required to lift a one kilogram object up by a height of 10 centimeters on the surface of the Earth.

### History

The unit is named for James Prescott Joule (1818-1889), the English physicist who made fundamental contributions to the study of heat and energy. Joule determined the mechanical equivalent of heat by measuring change in temperature produced by the friction of a paddlewheel attached to a falling weight in the 1840s.

### Conversions

from / to Joule kilowatt-hour electronvolt calorie Btu horsepower
hour
foot-pound dyne-
centimeter
therm
1 Joule 1 0.278 · 10?3 6.241 · 1018 0.2388 9.4782 · 10?4 3.7251 · 10-7 0.7376 1 · 107 9.4782 · 10?9
1 kilowatt-hour 3.6 · 106 1000 22.5 · 1024 8.5985 · 105 3.4121 · 103 1.3410 2.6552 · 106 3.6 · 1013 0.0341
1 electronvolt 0.1602 · 10?18 44.5 · 10?27 1 3.8267 · 10?20 1.5186 · 10?22 5.9682 · 10?26 1.1817 · 10?19 1.6022 · 10?12 1.5186 · 10?27
1 calorie 4.1868 1.163 · 10?3 0.261 · 1018 1 3.9683 · 10?3 1.56 · 10?6 3.0880 4.186 · 107 3.9683 · 10?8
1 Btu 1.055 · 103 0.293 6.585 · 1021 251.996 1 3.9302 · 10?4 778.169 1.05435 · 1010 1 · 10?5
1 horsepower-hour 2.6845 · 106 745.60 1.6755 · 1025 6.4119 · 105 2.5444 · 103 1 1.98 · 106 2.6845 · 1013 2.5444 · 10-2
1 foot-pound 1.3558 3.7662 · 10-4 8.4623 · 1018 0.3238 1.2851 · 10-3 5.0505 · 10-7 1 1.3558 · 107 1.2851 · 10-8
1 dyne-centimeter 1 · 10-7 2.7778 · 10-11 6.2415 · 1011 2.4 · 10-8 9.4782 · 10-11 3.7251 · 10-14 7.4 · 10-8 1 9.4782 · 10-16
1 therm 1.0551 · 108 2.9307 · 104 6.5851 · 1026 2.520 · 107 1 · 105 39.301 7.7817 · 107 1.0551 · 1015 1

## Citation

Cutler J. Cleveland (Lead Author);Peter Saundry (Topic Editor) "Joule". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth December 12, 2006; Last revised Date December 12, 2006; Retrieved May 21, 2013 <http://www.eoearth.org/article/Joule>

## The Author

Cutler J. Cleveland  is Professor of Earth and Environment at Boston University, where he also is on the faculty of the Center for Energy and Environmental Studies. Professor Cleveland is Editor-in-Chief of the Encyclopedia of Energy (Elsevier, 2004), winner of an American Library Association award, the Dictionary of Energy (Elsevier, 2005), Handbook of Energy (Elsevier, forthcoming), and is the Founding Editor-in-Chief of the Encyclopedia of Earth.  He is the recipient of the Adelma ... (Full Bio)