AskDefine | Define kilojoule

User Contributed Dictionary



From kilo + joule


  1. One thousand ( 103 ) joules. Symbol: kJ or KJ.

Extensive Definition

The joule ( or /ˈdʒaʊl/) (symbol: J) is the SI unit of energy measuring heat, electricity and mechanical work. It was named after English physicist James Prescott Joule.


One joule is the work done, or energy expended, by a force of one newton moving one metre along the direction of the force. This quantity is also denoted as a newton metre with the symbol N·m. Note that torque also has the same units as work, but the quantities are not the same. In elementary units:
\, 1\, \mathrm=1\, \mathrm \cdot \mathrm
\, 1\, \mathrm=1\, \mathrm \cdot \frac
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.
  • 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. Thus a kilowatt hour is 3,600,000 joules or 3.6 megajoules


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. The term was first introduced by Dr. Mayer of Heilbronn.


1 joule is exactly 107 ergs.
1 joule is approximately equal to:
1 joule in everyday life is approximately:
  • the energy required to lift a small apple one metre straight up.
  • 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.
  • the energy required to heat one gram of dry, cool air by 1 degree Celsius.
  • one hundredth of the energy a person can get by drinking a single drop of beer.
  • 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 = 4.184 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 = 4.184 GJ
Useful to remember:
  • 1 joule = 1 newton metre = 1 watt second

SI multiples

See also


kilojoule in Afrikaans: Joule
kilojoule in Arabic: جول
kilojoule in Asturian: Xuliu (unidá)
kilojoule in Bengali: জুল
kilojoule in Belarusian: Джоўль
kilojoule in Belarusian (Tarashkevitsa): Джоўль
kilojoule in Bosnian: Džul
kilojoule in Bulgarian: Джаул
kilojoule in Catalan: Joule
kilojoule in Czech: Joule
kilojoule in Danish: Joule
kilojoule in German: Joule
kilojoule in Estonian: Džaul
kilojoule in Modern Greek (1453-): Τζάουλ (μονάδα μέτρησης)
kilojoule in Spanish: Julio (unidad)
kilojoule in Esperanto: Ĵulo
kilojoule in Basque: Joule (unitatea)
kilojoule in Persian: ژول
kilojoule in French: Joule
kilojoule in Scottish Gaelic: Joule
kilojoule in Galician: Joule (unidade)
kilojoule in Korean: 줄 (단위)
kilojoule in Croatian: Džul
kilojoule in Indonesian: Joule
kilojoule in Icelandic: Júl
kilojoule in Italian: Joule
kilojoule in Hebrew: ג'ול
kilojoule in Swahili (macrolanguage): Jouli
kilojoule in Latin: Joulium
kilojoule in Latvian: Džouls
kilojoule in Lithuanian: Džaulis
kilojoule in Hungarian: Joule
kilojoule in Malay (macrolanguage): Joule
kilojoule in Dutch: Joule
kilojoule in Japanese: ジュール
kilojoule in Norwegian: Joule
kilojoule in Norwegian Nynorsk: Joule
kilojoule in Occitan (post 1500): Joule
kilojoule in Polish: Dżul
kilojoule in Portuguese: Joule
kilojoule in Kölsch: Joule (Mohß)
kilojoule in Romanian: Joule
kilojoule in Russian: Джоуль
kilojoule in Simple English: Joule
kilojoule in Slovak: Joule
kilojoule in Slovenian: Džul
kilojoule in Serbian: Џул
kilojoule in Finnish: Joule
kilojoule in Swedish: Joule
kilojoule in Thai: จูล
kilojoule in Vietnamese: Joule
kilojoule in Turkish: Joule (birim)
kilojoule in Ukrainian: Джоуль
kilojoule in Urdu: جاؤل
kilojoule in Venetian: Joule
kilojoule in Chinese: 焦耳
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