Erg

Template:Short description Template:Hatnote group Template:Use Oxford spelling Template:Infobox unit The erg is a unit of energy equal to 10⁻⁷Template:Nbspjoules (100Template:NbspnJ). It is not an SI unit, instead originating from the centimetre–gram–second system of units (CGS). Its name is derived from Template:Transliteration ({{#invoke:Lang|lang}}), a Greek word meaning 'work' or 'task'.<ref>Template:Cite book</ref>

An erg is the amount of work done by a force of one dyne exerted for a distance of one centimetre. In the CGS base units, it is equal to one gram centimetre-squared per second-squared (g⋅cm²/s²). It is thus equal to 10⁻⁷ joules or 100 nanojoules (nJ) in SI units.

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• 1 erg = Template:Val = Template:Val
• 1 erg = Template:Val = Template:Val
• 1 erg = Template:Cvt

History

In 1864, Rudolf Clausius proposed the Greek word {{#invoke:Lang|lang}} (Template:Transliteration) for the unit of energy, work and heat.<ref name="Clausius_1867"/><ref name="Howard_2002"/> In 1873, a committee of the British Association for the Advancement of Science, including British physicists James Clerk Maxwell and William Thomson recommended the general adoption of the centimetre, the gramme, and the second as fundamental units (C.G.S. System of Units). To distinguish derived units, they recommended using the prefix "C.G.S. unit of ..." and requested that the word erg or ergon be strictly limited to refer to the C.G.S. unit of energy.<ref name="BSAS_1873"/>

In 1922, chemist William Draper Harkins proposed the name micri-erg as a convenient unit to measure the surface energy of molecules<ref name="Jerrard_2012"/> in surface chemistry.<ref name="Cardarelli_1966"/><ref name="Cardarelli_2003"/> It would equate to 10⁻¹⁴ erg,<ref name="Jerrard_2012"/><ref name="Harkins_1922"/><ref name="Colloid_1925"/><ref name="ACh_1922"/><ref name="Partington_1949"/> the equivalent to 10⁻²¹ joule.

The erg is not a part of the International System of Units (SI), which has been recommended since 1 January 1978<ref>Template:Cite book</ref> when the European Economic Community ratified a directive of 1971 that implemented SI as agreed by the General Conference of Weights and Measures.<ref>Template:Cite journal</ref> It is the unit of energy in Gaussian units, which are widely used in astrophysics<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>Template:Better source needed, applications involving microscopic problems and relativistic electrodynamics,<ref>Template:Cite book</ref> and sometimes in mechanicsTemplate:Citation needed.

See also

• Foe (unit), relative measure for energy released by a supernova
• Lumen second, for the lumerg and lumberg units
• Metre–tonne–second system of units

References

<references> <ref name="ACh_1922">Template:Cite journal</ref> <ref name="Colloid_1925">Template:Cite book</ref> <ref name="Cardarelli_2003">Template:Cite book</ref> <ref name="Jerrard_2012">Template:Cite book</ref> <ref name="Cardarelli_1966">Template:Cite book</ref> <ref name="Harkins_1922">Template:Cite book</ref> <ref name="Partington_1949">Template:Cite book</ref>

<ref name="Clausius_1867">Template:Cite book </ref> <ref name="Howard_2002">Template:Cite journal </ref> <ref name="BSAS_1873">Template:Cite conference</ref> </references>