Erg

---

title: "Erg" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["units-of-energy", "centimetre–gram–second-system-of-units"] description: "CGS unit of energy and mechanical work" topic_path: "general/units-of-energy" source: "https://en.wikipedia.org/wiki/Erg" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary CGS unit of energy and mechanical work ::

::data[format=table title="Infobox unit"]

Field	Value
name	erg
standard	CGS units
quantity	energy
symbol	erg
extralabel	Derivation
extradata	1 erg = 1 dyn⋅cm
units1	CGS base units
inunits1	1 cm2⋅g⋅s−2
units2	SI units
inunits2
units3	British Gravitational System
inunits3	1 erg
::

| name = erg | image = | caption = | standard = CGS units | quantity = energy | symbol = erg | symbol2 = | extralabel = Derivation | extradata = 1 erg = 1 dyn⋅cm | units1 = CGS base units | inunits1 = 1 cm2⋅g⋅s−2 | units2 = SI units | inunits2 = | units3 = British Gravitational System | inunits3 = 1 erg The erg is a unit of energy equal to 10−7joules (100nJ). It is not an SI unit, instead originating from the centimetre–gram–second system of units (CGS). Its name is derived from grc (ἔργον), a Greek word meaning 'work' or 'task'.

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.

• 1 erg = =
• 1 erg = = =
• 1 erg = =
• 1 erg = =
• 1 erg = 1.000000 erg

History

In 1864, Rudolf Clausius proposed the Greek word ἐργον (grc) for the unit of energy, work and heat. 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.

In 1922, chemist William Draper Harkins proposed the name micri-erg as a convenient unit to measure the surface energy of molecules in surface chemistry. It would equate to 10−14 erg, 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 when the European Economic Community ratified a directive of 1971 that implemented SI as agreed by the General Conference of Weights and Measures. It is the unit of energy in Gaussian units, which are widely used in astrophysics, applications involving microscopic problems and relativistic electrodynamics, and sometimes in mechanics.

References

Not in use--

|url= https://www.biodiversitylibrary.org/item/94452#page/324/mode/1up |title=First Report of the Committee for the Selection and Nomenclature of Dynamical and Electrical Units |date=September 1873 |conference= Forty-third Meeting of the British Association for the Advancement of Science |editor-first= Professor |editor-last = Everett |editor-link = Joseph David Everett |first1 = Sir W |last1 = Thomson |author1-link = William Thomson, 1st Baron Kelvin |first2 = Professor GC |last2 = Foster |author2-link = Carey Foster |first3 = Professor JC |last3 = Maxwell |author3-link = James Clerk Maxwell |first4 = Mr GJ |last4 = Stoney |author4-link = George Johnstone Stoney |first5 = Professor Fleeming |last5 = Jenkin |author5-link = Fleeming Jenkin |first6 = Dr |last6 = Siemens |author6-link = Carl Wilhelm Siemens |first7 = Mr FJ |last7 = Bramwell |author7-link = Frederick Bramwell |publisher= John Murray |location= Bradford |page = 224 |access-date= 2014-03-17}}

References

1. Goodell, Thomas Dwight. (1889). "The Greek in English". [[Henry Holt and Company]].
2. (2012-03-26). "Architects' Data". John Wiley & Sons.
3. Jennings, W. A.. (October 1972). "SI units in radiation measurement". The British Journal of Radiology.
4. (2016-02-12). "Are ergs commonly used in astrophysics? If so, is there a specific reason for it?".
5. (2009). "Classical electrodynamics". Wiley.
6. (1922). "Journal of the American Chemical Society - Issues for 1898-1901 include Review of American chemical research, v. 4-7; 1879-1937, the society's Proceedings". [[American Chemical Society]].
7. Holmes, Harry N.. (1925). "Colloid Symposium Monograph - Papers Presented at the Second National Symposium on Colloid Chemistry, Northwestern University, June, 1924". The Chemical Catalog Company, Inc..
8. Cardarelli, François. (2003). "Encyclopaedia of Scientific Units, Weights and Measures". [[Springer-Verlag London Ltd.]].
9. (1993). "A Dictionary of Scientific Units - Including dimensionless numbers and scales". Chapman and Hall.
10. Cardarelli, François. (1999). "Scientific unit conversion: A practical guide to metrication". [[Springer-Verlag London Limited]].
11. (2013-07-01). "The Orientation of Molecules in Surfaces, Surface Energy, Adsorption, and Surface Catalysis. V. The Adhesional Work Between Organic Liquids and Water: Vaporization in Steps as Related to Surface Formation". University of Chicago.
12. Partington, James Riddick. (2010-02-17). "An Advanced Treatise on Physical Chemistry: Fundamental principles. The properties of gases". Longmans, Green.
13. Filippenko, Alex, ''Understanding the Universe'' (of ''The Great Courses'', on DVD), Lecture 44, time 24:30, The Teaching Company, Chantilly, VA, USA, 2007

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::