CGS unit of energy and mechanical work
Theerg is a unit of energy equal to 10−7 joules (100 n J). It is not anSI unit , instead originating from thecentimetre–gram–second system of units (CGS). Its name is derived fromergon ἔργον Greek word meaning 'work' or 'task'.[ 1]
An erg is the amount of work done by a force of onedyne exerted for a distance of onecentimetre . In the CGSbase units , it is equal to onegram centimetre-squared persecond -squared (g⋅cm2 /s2 ). It is thus equal to 10−7 joules or 100 nanojoules (nJ ) inSI units.
1 erg =−7 J nJ 1 erg =−10 sn⋅msthène -metres 1 erg =× 1011 eV 1 erg =dyn ⋅cm2 /s2 1 erg = 2.77778× 10−11 W⋅h In 1864,Rudolf Clausius proposed the Greek wordἐργον ergon [ 2] [ 3] British Association for the Advancement of Science , including British physicistsJames Clerk Maxwell andWilliam 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 worderg orergon be strictly limited to refer to theC.G.S. unit of energy .[ 4]
In 1922, chemistWilliam Draper Harkins proposed the namemicri-erg as a convenient unit to measure thesurface energy ofmolecules [ 5] surface chemistry .[ 6] [ 7] −14 erg,[ 5] [ 8] [ 9] [ 10] [ 11] −21 joule.
The erg is not a part of theInternational System of Units (SI), which has been recommended since 1 January 1978[ 12] European Economic Community ratified a directive of 1971 that implemented SI as agreed by theGeneral Conference of Weights and Measures .[ 13] Gaussian units , which are widely used inastrophysics [ 14] [better source needed , applications involving microscopic problems and relativistic electrodynamics,[ 15] mechanics [citation needed .
^ Goodell, Thomas Dwight (1889).The Greek in English Henry Holt and Company . p. 40. ^ Clausius, Rudolf (1867). "Appendices to Sixth Memoir [1864]. Appendix A. On Terminology.". InHirst, T. Archer (ed.).The Mechanical Theory of Heat, With Its Applications to the Steam-engine and to the Physical Properties of Bodies 253 . Retrieved2014-03-17 .editions:PwR_Sbkwa8IC. ^ Howard, Irmgard K. (2001)."S is for Entropy. U is for Energy. What Was Clausius Thinking?" (PDF) .Journal of Chemical Education .78 (4): 505.Bibcode :2001JChEd..78..505H .doi :10.1021/ed078p505 . Retrieved2014-03-17 . ^ Thomson, Sir W ;Foster, Professor GC ;Maxwell, Professor JC ;Stoney, Mr GJ ;Jenkin, Professor Fleeming ;Siemens, Dr ;Bramwell, Mr FJ (September 1873).Everett, Professor (ed.).First Report of the Committee for the Selection and Nomenclature of Dynamical and Electrical Units . Retrieved2014-03-17 .^a b Jerrard, H. G.;McNeill, D. B. (1993) [1963].A Dictionary of Scientific Units - Including dimensionless numbers and scales (6 ed.). London: Chapman and Hall. p. 100.ISBN 0412467208 OCLC 803100353 .OL 1351307M . ^ Cardarelli, François (1999) [1966].Scientific unit conversion: A practical guide to metrication Springer-Verlag London Limited .doi :10.1007/978-1-4471-0805-4 .ISBN 978-1-85233-043-9 . Retrieved2015-08-25 . ^ Cardarelli, François (2003).Encyclopaedia of Scientific Units, Weights and Measures Springer-Verlag London Ltd. ISBN 978-1-4471-1122-1 ^ Roberts, Lathrop Emerson;Harkins, William Draper ; Clark, George Lindenberg (2013-07-01) [1922].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 . Retrieved2015-08-25 . ^ Holmes, Harry N. (1925).Colloid Symposium Monograph - Papers Presented at the Second National Symposium on Colloid Chemistry, Northwestern University, June, 1924 . Retrieved2015-02-15 . ^ "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" .Journal of the American Chemical Society .44 .American Chemical Society : 665. 1922.ISSN 0002-7863 . Retrieved2015-02-15 .^ Partington, James Riddick (2010-02-17) [1949].An Advanced Treatise on Physical Chemistry: Fundamental principles. The properties of gases . Retrieved2015-08-25 .^ Neufert, Ernst; Neufert, Peter; Kister, Johannes (2012-03-26).Architects' Data ISBN 9781405192538 ^ Jennings, W. A. (October 1972)."SI units in radiation measurement" .The British Journal of Radiology .45 (538):784– 785.doi :10.1259/0007-1285-45-538-784 .ISSN 0007-1285 .PMID 5078949 . ^ "Are ergs commonly used in astrophysics? If so, is there a specific reason for it?" .Physics Stack Exchange . 2016-02-12. Retrieved2018-09-15 .^ Jackson, John David (2009).Classical electrodynamics (3 ed.). Hoboken, NY: Wiley. p. 784.ISBN 978-0-471-30932-1
Base units Derived non EM units Derived EMU units Derived ESU units
