Wikipedia

Erg

For other uses, seeErg (disambiguation)."Ergs" redirects here. For other uses, seeErgs (disambiguation)."Micro-erg" redirects here. Not to be confused withMicro ERG.

Theergis a unit of energy equal to 10−7joules(100nJ). It originated in theCentimetre–gram–second system of units(CGS). It has the symbolerg.The erg is not anSI unit.Its name is derived fromergon(ἔργον), aGreekword meaning 'work' or 'task'.[1]

erg
Unit systemCGS units
Unit ofenergy
Symbolerg
Derivation1 erg = 1 dyn⋅cm
Conversions
1 ergin...... is equal to...
CGS base units1 cm2⋅g⋅s−2
SI units10−7J
British Gravitational System7.375621×10−8ft⋅lbf

An erg is the amount of work done by a force of onedyneexerted for a distance of onecentimetre.In the CGSbase units,it is equal to onegramcentimetre-squared persecond-squared (g⋅cm2/s2). It is thus equal to 10−7joulesor 100 nanojoules (nJ) inSIunits.

  • 1 erg =10−7J=100nJ
  • 1 erg =10−10sn⋅m=100 psn⋅m=100 picosthène-metres
  • 1 erg =624.15 GeV=6.2415×1011eV
  • 1 erg =1dyn⋅cm=1 g⋅cm2/s2
  • 1 erg = 2.77778×10−11W⋅h

History

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In 1864,Rudolf Clausiusproposed the Greek wordἐργον(ergon) for the unit of energy, work and heat.[2][3]In 1873, a committee of theBritish Association for the Advancement of Science,including British physicistsJames Clerk MaxwellandWilliam Thomsonrecommended 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 wordergorergonbe strictly limited to refer to theC.G.S. unit of energy.[4]

In 1922, chemistWilliam Draper Harkinsproposed the namemicri-ergas a convenient unit to measure thesurface energyofmolecules[5]insurface chemistry.[6][7]It would equate to 10−14erg,[5][8][9][10][11]the equivalent to 10−21joule.

The erg is not a part of theInternational System of Units(SI), which has been recommended since 1 January 1978[12]when theEuropean Economic Communityratified a directive of 1971 that implemented SI as agreed by theGeneral Conference of Weights and Measures.[13]It is the unit of energy inGaussian units,which are widely used inastrophysics[14][better source needed],applications involving microscopic problems and relativistic electrodynamics,[15]and sometimes inmechanics[citation needed].

See also

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References

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  1. ^Goodell, Thomas Dwight (1889).The Greek in English(2nd ed.).Henry Holt and Company.p. 40.
  2. ^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.London: J. Van Voorst. p.253.Retrieved2014-03-17.editions:PwR_Sbkwa8IC.
  3. ^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.
  4. ^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.Forty-third Meeting of the British Association for the Advancement of Science. Bradford: John Murray. p. 224.Retrieved2014-03-17.
  5. ^abJerrard, 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.ISBN0412467208.OCLC803100353.OL1351307M.
  6. ^Cardarelli, François (1999) [1966].Scientific unit conversion: A practical guide to metrication(2 ed.).Springer-Verlag London Limited.doi:10.1007/978-1-4471-0805-4.ISBN978-1-85233-043-9.1447108051, 9781447108054.Retrieved2015-08-25.
  7. ^Cardarelli, François (2003).Encyclopaedia of Scientific Units, Weights and Measures.Springer-Verlag London Ltd.ISBN978-1-4471-1122-1.
  8. ^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.University of Chicago.Retrieved2015-08-25.{{cite book}}:|work=ignored (help)
  9. ^Holmes, Harry N. (1925).Colloid Symposium Monograph - Papers Presented at the Second National Symposium on Colloid Chemistry, Northwestern University, June, 1924.Vol. 2. The Chemical Catalog Company, Inc.Retrieved2015-02-15.
  10. ^"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.ISSN0002-7863.Retrieved2015-02-15.
  11. ^Partington, James Riddick(2010-02-17) [1949].An Advanced Treatise on Physical Chemistry: Fundamental principles. The properties of gases.Vol. 1. Longmans, Green.Retrieved2015-08-25.
  12. ^Neufert, Ernst; Neufert, Peter; Kister, Johannes (2012-03-26).Architects' Data.John Wiley & Sons.ISBN9781405192538.
  13. ^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.ISSN0007-1285.PMID5078949.
  14. ^"Are ergs commonly used in astrophysics? If so, is there a specific reason for it?".Physics Stack Exchange.2016-02-12.Retrieved2018-09-15.
  15. ^Jackson, John David (2009).Classical electrodynamics(3 ed.). Hoboken, NY: Wiley. p. 784.ISBN978-0-471-30932-1.
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