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CGS unit of energy and mechanical work
The erg is a unit of energy equal to 10−7
joules (100
n J). It originated in the
Centimetre–gram–second system of units (CGS). It has the symbol erg . The erg is not an
SI unit . Its name is derived from ergon (ἔργον ), a
Greek word meaning 'work' or 'task'.
[1]
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 = 10−7
J = 100
nJ
1 erg = 10−10 sn⋅m = 100 psn⋅m = 100 pico
sthène -metres
1 erg = 624.15 GeV = 6.2415× 1011
eV
1 erg = 1
dyn ⋅cm = 1 g⋅cm2 /s2
1 erg = 2.77778× 10−11 W⋅h
History
In 1864,
Rudolf Clausius proposed the Greek word ἐργον (ergon ) for the unit of energy, work and heat.
[2]
[3] 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 .
[4]
In 1922, chemist
William Draper Harkins proposed the name
micri-erg as a convenient unit to measure the
surface energy of
molecules
[5] in
surface chemistry .
[6]
[7] It would equate to 10−14 erg,
[5]
[8]
[9]
[10]
[11] 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
[12] when the
European Economic Community ratified a directive of 1971 that implemented SI as agreed by the
General Conference of Weights and Measures .
[13] It is the unit of energy in
Gaussian units , which are widely used in
astrophysics
[14] [
better source needed ] , applications involving microscopic problems and relativistic electrodynamics,
[15] and sometimes in
mechanics [
citation needed ] .
See also
References
^ Goodell, Thomas Dwight (1889).
The Greek in English (2nd ed.).
Henry Holt and Company . p. 40.
^
Clausius, Rudolf (1867). "Appendices to Sixth Memoir [1864]. Appendix A. On Terminology.". In
Hirst, 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 . Retrieved 2014-03-17 . 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 . Retrieved 2014-03-17 .
^
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 . Forty-third Meeting of the British Association for the Advancement of Science. Bradford: John Murray. p. 224. Retrieved 2014-03-17 .
^
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 (2 ed.).
Springer-Verlag London Limited .
doi :
10.1007/978-1-4471-0805-4 .
ISBN
978-1-85233-043-9 . 1447108051, 9781447108054. Retrieved 2015-08-25 .
^ 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 . University of Chicago. Retrieved 2015-08-25 .
^ 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. Retrieved 2015-02-15 .
^
"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 . Retrieved 2015-02-15 .
^
Partington, James Riddick (2010-02-17) [1949].
An Advanced Treatise on Physical Chemistry: Fundamental principles. The properties of gases . Vol. 1. Longmans, Green. Retrieved 2015-08-25 .
^ Neufert, Ernst; Neufert, Peter; Kister, Johannes (2012-03-26).
Architects' Data . John Wiley & Sons.
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. Retrieved 2018-09-15 .
^ 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