User:Milton Beychok/Sandbox: Difference between revisions

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A '''tonne''' (t) or '''metric tonne''' (also referred to as a '''metric ton'''), is a measurement of [[mass]] equal to 1000 [[kg]], or almost exactly the mass of one cubic [[metre]] of pure [[water]] at 3.98 °[[Celsius|C]].<ref>The [[density]] of air-free water at a [[pressure]] of 1 [[Pressure|atmosphere]] and 3.98 °C is 999.974 kg per cubic metre. &nbsp; September 2001, The [[International Association for the Properties of Water and Steam]] [http://www.iapws.org/relguide/fundam.pdf Guideline on the Use of Fundamental Physical Constants and Basic Constants of Water]</ref> It is not an [[SI]] unit but is accepted for use with the SI.<ref>Section 4.1 of [http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf The [[International System of Units]] (SI)] (PDF), 8th Edition, 2006</ref>


Using the SI prefixes, the correct SI terminology for a tonne would be a ''megagram'' (Mg) but this term is not often used. In most countries, ''tonne'' is used as the standard terminology for the metric mass measurement.
== Origin ==
There does not appear to be a definitive concensus as to the origin or [[etymology]] of the word ''tonne''.<ref>[http://www.bartelby.net/61/41/T0264100.html tonne] The [[American Heritage Dictionary]] of the English Language, Fourth Edition, 2000</ref><ref>{{cite book|author=Eric Partridge|title=Origins: an etymological dictionary of modern English|edition=4th Edition|publisher=Routledge|year=1966|id=ISBN 0-415-050-744}}</ref><ref>[http://www.etymonline.com/index.php?term=ton ton] Online Etymology Dictionary</ref><ref>[http://www.thefreedictionary.com/tonne tonne] The Free Dictionary</ref> Most sources indicate that it has a [[Celtic language|Celtic]] or [[Gaelic language|Gaelic]] origin that led to the [[Latin language|Latin]] word ''tunna'' and to the words ''tun'' and ''tonne'' in [[French language|French]] and [[English language|English]]. In the evolution of both of those languages, ''tun'' and ''tonne'' originally referred to a a barrel or cask with a volume of about 954 [[litre]]s (almost a cubic metre), which for wine, beer  and many commonly used [[aqueous]] [[solution]]s would weigh about a tonne.
== Conversions ==
One tonne equals:
* Exactly 1 megagram (1 Mg)
* Exactly 1000 kilograms
* Exactly 1 metric tonne (or 1 metric ton)
* 2204.62 [[U.S. customary units|pounds]] (to 6 [[signicant digits]])
* 0.98421 [[U.S. customary units|long ton]] (to 5 significant digits)
* 1.1023 [[U.S. customary units|short ton]] (to 5 significant digits)
== Other usage of the word tonne ==
The word tonne is also used to express quantities other than mass, such as:
* A tonne of [[coal]] equivalent (TCE) ≈ 29.31 G[[Joule|J]] (varies from one coal to another)
* A tonne of oil equivalent (TOE) ≈ 41.87 GJ (varies from one [[petroleum crude oil]] to another)
* A tonne of TNT ([[trinitrotoluene]]) [[explosive]] = 4.18 GJ
* A tonne of [[refrigeration]] = 13,898 kJ/h = 3.861 k[[Watt|W]]
** A ton of refrigeration = 12,000 Btu/h = 3.517 kW (A ton of refrigeration is defined slightly differently than a tonne of refrigeration)
== References ==
{{reflist}}

Revision as of 11:10, 8 May 2009

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