Information AboutTonne |
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| units of mass | |
| non-si metric units | |
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A tonne (symbol t), sometimes referred to as a ''metric tonne'', is a measurement of weight. It is not an SI unit but is accepted for use with the SI. Though the spelling ''tonne'' predates the introduction of the SI system in 1960 it is now used as the standard spelling for the metric weight measurement in English. The similar English Unit s are spelled '''ton''' in English. DEFINITION 1 tonne = 1000 kilograms. MULTIPLES ORIGIN The spelling ''tonne'' is from French. In old English the spelling was tunne. The various spellings and meanings (tonne, ton, tun) derive from the late Latin ''tunna'', "cask" - a full cask about a metre high could easily weigh a tonne. It may also be of Celtic origin. CONVERSIONS One tonne is equivalent to:
EXPLANATION The official symbol is t. '''T''' and '''mT''' and '''mt''' (especially in the combination '''mmt''' for "million metric tons") are also sometimes used, but all of these are deprecated since they conflict with internationally agreed SI symbols. (T is the SI symbol for the Tesla and m is SI prefix 'milli', meaning 1000th.) In France and the English-speaking countries that are predominantly metric, the spelling tonne is widespread. However, in Britain, the ton used prior to metrication was the . Like grams and kilograms, tonnes gave rise to a (now obsolete) force unit of the same name: 1 tonne-force = 9.80665 Kilonewtons (kN), a unit also often called simply "tonne" or "metric ton" without identifying it as a unit of force. Note that it is only the tonne as a unit of mass which is accepted for use with SI; the tonne-force or metric ton-force is not acceptable for use with SI. USE OF MASS AS PROXY FOR ENERGY However, the tonne of Trinitrotoluene (TNT) is used as a proxy for energy. Prefixes are also used e.g. kilotonne, megatonne, gigatonne; especially for expressing Nuclear Weapon Yield , based on a Specific Combustion Energy of TNT of 4.184 MJ / Kg (or one Calorie —specifically a ''thermochemical'' calorie—per Milligram ). Hence, 1 Kt TNT = 4.184 TJ , 1 Mt TNT = 4.184 PJ . The SI unit of energy is the Joule . Assuming that TNT contains 1000 small (thermochemical) Calorie s per gram (4.184 KJ /g), one tonne TNT is more correctly referred to as 4.184 Gigajoules . It is usually used to describe the energy of explosions. SEE ALSO
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