Ton
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2008-07-16T14:20:47Z
199.144.85.197
{{otheruses}}
{{otheruses4|the imperial ton and similar units|the metric tonne|Tonne}}
{{wiktionary|ton}}
==Units of mass==
There are three similar units of [[mass]] called the '''ton''':
# '''[[long ton]]''' (simply '''ton''' in countries such as the [[United Kingdom]] which formerly used the [[Imperial unit|Imperial system]] of weights and measures) is a '''weight ton''' or '''gross ton''', and is 2,240 pounds (exactly [[1 E3 kg|1,016.0469088 kg]]). In the UK and most of the areas which used the Imperial system, the [[metric ton]] (1,000 kg), which it is conveniently very similar to—less than 2% difference—is the only .
#* Increasingly, metric [[tonne]]s are being used rather than long tons in measuring the displacement of ships. ''See'' [[tonnage]].
# '''[[short ton]]''' (usually called simply '''ton''' in North America or sometimes called a ''net ton'') = 2,000 lb (about [[1 E2 kg|907.18474 kg]]).
#*'''Harbour ton''' used in [[South Africa]] in the 20th century, equal to 2000 pounds or one short ton.
#The '''metric ton''', or '''[[tonne]]''', is 1,000 [[kg]] (or [[1 E3|1 Mg]]) or approximately 2,204.6 [[pound]]s.
Both the long ton and the short ton are composed of twenty [[hundredweight]]s, each having different values for the hundredweight (112 and 100 pounds respectively). Prior to the 15th century in [[England]], the ton was composed of 20 hundredweights, each of 108 lb, giving a ton of 2,160 pounds.
'''Assay ton''' (abbreviation 'AT') is not a unit of measurement (nobody ever has ''x'' assay tons of something), but rather a standard quantity used in [[assay]]ing ores of precious metals; it is {{frac|29|1|6}} grams (short assay ton) or {{frac|32|2|3}} grams (long assay ton), the amount which bears the same ratio to a milligram as a short or long ton bears to a [[troy ounce]]. In other words, the number of milligrams of a particular metal found in a sample of this size gives the number of troy ounces contained in a short or long ton of ore.
In documents that predate 1960 the word ''ton'' is sometimes spelled ''tonne''; however, in more recent documents the spelling ''tonne'' refers exclusively to the [[metric ton]].
In the context of [[nuclear power plant]]s, '''tHM''' and '''MTHM''' mean (metric) tonnes of [[heavy metals]], and MTU means metric tonnes of [[uranium]]. In the [[steel]] industry, the acronym '''THM''' has the meaning 'tons/tonnes hot metal', which refers to the amount of liquid iron or steel that is produced (particularly in the context of [[blast furnace]] production or specific consumption).
A '''dry ton''' or '''dry tonne''' has the same mass value, but the material ([[sludge]], slurries, [[compost]], and similar mixtures in which solid material is soaked with or suspended in [[water]]) has been dried to a relatively low, consistent [[moisture]] level ([[dry weight]]). If the material is in its natural, wet state, it is called a '''wet ton''' or '''wet tonne'''.
==Common abbreviations==
In the U.S. mining industry, 'T' is used to distinguish the traditional ton from the metric ton, but 'T' is also the SI symbol for the [[Tesla (unit)|tesla]]. The symbol 't', traditionally used for the long or short ton, is now reserved for the metric ton.
==Units of force==
There are also the units of force based on each of these three mass units, but none are acceptable for use with [[SI]]. The tonne force, like the kilogram force, is no exception. Only the tonne as a unit of mass is acceptable for use with SI.
*1 short ton force = 2000 [[pound-force|pounds-force]] (lbf) = 8.896443230521 [[kilonewton]]s (kN)
*1 long ton force = 2240 lbf = 9.96401641818352 kN
*1 tonne force = 1000 [[kilogram-force|kgf]] = 9.80665 kN
==Units of volume==
Also see [[tonnage]].
The displacement ton is a unit of volume used for describing the displacement of (usually) a warship. It represents the volume of water displaced by the ship. One measurement ton is equal to 35 [[cubic foot|cubic feet]] or 0.99108963072+ [[cubic metre]]s. Coincidentally, 35 cubic feet of water weighs very close to 1 tonne, but the tonne had not been defined when the displacement ton was. Consequently it is less approximately equal to 1 [[long ton]] of water (2240 lbs). It is usually abbreviated as '''DT'''.
The freight ton represents the volume of a truck, train or other freight carrier. In the past it has been used for a cargo ship but the register ton is now prefered. It is today equal to 40 cubic feet of space (1.132 cubic metres), but historically it has had several informal definitions. It is correctly abbreviated as 'FT' but some users are now using freight ton to represent a weight of 1 tonne, thus the more common abbreviations are now '''M/T''', '''MT''', or '''MTON''' (for measurement ton), which still cause it to be confused with the [[tonne|metric ton]] or even the [[megaton]].
The '''register ton''' is also a unit of volume used for the cargo capacity of a ship, defined as 100 cubic feet (roughly 2.83 cubic metres). It is often abbreviated '''RT''' or '''GRT''' for '''gross registered ton''' (The former providing confusion with the refrigeration ton). It is known as a ''tonneau de mer'' in Belgium, but, in France, a ''tonneau de mer'' is 1.44 cubic metres or about 1.88 cubic yards.
The '''Panama Canal net ton''', a unit of volume used for billing for ships going through the [[Panama Canal]], is the same as the register ton. The fee for example in the 1990s was roughly a couple [[USD]] for each unit.
The '''water ton''' was formerly used in Great Britain and equal to 224 [[imperial gallon]]s (the volume occupied by a mass of one long ton under the conditions which define the imperial gallon).
See [[1 E-1 m³]] and [[orders of magnitude (volume)]] for a comparison with other volumes.
(Note that volume tons are units of convenience used in shipping and are not useful in science except that they are exactly defined.)
==Units of energy and power==
===Ton of TNT===
{{mainarticle|TNT equivalent}}
*A '''ton of TNT''' or ''tonne of TNT'' is a unit of energy equal to 10<sup>9</sup> (thermochemical) [[calorie]]s, also known as a gigacalorie (Gcal), equal to 4.184 [[gigajoule]]s (GJ).
*A '''kiloton of TNT''' or ''kilotonne of TNT'' is a unit of energy equal to 10<sup>12</sup> calories, also known as a teracalorie (Tcal), equal to 4.184 terajoules (TJ).
*A '''[[megaton]] of TNT''' (1,000,000 metric tonnes) or ''megatonne of TNT'' is a unit of energy equal to 10<sup>15</sup> calories, also known (infrequently) as a petacalorie (Pcal), equal to 4.184 petajoules (PJ).
Note that these are small calories (cal). The dietary Calorie (Cal) is distinct and equal to one kilocalorie.
Early values for the explosive energy released by [[trinitrotoluene]] (TNT) ranged from 900 to 1100 calories per gram. In order to standardise the use of the term ''TNT'' as a unit of energy, an arbitrary value was assigned based on 1000 calories (1 kcal, 4.184 kilo[[joules]]) per gram. Thus there is no longer a direct connection to the chemical TNT itself. It is now merely a unit of energy that happens to be expressed using words normally associated with mass (e.g. kilogram, tonne, pound).<ref>[http://www.iaea.org/About/Policy/GC/GC42/Documents/gc42inf3.pdf GC(42)/INF/3 - Measures to Strengthen Co-operation in Nuclear, Radiation and Waste Safety<!-- Bot generated title -->]</ref> <ref>http://www.iaea.org/Publications/Magazines/Bulletin/Bull404/article1.pdf</ref> The definition applies for both spellings: ''ton of TNT'' and ''tonne of TNT''.
Measurements in tons of TNT have been used primarily to express [[nuclear weapon yield]]s, though they have also been used since in [[seismology]] as well.
===Ton of coal equivalent===
*A '''ton of coal equivalent''' or ''tonne of coal equivalent'' (TCE), a conventional value of 7 Gcal (IT) = 29.3076 GJ.
===Ton of oil equivalent===
*A '''[[ton of oil equivalent]]''' or ''tonne of oil equivalent'' (TOE), a conventional value of 10 Gcal (IT) = 41.868 GJ ≈ 10.0067 ton of TNT. ''See also'' [[GTOE]].
=== Refrigeration ===
The unit ''ton'' is used in refrigeration and [[air conditioner#Equipment capacity|air conditioning]] to measure heat absorption. Prior to the introduction of mechanical refrigeration, cooling was accomplished by delivering ice. Installing one ton of refrigeration replaced the daily delivery of one ton of ice.
* In North America, from the above a '''standard ton of refrigeration''' is approximately 12,000 [[BTU]]/h = 200 BTU/min ≈ 3.517 [[kilowatt|kW]]. A ton is now taken to be the power required to melt one short ton (2,000 [[pound (mass)|lb]]) of ice at 0 °C in 24 hours (representing the delivery of 1 ton of ice per day).
* A less common usage is the power required to cool 1 long ton of water by 1 °F every 10 minutes = 13,440 BTU/h ≈ 3,939 [[watt|W]].<ref>{{cite web | title =ton (of refrigeration) | url=http://www.sizes.com/units/ton.htm | work = [http://www.sizes.com/ Sizes.com] | accessdate = 2006-09-01}}</ref><ref>{{cite web | title =Measurements and Units| url=http://home.att.net/~numericana/answer/units.htm#othertons | author=Gérard P. Michon | accessdate = 2006-09-01}}</ref><ref>Marks' Standard handbook for Mechanical Engineers, 8th Ed., McGraw Hill, p. 19–3</ref>
The refrigeration ton is abbreviated as '''RT''' providing scope for confusion with the register ton.
==Truck classes==
{{main|Truck classification}}
When light-duty trucks were first produced, they were rated by their payload capacity in tons (e.g., {{frac|1|2}}-, {{frac|3|4}}- and 1-ton). The Ford F-150, Chevy/GMC 1500, and Dodge 1500 are a {{frac|1|2}}-ton. The Ford F-250, Chevy/GMC 2500, and Dodge 2500 are a {{frac|3|4}}-ton. The Ford F-350, Chevy/GMC 3500, and Dodge 3500 are a 1-ton. But throughout the years, the payload capacities have increased while the ton title has stayed the same. The current ton rating scheme is nothing more than just a generic truck name.
==Miscellaneous tons==
* '''Ton''' is also used informally to mean a large amount of something (material or not), for example, "We've been having a ton of good luck recently".
* In Britain, ton is colloquially used to refer to 100 of a given unit. Ton can thus refer to the speed of [[motor vehicles]], namely to the speed of 100 miles per hour e.g. "Lee was doing a ton down the motorway", to money e.g. "How much did you pay for that?" "A ton" (£100), to 100 points in a game e.g. "Eric just threw a ton in our darts game" or to a hundred of pretty much anything else.
A ton is also equivalent to 100 runs in the game of cricket (more commonly known as a century).
==See also==
*[[Conversion of units]]
*[[Medieval weights and measures]]
*[[Ancient weights and measures]]
*[[English unit]]
*[[Imperial unit]]
*[[U.S. customary unit]]
==References==
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[[Category:Units of mass]]
[[Category:Units of volume]]
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