Tonne

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Tonne
Megagram
SI units
:
1000 kg

The tonne (

pounds
, 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram (Mg), a less common way to express the same amount.

Symbol and abbreviations

The

petajoules
.

Origin and spelling

In English, tonne is an established spelling alternative to metric ton.[4] In the United States and United Kingdom, tonne is usually pronounced the same as ton (/tʌn/), but the final "e" can also be pronounced, i.e. "tunnie" (/ˈtʌni/).[5] In Australia, the common and recommended pronunciation is /tɒn/.[6][7] In the United States, metric ton is the name for this unit used and recommended by NIST;[2] an unqualified mention of a ton almost invariably refers to a short ton of 2,000 lb (907.2 kg) and to a lesser extent to a long ton of 2,240 lb (1,016 kg), with the term tonne rarely used in speech or writing. Both terms are acceptable in Canadian English.

Ton and tonne are both derived from a Germanic word in general use in the North Sea area since the Middle Ages (cf. Old English and Old Frisian tunne, Old High German and Medieval Latin tunna, German and French tonne) to designate a large cask, or tun.[8] A full tun, standing about a metre high, could easily weigh a tonne.

The spelling tonne pre-dates the introduction of the SI in 1960; it has been used with this meaning in France since 1842,[9] when there were no metric prefixes for multiples of 106 and above, and is now used as the standard spelling for the metric mass measurement in most English-speaking countries.[10][11][12][13] In the United States, the unit was originally referred to using the French words millier or tonneau,[14] but these terms are now obsolete.[15]The British imperial and United States customary units are comparable to the tonne and the spelling of ton in English is the same, though they differ in mass.

Conversions

One tonne is equivalent to:

  • In kilograms: 1000 kilograms (kg) by definition.[16]
  • In grams: 1000000 grams (g) or 1 megagram (Mg). Megagram is the corresponding official SI unit with the same mass. Mg is distinct from mg, milligram.
  • In pounds: Exactly 1000/0.45359237 pounds (lb) by definition of the pound,[17] or approximately 2204.622622 lb.[18]
  • In short tons: Exactly 1/0.90718474 short tons (tn), or approximately 1.102311311 tn.
    • One short ton is exactly 0.90718474 t.[19]
  • In long tons: Exactly 1/1.0160469088 long tons (LT), or approximately 0.9842065276 LT.
    • One long ton is exactly 1.0160469088 t.[19]

A tonne is the mass of one cubic metre of pure water at 4 °C (39 °F).[a]

Derived units

As a non-SI unit, the use of SI metric prefixes with the tonne does not fall within the SI standard. For multiples of the tonne, it is more usual to speak of thousands or millions of tonnes. Kilotonne, megatonne, and gigatonne are more usually used for the energy of nuclear explosions and other events in equivalent mass of TNT, often loosely as approximate figures. When used in this context, there is little need to distinguish between metric and other tons, and the unit is spelled either as ton or tonne with the relevant prefix attached.[b]

Tonnes Grams Equivalents*
Name Symbol Name Symbol Tonnes (t) Short Tons (tn) Long Tons (LT)
tonne t megagram Mg 1 t 1.1023 tn 0.98421 LT
kilotonne ktǂ gigagram Gg 1,000 t 1102.3 tn 984.21 LT
megatonne Mt teragram Tg 1,000,000 t 1.1023 million tn 984210 LT
gigatonne Gt petagram Pg 1,000,000,000 t 1.1023 billion tn 984.21 million LT

*The equivalent units columns use the

short scale
large-number naming system currently used in most English-language countries, e.g. 1 billion = 1000 million = 1000000000.
Values in the equivalent short and long tons columns are rounded to five significant figures. See Conversions for exact values.
ǂThough non-standard, the symbol "kt" is also used (instead of the standard symbol "kn") for knot, a unit of speed for aircraft and watercraft. The standard meaning of the symbol kt is for kilotonne.

Alternative usages

Metric ton units

A metric ton unit (mtu) can mean 10 kg (22 lb) within metal trading, particularly within the United States. It traditionally referred to a metric ton of ore containing 1% (i.e. 10 kg) of metal.[20][21] The following excerpt from a mining geology textbook describes its usage in the particular case of tungsten:

Tungsten concentrates are usually traded in metric tonne units (originally designating one tonne of ore containing 1% of WO3, today used to measure WO3 quantities in 10 kg units. One metric tonne unit (mtu) of tungsten (VI) contains 7.93 kilograms of tungsten.

— Walter L Pohl, Economic Geology: Principles and Practices, English edition, 2011, p 183.

In the case of uranium, MTU is sometimes used in the sense of metric ton of uranium (1,000 kg (2,200 lb)).[22][23][24][25]

Use of mass as proxy for energy

The tonne of

PJ
.

The SI unit of energy is the joule. One tonne of TNT is approximately equivalent to 4.2 gigajoules.

In the

crude oil
, approximately 42 GJ. There are several slightly different definitions. This is ten times as much as a tonne of TNT because atmospheric oxygen is used.

Unit of force

Like the gram and the kilogram, the tonne gave rise to a (now obsolete) force unit of the same name, the tonne-force, equivalent to about 9.8 kilonewtons. The unit is also often called simply "tonne" or "metric ton" without identifying it as a unit of force. In contrast to the tonne as a mass unit, the tonne-force is not accepted for use with SI.

See also

Notes and references

Notes
  1. ^ To within 0.003%.
  2. ^ The Oxford English Dictionary 2nd ed. gives both megaton and megatonne and adds "The unit may be calculated in either imperial or metric tons; the form megatonne generally implies the metric unit". The use for energy is the first definition; use for mass or weight is the third definition.
Citations
  1. ^ Table 6 Archived 2009-10-01 at the Wayback Machine. BIPM. Retrieved on 2011-07-10.
  2. ^ a b Metric System of Measurement: Interpretation of the International System of Units for the United States Archived 2008-04-09 at the Wayback Machine (PDF). See corrections in the Errata section of [1] Archived 2008-04-18 at the Wayback Machine.
  3. ^ NIST Special Publication 330, 2019 edition states "The name of the unit with symbol t and defined according to 1 t = 103 kg is called 'metric ton' rather than 'tonne.'".
  4. OED
    . Retrieved 6 August 2021.
  5. ^ The Oxford English dictionary 2nd ed. lists both /tʌn/ and /ˈtʌni/
  6. ^ Macquarie Dictionary (fifth ed.). Sydney: Macquarie Dictionary Publishers Pty Ltd. 2009.
  7. ^ "How To Pronounce Metrics Units (advertisement by Australian Metric Conversion Board)". The Age. 1972-11-21. p. 14. Retrieved 2021-11-01.
  8. ^ Harper, Douglas. "tonne". Online Etymology Dictionary.
  9. ^ "Recherche d'un mot". atilf.atilf.fr.
  10. ^ "Guidance Note on the use of Metric Units of Measurement by the Public Sector" (PDF). National Measurement Office. 2007. Archived from the original (PDF) on 2011-02-07. Retrieved 2010-02-13. "Tonne" is listed under "The Principal Metric Units of Measurement" on p. 7.
  11. ^ "National Measurement Regulations 1999 |". Australian Government. 1999. Retrieved 2010-02-13. "Tonne" is listed under Schedule 1, Part 3 as a non-SI unit of measurement used with SI units of measurement.
  12. ^ "Appendix 4: Units of Measurement and Conversion Factors". MAF (Ministry of Agriculture and Forestry (New Zealand)). Retrieved 2010-02-13.
  13. ^ "Canada Gazette". Government of Canada. 1998–2007. Archived from the original on 2011-07-06. Retrieved 2010-02-13. The Corporation shall pay to producers selling and delivering wheat produced in the designated area to the Corporation the following sums certain per tonne basis...
  14. ^ Act of July 28, 1866, codified in 15 U.S.C. § 205
  15. ^ "Metric System of Measurement: Interpretation of the International System of Units for the United States" (PDF). Federal Register. 63 (144): 40338. July 28, 1998. 63 FR 40333. Archived from the original (PDF) on October 15, 2011.
  16. ^ Barbrow, L.E.; Judson, L.V. (1976). Weights and measures standards of the United States – A brief history. Archived from the original on 2008-05-11.
  17. ^ United States National Bureau of Standards (1959-06-25). "Notices "Refinement of values for the yard and the pound"" (PDF). Retrieved 2006-08-12.
  18. ^
    OCLC 58927093
    . Retrieved 10 December 2013.
  19. ^ "Platt's Metals Guide to Specifications – Conversion Tables". 8 September 2008. Archived from the original on 8 September 2008.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
  20. ^ How Many? A Dictionary of Units of Measurement Archived 2011-09-04 at the Wayback Machine. Unc.edu. Retrieved on 2011-07-10.
  21. ^ Reference.Pdf. (PDF) . Retrieved on 2011-07-10.
  22. ^ "Glossary Archived 2010-03-14 at the Wayback Machine". (June 2000). Disposition of Surplus Hanford Site Uranium, Hanford Site, Richland, Washington. US Department of Energy.
  23. ^ "Acronyms Archived 2013-03-12 at the Wayback Machine". Y-12 National Security Complex.
  24. ^ NRC Collection of Abbreviations (NUREG-0544, Rev. 4), United States Nuclear Regulatory Commission. Nrc.gov (2011-03-13). Retrieved on 2011-07-10.

External links

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