The short ton sometimes describes force. One short-ton contains 2,000 pounds-mass, which converted into slugs and multiplied by one standard gravity applies a weight of 2,000 pounds-force as per Newton's second law of motion.
In the United States, a short ton is usually known simply as a "ton",  without distinguishing it from the tonne (1,000 kilograms or 2,204.62262 pounds), known there as the "metric ton", or the long ton also known as the "Imperial ton" (2,240 pounds or 1,016.0469088 kilograms). There are, however, some U.S. applications where unspecified tons normally means long tons (for example, naval ships)  or metric tons (world grain production figures).
Both the long and short ton are defined as 20 hundredweights, but a hundredweight is 100 pounds (45.359237 kg) in the U.S. system (short or net hundredweight) and 112 pounds (50.802345 kg) in the imperial system (long or gross hundredweight). 
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In the United Kingdom, short tons are rarely used. The word "ton" is taken to refer to a long ton, and metric tons are distinguished by the "tonne" spelling. Most Commonwealth countries followed British practice with the exception of Canada, which used short tons as well as long tons. Canada now predominantly uses metric tons (tonnes).
- Long ton, 2,240 lb (1,016.0469088 kg)
- Tonne, also known as a metric ton (t), equal to 1,000 kg (2,204.6226218 lb) or 1 megagram.
- Tonnage, volume measurement used in maritime shipping, originally based on 100 cubic feet (2.83168 m3).
"NIST Handbook 44 Specifications: Handbook 44 – 2013 Appendix C – General Tables of Units of Measurement" (PDF). April 26, 2006. p. C-6. Retrieved October 13, 2008.
20 hundredweights = 1 ton
- "Naval Architecture for All". United States Bureau of Transportation Statistics. Retrieved October 13, 2008.