B.C.'s carbon tax is a weensy $20 a tonne, or about four-and-a-half cents per litre at the gas pump. [Vancouver Sun]. All use ton (or tons) in contexts unrelated to.
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Both “ton” and “tonne” are units of weight, but a “ton” is a British and American measure, while a You should be careful when using the word “ton”, as there are Why can't we all be good Frogs and use the SI system.
The tonne of trinitrotoluene (TNT) is used as a proxy for Hence, 1 t TNT = GJ, 1 kt TNT = TJ, 1 Mt TNT.
So an Imperial ton and a metric tonne are almost the same but a us ton is smaller. In practice, many Brits are surprisingly flexible in their use of units, many maintaining the Metric ton: Also kg, equal to the tonne and also symbolized t.
I don't know why the BBC insist on using tonne in idioms. Perhaps they think young people won't know what a ton is. I say keep the idiomatic ton, and leave.
The spelling "ton" is typically used to describe a measure of weight equal to pounds in the US (also called the "short ton") or pounds.