Energy
Popular quickchoices:
kilocalorie (kcal)
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kilojoule (kJ)
kilowatt hour (kW·h)
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kilojoule (kJ)
british thermal unit (Btu)
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kilojoule (kJ)
calorie (cal)
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joule (J)
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*SI (International System of Units):
A modern, coherent system of measurement units, built around seven base units. The SI is officially adopted by almost every country in the world.
*Metric system:
A system of measurement units based on a limited number of fundamental units, introduced by France in 1799. The metric system is the predecessor of the International System of Units (SI).
*Imperial system:
A British measurement system, first standardized in 1824, based on the standard units yard, pound and gallon.