Horsepower is the imperial (British) unit of power, now replaced by the watt - the new SI unit.
One horsepower is the work done at the rate of 550 foot-pounds per second and it is equivalent to 745.7 watts. Horsepower was first used by James Watt, who employed it to compare the power of steam engines with that of horses.
Answered by: Anton Skorucak, M.S. Physics, PhysLink.com Creator

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