The Probert Encyclopaedia of Science & Technology

HORSEPOWER

Horsepower is an imperial unit of power, now replaced by the watt. It was first used by the engineer James Watt, who employed it to compare the power of steam engines with that of horses. In the UK, one horsepower is equal to 550 foot-pounds per second or 745.7 watts. In the USA this figure has been rounded to 746 watts, and in the metric system it is 735.5 watts.
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