Horsepower

Horsepower, unit of power used to indicate the rate at which work is done. In the 18th century inventor James Watt experimentally determined that a strong horse can lift up to 33,000 foot-pounds 1 foot per minute. This has become the definition of 1 horsepower. In electrical units 1 horsepower is equivalent to 746 watts; the heat equivalent is 2, 545 BTU (British thermal units) per hour.