n.
Common unit of power , the rate at which work is done.
In the English system, one horsepower equals 33,000 foot-pounds of work per minute
that is, the power necessary to lift a total of 33,000 lbs a distance of one foot in one minute. This value was adopted by James Watt in the late 18th century after experiments with strong dray horses and is actually about 50% more than the rate an average horse can sustain for a working day. The electrical equivalent of one horsepower is 746 watts in the International System of Units ; the heat equivalent is 2,545 BTU per hour. The metric horsepower (see metric system ) equals 4,500 kg-m per minute (32,549 foot-pounds per minute), or 0.9863 horsepower.