Power.—The term power means the rate at which work is done; it is usually expressed as the number of foot pounds done in one minute, that is
power = (foot pounds) / minutes
Power exerted for a certain time produces work.
Ques. What is the mechanical unit of power?
Ans. The horse power.
Ques. What is one horse power?
Ans. 33,000 foot pounds per minute.
The unit is due to James Watt as being the power of a strong London draught horse to do work during a short interval and used by him to measure the power of his steam engines. One horse power = 33,000 ft. lbs. per minute = 550 ft. lbs. per sec. = 1,980,000 ft. lbs. per hour.
Ques. What is one horse power hour?
Ans. Work done at the rate of one horse power for one hour.