Transportation Science

Where did the term "horsepower" come from?
• ### Discovery Channel

1. The term "horsepower" was coined by James Watt, a Scottish inventor and engineer who lived from 1736 to 1819 and greatly improved steam engine performance. At some point, Watt was using ponies to raise coal out of a mine and needed a way to describe the animals' output. Watt calculated that a pony was able to complete 22,000 foot-pounds of work per minute, and then he upped the number by about 50 percent, setting the capability of horse at 33,000 foot-pounds of work per minute. A dynamometer measures how much horsepower an engine produces. It puts a load on the engine and tests the power the engine can produce against that load. Different loads help measure horsepower at different rpms. In order to produce a horsepower rating, the dynamometer measures torque in pound-feet. The torque is then converted to horsepower by multiplying it by the rpm and dividing that number by 5,252.

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