Power from the Stars
1941; Institute of Physics; Volume: 53; Linguagem: Inglês
10.1086/125274
ISSN1538-3873
Autores Resumois defined as the rate of doing work, while work is force times distance. If you push or pull on an object and it moves, you are doing work. If, however, the object is too heavy and does not move, although you may get tired with pushing and pulling, so long as nothing moves no work is done. The unit of power is often taken as the horsepower, defined as 550 foot-pounds per second. If a man weighing 180 pounds runs upstairs at the rate of 3.06 feet per second, he is exerting 180 X 3.06= 550 ftlbs./sec. = 1 horsepower. Electrical power which we get over the wires is usually reckoned in kilowatts ; one kilowatt is equal to 1 . 34 horsepower. Therefore, when you use and pay for one kilowatt-hour you have been given the services of a large-sized horse for one hour.
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