| 词源 |
horsepower. A car’s horsepower is actually about one and a half times the power of a horse. Seeking a way to indicate the power exerted by his steam engine, inventor James Watt calcu- lated that a strong dray horse averaged 22,000 foot-pounds per minute working at a gin on an eight-hour-a-day basis. Increas- ing this by 50 percent, Watt got 33,000 foot-pounds, which has ever since been one horse-power: “The standard theoretical unit of rate of work, equal to the raising of 33,000 pounds one foot high in one minute.” |