American Customary Measurements: Difference between revisions

'''Power:''' The common unit of power in the United States is the horsepower. There are five different types of horsepower, just to be even more confusing. The most common is Mechanical horsepower (more often called brake horsepower, from the method used to derive it) which is used by auto manufacturers to tell [[Viewers Areare Morons|the public]] that their car is more powerful and therefore makes you more of a man if you own it. 1 unit of mechanical horsepower is 550 foot-pounds per second (~745.7 W). There is also metric horsepower, electrical horsepower, boiler horsepower, and hydraulic horsepower, all of which can be safely ignored, with the sole exception of metric horsepower, which is sometimes used to rate power outputs of automobiles and other engines in Europe and always used for cars in Japan. The metric horsepower is sometimes called the Pferdestaerke (German for "horse strength") and abbreviated "PS" or (rarely) "cv". The metric horsepower is slightly smaller than its American equivalent, at 735.49875 W --for instance, the old Japanese output limit of 280 PS for sports cars is around 276 bhp. You'll also hear references to "SAE net" or "gross" horsepower; specific to car engines, these terms have to do with the testing standard, not the units themselves. SAE gross horsepower, the standard for the auto industry until 1972 and still used in the trucking industry, is measured on a test stand in a pressurized room, with coolant and oil pumped through from outside sources so the engine doesn't have to spin its own pumps. In other words, rigged to give the highest number possible.