VIDEO TRANSCRIPT

This is Giancoli Answers with Mr. Dychko. A watch has base units of, well almost base units anyway, you can reduce it to this far anyhow, newton meters per second. I mean I suppose you could express the newtons as, you know, mass times acceleration, if you like. But anyways, that's good enough. So we wanna take this 550 feet pounds per second and turn it into newton meters per second. So let's introduce one conversion that will introduce a unit that we want, which is newtons, and get rid of the unit that we don't want, like pounds. So we have 4.45 newtons per pound so the pounds cancel and you are left with newtons, so that's good. And then we'll, at this next conversion factor which introduces meters on top and gets rid of feet in the process; so there's 1 meter for every 3.28 feet. So we have 550 times 4.45 divided by 3.28, which is 746 newton meters per second, which is watts. So we have shown that 1 horsepower, British horsepower, is 746 watts. So if you have a 75 watt light bulb, and multiply it by 1 horsepower for every 746 watts, then your light bulb has 0.10 horsepower.