出典:Wikipedia
出典:『Wikipedia』 (2011/06/06 16:01 UTC 版)
Rotational speed (sometimes called speed of revolution) tells how many complete rotations (i.e. revolutions or cycles) there are per time unit. It is therefore a cyclic frequency, measured in hertz (revolutions per second) in the SI System. The units revolutions per minute (rpm or 1/min) are more common in everyday life.