<Dl> <Dd> f = 1 T . (\ displaystyle f = (\ frac (1) (T)).) </Dd> </Dl> <Dd> f = 1 T . (\ displaystyle f = (\ frac (1) (T)).) </Dd> <P> The SI derived unit of frequency is the hertz (Hz), named after the German physicist Heinrich Hertz . One hertz means that an event repeats once per second . A previous name for this unit was cycles per second (cps). The SI unit for period is the second . </P> <P> A traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r / min or rpm . 60 rpm equals one hertz . </P>

What is the si unit of time period