Question

A fan is rotating with angular velocity `100 rev s^-1`. Then is switched off. It takes `5 min`to stop.
(a) Find the total number of revolution made before the fan stops. (assume uniform angular retardation).
(b) Find the value of angular retardation.
( c) Find the average angular velocity during this interval.

Answer 1

(a) `theta = ((omega + omega_0)/(2)) t = ((100 + 0)/(2)) xx 5 xx 60 = 15000 rev`.
(b) `omega = omega_0 + prop t`
`rArr 0 = 100 - prop (5 xx 60) rArr prop = (1)/(3) rev s^-2`
( c) `omega_(a v) = ("Total angle of rotation")/("Total time taken")`
=`(15000)/(50 xx 60) = 50 rev s^-1`.