Question

A wheel is rotating at 900 rpm about its axis. When the power is cut off, it comes to rest in 1 min. The angular retardation (in rad `s^(-2)`) is
A. `(pi)/(2)`
B. `(pi)/(4)`
C. `(pi)/(6)`
D. `(pi)/(8)`

Answer 1

Correct Answer - A
As, `omega=omega_(0)+alphat`
Here, `omega_(0)=900"rpm"=((2pixx900))/(60)"rad s"^(-1),omega=0`
and `t=60s, 0=(2pixx900)/(60)+alphaxx60`
`alpha=(2pixx900)/(60xx60)=(pi)/(2)`