A wheel is rotating at 900rpm about its axis . When the power is cut off ,it comes to rest In 1 min. The angular retardation in red `s^(-2)`

Options

A. `pi/2`
B. `pi/4`
C. `pi/6`
D. `pi/8`

Answer

A

Explanation

Use `omega=omega_"o"+alphat" "(i)`
Given ,n `=900"rpm"=(900)/(60)"rpm",omega=oand t=1min=60s`
`therefore " "omega_o =2pin_(1)=(2pixx900)/(60),alpha=(omega-omega_o)/(t) "" (ii)`
`=(0-2pixx900)/(60)^(2)="-"pi/2rads^(-2)`