A wheel has a speed of `1200` revolution per minute and is made to slow down at a rate of `4 rad//s^(2)`. The number of revolutions it makes before coming to rest is

Options

A. 143
B. 272
C. 314
D. 722

Answer

C

Explanation

`omega^2=omega_0^2-2athetaor0=4pi^2n^2-2atheta`
`theta=(4pi^2(1200)/(60))^2/(2xx4)=200pi^2rad``omega^2=omega_0^2-2athetaor0=4pi^2n^2-2atheta`
`theta=(4pi^2(1200)/(60))^2/(2xx4)=200pi^2rad`
`therefore" "2pin=200pi^2`
`rArr" "n=100pi=314revolution`