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)-2a theta`
`=-4pi^(2)n^(2)-2a theta`
`theta(4pi^(2)((1200)/(60))^(2))/(2xx4)`
`=200 pi^(2) rad`
`therefore 2pin=200 pi^(2)`
`n=100pi=100xx3.14=314` revoluation