Question

A stationary wheel starts rotating about its own axis at constant angular acceleration. If the wheel completes `50` rotations in first `2` seconds, then the number of rotations mades by it in next two seconds is
A. `75`
B. `100`
C. `125`
D. `150`

Answer 1

Correct Answer - D
`omega=0,t=2s,`
`theta=50(2pi)=100 pi rad`
`:. alpha==(2 theta)/(t^(2))=(200 pi)/4=50 pi rads^(-2)`
`theta` in `4 sec, theta=1/2alphat^(2)=1/2(50 pi)(16)`
`=400 pi rad`
in the last `2 sec theta=400 pi-100 pi=300 pi rad`
`:.` no. of rotation =`(theta)/(2pi)=(300 pi)/(2pi)=150`