A grindstone Is found to have a angular speed of 150 rpm, 10s after starting from rest. The angular acceleration of the grindstone is

Options

A. `(pi)/(3)`
B. `(pi)/(2)`
C. `(pi)/(6)`
D. `(pi)/(5)`

Answer

B

Explanation

`omega_(1)=0`starting from the rest. `omega_(2)=(2pixx150)/60rads^(-1)``rArr=(2pixx150)/(60)=5pirads^(-1)`Time `Deltat=10s``therefore`Angular acceleration,
`alpha=(omega^(2)-omega^(1))/(Deltat)=(5pi -0)/(10)=pi/2rads^(-2)`