The frequency of the fan is,
f=120rpm60=2hertz
Angular speed will be,
ω=2π×f=2π×2
=4πrad/sec
A fan initially rotating at 60 rad/sec clockwise accelerates and aquires an angular velocity of 110 rad/sec clockwise. If the angular acceleration of fan is constant and it takes 2 sec to change its angular velocity, find the angular acceleration of the fan.