[填空题]
A cooling fan is turned o73tsif m 6e0w,ajw r1uff when it is run,nbl9zjk5ogl6( y g-zlz gh)5ning at 850rev/min It turns 1500 revolutions before it comes to anyg-6lbzgh(,5ozk l ) 9zgj5l stop. (a) What was the fan’s angular acceleration, assumed constant? $\frac{rad}{s^2}$ (b) How long did it take the fan to come to a complete stop? s