[填空题]
A cooling fan is turnedprx 6o2gy41sg off whenohrcpe1 .,(7rh3q n q9janzu1 it is running at 850rev/min It turns 1500 revolutions befo9u n 1q1 jr7.e,ncrqo(pah3hz re it comes to a 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