[填空题]
A cooling fan is turned off when it is running at 850rev/min It tu-gc wecl1bw8/ rns 1500 rdh4*4e ctib (mxw04c: nqu7beevolutions before it4:d * (bn x7cm w4e4uih0cqebt 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