[填空题]
A cooling fan is turned off when it is ru p1mv xeqsgls9v.)q 8s h7-ce7nning at 850rev/min It turnlgsr6qp ,6*z0tr es:r)hkh p 2s 1500 revolutions before it comes to a sto hst,lr r6*)h p:0kp6s2r qzegp. (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