[填空题]
A cooling fan is turnedct 9b3xv uo10o-*sq nurg mh0e9rz9,nys1t,9k:ep ri p+ 0pw 2px. ,d 7f;bxnfyt6buloff when it is running at 850rev/min It turns 1500 revolutions before it xxe6uk+ 1tpppn7 ,ybsbp ,;w 09.id ff:2ytlrcomes 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