[填空题]
A cooling fan is turne/ qlz(gfnkb/h; : gpk1d off when it is runnitr t2aqb9(b 7ung at 850rev/min It turns 1500 revolutib2r (tqb at7u9ons before 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