[填空题]
A cooling fan is turned off when i x:.5 zorxm*ait is running a8+8zhfb ey(r or9d( dlt 850rev/min It turns 1500 revolutions before it comes to a8l 8f(dz+9ybrdro ( eh 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