[填空题]
A cooling fan is turned off when it7lxt*iay8 n*2ix ry g8 is,e j-2n h2per/r;eysy running at 850rev/min It turns 1500 revolutions bef ;pj/r2er, ehny-yse2ore 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