[填空题]
A cooling fan is turned off when it 23)zro( mgv l 70pdc 16geitypis running at 850rev/min It 6o. :yan7ase /xy19k:bf b iwxturns 1500 revolutions before itx6 y7o b1:saanxibk:eyf/w .9 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