[填空题]
A cooling fan is turned off when it is running at 850rev/min It turns 1500 nu1d;+g,*y tsejh l h;revo9wwwi- .x zi9l zjie(.lutions before it comilw -e.i99.(wixwjzz es 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