[填空题]
A cooling fan is turned off when it is running at 850rev/mj3tvs,*qtopcy.)a;b* : u: *qbb xigbin It turnl7g 6 em0sxrn nkqlgf/n:tp/24o,j 9xs 1500 revolutions before it com ok/enx4rg7 0pts :9llmn6xf/,j2 gnqes 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