[填空题]
A cooling fan is turned oflusd.e6,(+1lawt hbb f when it is rufk4:.fp gy4qcx2m5 ydn c+c7+ r6ldwx nning at 850rev/min It turns 1500 revolutions before it codg65q ccy w :.2 +4yxfkd4x nf7+lprcmmes 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