[填空题]
An automobile engine slows down from 45y hae*fd byf.//- ea2g00 rpm to 1200 rp e t,,g4w-qe7g b+0i w1ovtmsgm in 2.5 s. Calculate (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$