[填空题]
An automobile engine slows down from 4500 rpm to rxs-jqy zz), -sh;w7 vhe j85w1200 rpm in 2.5 s. Cab ufhq:6oa/w rq a7gv57280 ,twrfjeilculate (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$