[填空题]
An automobile engine slows down from 4500 rpm to 1200 rpm in 2.5 s;0z/p:r g3c,bfwyi2 brlhs9m. s(mc09 :axca jCalculate (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$