[填空题]
An automobile engine -/c ;4 *ztjgtuvep1tr v4l6xjslows down from 4500emtu8) l, 9zgbww0f7(6qv u wo rpm to 1200 rpm 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. $rev$