[填空题]
An automobile engine slowshj 3;e2b1hby)l9y e br dok+ -u xf06j*s47vhmxn7kx iljwn from 4500 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. $rev$