[填空题]
An automobile engine slows down from 4500 rpm to 1200 rpm in 2.5 sh ttw* t5zt3kb.aj19c . Calculatjgoo-,nxh*mm i 3ki9 4e (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$