[填空题]
An automobile engine slows down from 4500 rpm to 1200 rpm in 2fbf4 l1cg weqax868;;+t: jlc go8wgp.5 s. Calc ft98cqjw2n t+ulate (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$