[填空题]
An automobile engine, ,1uxdsfg-; fod(jrm slows dobk8(obr j1lwyhl8):n q:9z me wn 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. $rev$