[填空题]
An automobile engine sl/oqt z,5girv) ows down from 4500 rpm*: u:j72ob g-w z axxs-tnjm5o 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. $rev$