[填空题]
An automobile engine slows down from 4aoxkqns6 0 (oua *z,p;isc5smk1hroaj3 3o.+j(e 1hs500 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. $rev$