[填空题]
An automobile engine slows down from 4500 rpm to n/-3q fsa oh9ebsp;f9vg 76 wg1200 rpm in 2.5 s. Calculyxw+y8w -b if:6rvyc 7ate (a) its angular acceleration, assumed constant, $rad/s^2$ (b) the total number of revolutions the engine makes in this time. $rev$