[填空题]
An automobile engine slowonli0cn7cu.:wt q -t*t0lby5s down fromu04ma1h43( b wzzbbe-ygts5;m4t hje 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. $rev$