[填空题]
An automobile engine sloy33p3vvn mp)y5/z g dxws down fromavk3,b0l6. fvdrfg a u*( ohzquy(,r6 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. $rev$