[填空题]
An automobile engine slo(tuby/ rcqc7le.cjb : 5i17gkws do g/e m*z*ad s kuvos77 bq +no,x6/gosmi45s+own from 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. $rev$