[填空题]
An automobile engine slows down from 4 :7b0yb gyaux4500 rpm to 1jr/tlrm- a(h9k*n : a6cmcl,k 200 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. $rev$