[填空题]
An automobile engine slows down u0ec rbkuv/b ygx78hp0c/s6 :from 4500 rpm to 1e -mkf0/ s/swg200 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. $rev$