[填空题]
An automobile engine slows down from)sgw;dc illdxi2u0 -59pu5x c(4 j7iz)0b5x ymvztm i4500 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. $rev$