[填空题]
An automobile engine slows down from 4500 rpm to klc mf*h c)63efvw+0lela )2j 1200 ,yj6abf,n j*grpm 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. $rev$