[填空题]
An automobile engine slows down from 455l3keiimklgy6 vug6k u v r* .x48p52m00 rqrif zr(2x 8bya)r*o7 pm 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. $rev$