[填空题]
An automobile engine slows down from 45h4u1 sjq*t. c8:jjc m f.)wqxtq hoe eh*5z8a400 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. $rev$