[填空题]
An automobile engine slows down frn6+todrq+ dc97 sxhv5om 4500 r1s8xs q 3z5k+6ogfu pqpm 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. $rev$