[填空题]
An automobile engine .qgvav57r(k-/yi t ofslows down from 4500 rpm t j/io xs:a)x lls5pjyc(u.0eg)*4lxe o 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. $rev$