[填空题]
A 70-cm-diameter wheel accelerates uniforjf dik/9)2jbyb7h:vjg2nu12q2 m gx nmly abjme ;fp dt90jv/p ,*tqout its center from 130 rpm to 28jd0; ,*ptvqme9 t/pjf0 rpm in 4.0 s. Determine (a) its angular acceleration,$\approx$ $rad/s^2$(Round to one decimal places) (b) the radial and tangential components of the linear acceleration of a point on the edge of the wheel 2.0 s after it has started accelerating. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$