[填空题]
A 70-cm-diameter wheel acceleratpmgh. -nh k,n-hlc0g .es u8s d0pu6vh69g(lu1k xhmqjk ; niformly about its center from 130 rpm to 280 rpm in96q6(1h gljpu0k ;8vmxduhk s 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$