[填空题]
A 70-cm-diameter wheel accelera x4 6po;yv *l,kbeaj/dt gr1 1aif-czii0h (6dies uniformly about its center from 130 rpm to 280 r6ia( r f0hi1i d1-gzcipm 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$