[填空题]
A 70-cm-diameter wheel acce5u n dogr:s0a+8oss .blerat7ii 9wt uvzkp0ob, n s)2:uo/ses uniformly about its center from 130 rpm to 280 rpso itv:uw07i2 9 bkzs,/ pno)um 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$