[填空题]
A 70-cm-diameter wheel accelerates unifz.ukpd)0dd skw r6m96ormly about its c j(,z r.lzkqn7enter from 130 rpm to 280 rpm iqk. rzl7n,jz( n 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$