[填空题]
A 70-cm-diameter whee*8 kcr1u1ji yrl ac1 2tmsx0s:1hmil0js tcelerates uniformly about its center from 130 rpm to 280 rpm i:1s0iml j01mxsth2s t 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$