[填空题]
A 70-cm-diameter wheel accelerates uniformly about its cen(85: lvnqsy q(wa0q vrter from +u ck*xcan2ol xl;5(u 130 rpm to 280 rpm in 4.0 s. Determineuc2;xk+n( xac 5*oull (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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$