[填空题]
A 70-cm-diameter wheel accelerates u;1bz/w p 0zpnzniformlm)novh,p.in :a;d u/8m:b i pny about its center from 130 rpm to 280 rpm.pdo: mni p;bu n)h/:vmn,i8a 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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$