[填空题]
A 70-cm-diameter wheel 6*++8 a k v.apfft nz9guug.mhaccelerates uniformly about its center fc ztgup nlx 0.0 4pab5,mt6m4rrom 130 rpm to 280 rpm in 4.0 s. Dub5axt0 rz4gmp p.c,tm64n0letermine (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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$