[填空题]
A 70-cm-diameter wheel accelerates uniformly about its ch9 9(; ,x3zhuw:v iwwpp k3kaven/x 7uc ;u0lnz* e/xdtbter from 130 rpm to 280 rpm in 4.0 s. Deterxcu7 dzu*ltnb0;e/x/ mine (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. $a_R$ $m/s^2$ $a_{tan}$ $m/s^2$