[填空题]
A grinding wheel is a uniform cylinder wix o02f)4ym2r:9lc fxkf yig1 hth a g4.nwzwh a+/rj :o.fnradius of 8.50 cm and a mass of 0.5.jrza h+won:nw.g /f4 80 kg. Calculate (a) its moment of inertia about its center, $\approx$ $kg \cdot m^2$ (b) the applied torque needed to accelerate it from rest to 1500 rpm in 5.00 s if it is known to slow down from 1500 rpm to rest in 55.0 s。 $m \cdot N$