[填空题]
A grinding wheel is ap7 8 s+gngo;br uniform cylinder with a radius of 8.50 cm 3 (n)lrxujowdu a-7y, and a mass of 0.580nrj- l),od3x7(uawy u 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。 $m \cdot N$