[填空题]
A grinding wheel is a uniform cyli ngl9x 9ej5z.rnder with a radius u(dz8xjpp vg+s:h41p of 8.50 cm and a mass of 0.580 kgz 1 (uhdgpx +sp:4v8jp. 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。 $m \cdot N$