[填空题]
A grinding wheel is a uniform cylinder with a radiup y(07ltp7yrhs of 8.sg.j, :v.srp hy2 t/ag50 cm and a mass of 0.58s gs2. va:,h .rtp/ygj0 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。 $m \cdot N$