[填空题]
A grinding wheel is a uniform cylinder wi-(d gv 5x-wyskbar4z- th a radius e+fciw ;zr2 q vn-/h.jof 8.50 cm and a mass of 0.580e r-+.zincw j/v;fq h2 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。 $m \cdot N$