[填空题]
A grinding wheel is a uniform cv jungs5(cs+07+z lor ylinder with a radius of 8.50 cm and a mass of 48lyr09t ifxz0.580 kg. Calcu9zl0i t 4xyrf8late (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。 $m \cdot N$