[填空题]
A small 650-gram balxah+1s n:d. pxm0y8nsj e3q; rl on the e5txs,7wrste*b:as. bnd of a thin, light rod is rotated in a horizontal circle of radius 1.2 m. Calcul b5a xr7sst:,*.sewb tate (a) the moment of inertia of the ball about the center of the circle, $kg \cdot m^2$ (b) the torque needed to keep the ball rotating at constant angular velocity if air resistance exerts a force of 0.020 N on the ball. Ignore the rod’s moment of inertia and air resistance. $m \cdot N$