[填空题]
A small 650-gram ball on the en*8r oy*eoz3+ww0t qv65h fhnxd od.z+ (wk+ jzli :ij3zqf a thin, light rod is rotated in a horizontal circle of radiulkq ijdwzzi+3zj:+(.s 1.2 m. Calculate (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. $m \cdot N$