[填空题]
A small 650-gram ball on the end of a thin, light rod is rotated in aez- 4,asslu- w8ofkl o)u+xzdz-x24n h f3et 1 horizontal circle ofzhk43 e xz)-o81 x+od fltf2nu radius 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. $m \cdot N$