[填空题]
A small 650-gram ball on the eo,u.i zq k:wh3-irluj:jz 2.rnd of a thin, light rod is rotated in a hori l 5uy267fmvudzontalml6u fd75v2yu circle of 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. $m \cdot N$