[填空题]
A small 650-gram ball on 3ylj(e0tbi4lg tz 4l8the end of a thin, light rod is rotate+l)*p.g xtjnl d in a horizontal circle of radius 1.2 m. Calc*jpl)+nxg.t lulate (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. $m \cdot N$