[填空题]
A small 650-gram ball on twu,7s/2dwi.fvglp/ s f 6jmk5he end of a thin, light rod is rotated in a horizonqrip -r0tlm dze0-0) rtal circle of radius 1.2 m. Cz0 )rlp- im dqtrre-00alculate (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. $m \cdot N$