[填空题]
A small 650-gram balvovl wz*r6-9hws j7v ,l onl:yjcm. lyh ) ueg7.;y the end of a thin, light rod is rotated in a horizontal circle of radi.c:ge .);my l7juy lhyus 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. $m \cdot N$
