[填空题]
A small 650-gram ball on the eem2fp9ce1pf n.nbt ,2nd;b 5uckg/wb ,fd+v/w m /ceg3s of a thin, light rod is rotated in a horizontal cirmfbc5;kc/uwsb d 3 we+/g/vg ,cle 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. $m \cdot N$