[填空题]
A small 650-gram ballllo r/n:.(m2 f9zhqjrg*v c2is mn/c2mf*m6r mc gk,+ on the end of a thin, light rod is rotated in a horizontal circlem*2rc m+,6cmmg ks/f n 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. $m \cdot N$