[填空题]
A small 650-gram ball on the e-y ji )duf;1-1hgqtmond of a thin, light rod is rr8 32 02knlfyk8si z l4,zzathotated in a horizontal circl2 2flhz zzky8an3kl,0 itr4s8e 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. $m \cdot N$