[填空题]
A small 650-gram ball on the end of a thin, light rod is rotated in/fovn29j,0 e +znw hby a9)6;yca jf(qrg) lnbh qn. (qtf9 a;dj horizontal ctcq a g() 9fhjlq 9b(;nrad6 y;)njq.fircle 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. $m \cdot N$