[填空题]
A small 650-gram ball on5 h lh5tpnu) 4wu *8x9a:qhcam the eda)an-4x/sunllnyhyt 3hxh7 x :1j,:ssui 34nd of a thin, light rod is rotated in a horizontal shniansh7ujdnxly-: /3u14x h y4 lt: x,3)sacircle 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. $m \cdot N$