[填空题]
A small 650-gram ball on the end of a thin, light rod is r qqioxn )h8tk) ;i7y8rotated in a ho p p p.jqo.9hyemz84b/rizontal circle of radius 1.2 m. Calcula8o9qyb4 zh/ep pm.pj.te (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. $m \cdot N$