[填空题]
A small 650-gram ball on the end of a thidtjm **obnr*t+ kv)3;7cdo v; bwu4 zhn, lr,:bzgxo5tse s sw g+ *7;0cubight rod is rotated in a horizontal circle of radius :0w grec,+o;*tsxsz5g su 7b b1.2 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. $m \cdot N$