[填空题]
A small 650-gram ball on the end of a thin, q edt4k7j c(d,lighto;eis ,7qp q3hxgler4 9*o rbd) yln*( rod is rotated in a horizontal circle of radius 1.2 m. Calculat 4eosriyr xq,on (lleg3b9hq7d **; p)e (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. $m \cdot N$