[填空题]
A small 650-gram ball on g(8 )7l qlgrk7rh.-nyigw)d tthe end of a thin,llbwd.()trym:t0ug *3 6vdmx *b5pw a light rod is rotated in a horizontal circle of radius 1.2 y umb*p:.w ma)dtw 0b3*tdl6r (5 lvxgm. 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. $m \cdot N$