[填空题]
A small 650-gram ball on t4aee/3 k/byl xlnb7 7ohe end of a thin, light rodv92m,*x8 fjft xwnz2w is rotated in a horizontal circle 89f * zx2 ,vfnwwmj2txof 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. $m \cdot N$