[填空题]
A small 650-gram ball on the end of a thin, lig /+yv xycvq8p l-mx*3yht rod is*xgnop );wb y8 7gf5sbzf0 gm) rotated in a horizontal circleopzb7) ; *ffy5nw bmxggg08)s of 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. $m \cdot N$