a thin-walled, hollow sphere of mass m and radius r is free to rotate around a vertical shaft that passes through the center of the sphere. initially, the sphere is at rest. a small ball of clay of the same mass m moving horizontally at speed v grazes the surface of the sphere at its equator. after grazing the surface, the ball of clay is moving at speed v/2 . what is the angular momentum of the ball of clay about the shaft before it grazes the surface? express your answer in terms of the variables
