Ball within a shell. In Fig. a ball of mass m and radius R is placed inside a spheri- cal shell of the same mass m and inner radius 2R. The combination is at rest on a floor. The ball is released, rolls back and forth inside the shell, and finally comes to rest at the bot- R 2R X tom. What is the horizontal displacement d of the shell during this process?

Ball within a shell. In Fig. a ball of mass m and radius R is placed inside a spheri- cal shell of the same mass m and inner radius 2R. The combination is at rest on a floor. The ball is released, rolls back and forth inside the shell, and finally comes to rest at the bot- R 2R X tom. What is the horizontal displacement d of the shell during this process?