A ball of radius R and mass m is magically put inside a thin shell of the same mass and radius 2 R. The system is at rest on a horizontal frictionless surface initially. When the ball is, again magically, released inside the shell, it sloshes around in the shell and eventually stops at the bottom of the shell. How far does the shell move from its initial contact point with the surface?
Answer Choices
A. R.
B. R / 2 .
C. R / 4.
D. 3 R / 8.
E. R / 8
