A small sphere , with a radius r = 1.52cm and a mass m = 13.8g rolls without slipping on the inside of a large fixed hemispherical bowel of radius R = 18.6cm and a vertical axis of symmetry. The small sphere starts at the top from rest . What normal force does it exert on the hemisphere at the bottom? Hint: first express its kinetic energy at the bottom in terms of its linear velocity there.