18 8 Olympic Champion Shaun White practices at his personal half-pipe, a large semi-cylindrical surface kept frictionless with a smooth layer of ice. Shaun remains crouched on his snowboard, and releases from rest at point A. The resulting ride passes downward from A, follows the surface horizontally through B and coasts upwards through C to stop at D. (Then, it could oscillate forever, or until the ice melts, if we ignore air resistance). Using his mind and not his muscles, Shaun correctly calculates that at point "C" the magnitude of the total force exerted on him by the ice is exactly 40% of what it is at point "B". Calculate the value of the angle 0. Answer in degrees. (a) 21.8 (b) 23.6 (c) 28.2 (d) 36.0 A (e) 66.4 B R Ꮎ D

Fig: 1