A small bead of mass m is constrained to move along a frictionless track as shown. The track consists of a semicircular portion of radius R followed by a straight part. At the end of the straight portion there is a horizontal spring of spring constant k attached to a fixed support. At the top of the circular portion of the track, the bead is pushed with an unknown speed vo. The bead comes momentarily to rest after compressing the spring a distance d. The magnitude of the acceleration due to the gravitational force is g.
What is the magnitude of the normal force exerted by the track on the bead at the point A, a height R above the base of the track? Express your answer in terms of m, k, R, d, and g but not in terms of vo.