The 0.2 kg ball is moved along the surface of the semi-cylinder with rotating rod OA in a vertical plane. The semi-cylinder has a radius, rc = 0.5 m and the radial position of the ball is described by the equation r = cos (6) m. If the arm rotates with an angular position e(t) = (0.1t2) radians, where t is in seconds, determine the following: a) The force that rod OA imparts on the ball at 2 seconds. b) Determine the normal force from the surface of the semi-cylinder at 2 seconds.