The 2-kg follower is attached to the end of a light telescopic rod that is pivoted at o. the follower is pressed against a frictionless spiral surface by a spring of stiffness k = 100 n/m and free length l0 = 1 m. the equation of the spiral, which lies in the horizontal plane, is r = b?/2?, where b = 0.4m and ? is in radians. immediately after the rod is released from rest in position oa, determine (a) the angular acceleration � ? of the rod; and (b) the contact force between the follower and the spiral surface.