A spring AB of constant k is attached to a support A and to a collar of mass m. The undeformed length of the spring is l. Knowing that the collar is released from rest at x = and neglecting friction between the collar and the horizontal rod, determine the magnitude of the velocity of the collar as it passes through point C. Can anyone explain how to go about solving this problem. the answers supplied are for a problem in the following chapter with the same figure. The question in the following chapter states "A spring AB of constant k is attached to a support A and to a collar of mass m. The undeformed length of the spring is l. Knowing that the collar is released from rest at x = and neglecting friction between the collar and the horizontal rod, determine the magnitude of the velocity of the collar as it passes through point C."