I have some basic question about spring force. The anchor position for spring is its equlibrium position. As the spring is stretched, when released, it is expected that it should come back to its equilibrim position. But I found when less force is applied, the new equilibrium position is a bit far from the original position of rest. The more force is applied, it comes closer to the original equilibrium position. Could any one explain this behaviour with mathematics. For a certain amount force if I always want the spring to be back in its original equilibrium position, what do I need to do? Thanks every body in advance.