Here is my question, hope someone can help. Q: You attach a mass m on a spring with a spring constant k. You then lower the mass so it hangs on the spring in equilibrium. a) If you pull the mass down a distance y, so its below the equilibrium position, then let go, the mass will bounce up and down. Draw the force diagram for the mass just after you let go. b)At this instant, what is the net force on the mass? Is the force upwards or downwards? and is the force linear with distance y? c)Will the periodic bouncing of the mass be SHM? For a), the forces acting on the mass would be Fs which points upward, and mg which points downward. What am I missing? For b) would the net force just be F= Fg + Fs ? The spring force is upwards and the force of gravity is downards, so the net force is 0?? I am not sure if it is linear. For c) yes it will be SHM, because the net force is proportional to the displacement from the equilibrium point? Thanks for the help!!!