# Is gravitational Force is damping force in vertical mass-spring system of constant k in Simple Harmonic motion

When a block of mass m is suspended by vertical spring system,it for sure perform SHM in the absence of damping force,only force which act on the system is internal which is -kx, where k is spring constant,so well so good but there is external force on the system which is gravitational force, which is mg (where g is acceleration due to gravity, for good approximation near earth's surface) which always there on the system towards vertically downward direction.

so what is this force {gravitational force} we should consider of, is it applied force on system to have forced oscillation or damping force ?

If it is applied force then it must be periodic and varies as time passes,but it isn't. A follow up question is that is applied force can be constant throughout to have forced oscillation ? ,if that so,then sorry for the above part !! Then another question arises, On considering this fact as mg act always vertically downwards,Then oscillation with constant amplitude therefore,not sustained,and this situation only arises when damping force is there,but we aren't consider this force to be damping one ?

If it is damped force then it must oppose the velocity for all the time,but it opposes the velocity for sometime and increase the velocity in some part of time.

so if we consider gravitational force then what this force actually doing is in SHM ???

sorry for the lack of -kx sign and upward motion in the diagram