I would like to clarify my basics there is a spring fixed at one end and have a mass at the other end. Call this as system one I have a mass kept alone. Call this as system two If i apply a force to system two for one second the mass will accelerate in one second to some velocity depending upon the force and the mass If i apply a force to system one for the same one second the mass will accelerate to some velocity in one second. Say it accelerates at 1m/s per second. So during this one second displacement occurs at the end of the spring(mass attached end) to a value of 1m. So the spring now exerts a reaction force proportional to this distance of 1m. If the reaction force is not equal to the applied force then the net force will continue to accelerate the mass. Now after two seconds if this reaction force equals the net force the mass comes to rest. This stopping of the mass can occur after two seconds or even after hundred seconds. How can i find this time? Can i find the border line difference between Statics and dynamics from the above discussion?