  At every points of a static equilibrium system, the net force is zero. If one
of the composite forces of this system is disappeared, it is no more in
equilibrium and this effect of absence spreads through the system with a finite
velocity. So it takes finite time before this absence is manifest at the other
points. A frequently asked question may describe this situation well. ``If the
Sun disappears abruptly, does this affect us instantly?" In this question
centripetal force due to the gravity of the Sun does not disappear
simultaneously all over the place, so the Earth sustains its elliptical motion
for a while. As this example shows, it is a well known fact that the force does
spread with a finite velocity. But for the specific problems it is sometimes
not easy to notice this property of the force. To help this, we consider the
motion of a falling spring and a falling catenary. We study the conceptual
aspects of these motions and apply it to the experimental data. A minimal
theoretical background is also treated. For the future, we anticipate that this
work would be useful for enhancing the concept of wave motion.
