Jiff,
Remember the analogy where a boy stands on a boat and throws a rock aftward, and the boy/boat system moves forward?
What happens if the boy does everything but forgets to let go of the rock? The boy/boat system moves forward, then moves aft as the rock moves in its arc. The boat oscillates back and forth, but the CG of the total system goes nowhere.
Your elaborate system is exactly that, and even if you plot forces and phases until you turn a bit purple, the net result for a set of masses that is still attached is that all the forces must sum back to zero net force.
In your system, the boy never tosses the rock, Jiff.
Last edited by NickLappos; 12th July 2007 at 09:23.