I think what PeteM is trying to state, which would be getting back to first principles and a simple approach, is that the sum of the Forces equals Zero(F(total) = 0). An increase of transverse forces could be attenuated or dampened by the strength of the tube while an increase in longitudinal down barrel(Fb+) force due to a higher velocity would be subject to a higher negative/reverse force depending on the friction factor(like a -kx spring factor) down the tube.

Also I failed to note that due to the geometry of the tube and if the tube is concentric the reflected/attenuated wave/vector collides with another reflected/attenuated wave at the center of the tube and cancels each other similar to a standing wave. If one of the transverse waves isn't reflected or only partially reflected from a weakened portion of the tube then the weakened portion experiences the opposite reflected wave which was to be cancelled.

Kind Regards,

Raimey
rse

Last edited by ellenbr; 09/03/08 09:13 PM.