A Phys. Teacher SOS thread is on a "cheap" * wave machine (the Bell Labs. type) made of skewers, gummy bears, and masking tape.** One poster wrote,
"He also didn't focus on the inversion that took place when the pulse reached the end. Suggest that you could produce more defined and shorter pulses that would show this phenomenon pretty clearly."
Which I think clearly wrong***. On reflection the up end of the skewers is still up. This confirms the theory regarding free and clamped ends of the machine. There does appear to be some loss in amplitude. I haven't carefully looked to see if it's expectedly, at the end. It is generally a rather low Q resonator.
So my question is must a appropriately partially free (passive) end be completely absorbing. i.e. one which results in neither inversion or non-inversion. Intuitively if neither occurs there is no pulse of wave reflected. This would be easily done by clamping the last skewer to a dash pot, but is this the only method (type or principle)?