"base note (fundamental) as the mass moves"

Just like sliding a glass bottle neck along a string...

"Ignoring harmonics - I would bet there are several. The base note as the mass moves (though it's mass would alter it a bit), the one based on the free length above, and one based on the note below. I think we would have a glissando too as the car moves.

And then there are the sum and difference harmonics (beat frequencies) because the system is probably non-linear. And then all the harmonics of all frequencies mentioned and beat frequencies of therof."


Hmmm, Mr Glass would be delighted...