Harmonic Oscillators, a general conceptual question, help please understanding?

[jcfor3ver]

1)So I will describe my lab situation first, then ask my main questions. In my physics class we had an inclined air track, with 5 masses (carts) and 5 springs connected in between them. We turn on the air track to replicate a mostly 'frictionless' surface.

Now we did several trials writing down our observations and adding more masses to the carts and so forth.
My main question is what exactly does 'coupling' mean? I know we are looking at a coupled harmonic oscillation system. But as far as energy propagation through the system and wave velocity I do not know how to describe what I saw in these terms.
I'll add a little knowledge to what we saw. It seemed that the amplitude of the lowest elevated cart was the biggest. I know that energy propagation is transferred through the system because it seems like a very tiny 'wave' was passed through all the carts, and once it reached the end would turn around and comeback the other way.

3) My attempt at the solution is that since the track is elevated and at an inclines we are dealing with KE, Potential spring energy, and gravitational potential energy. I think the amplitude of the bottom cart is the smalled because it is not holding all of the masses like the top cart (which spring is attached to the end (or top) of the track) and therefore has the least grav pot energy. Which means that if energy is idealy conserved then it will have the most kinetic energy at the bottom. As far as wave velocity is concerned, would the wave velocity be the same equation as that of a wave along a string?

But I'll restate my main questions, how is energy being transferred/transformed? How is the energy being propagated? What does 'coupling' mean? And what would increase this 'coupling'? As far as wave velocity is concerned, would the wave velocity be the same equation as that of a wave along a string? I guess some other knowledge on coupled harmonic oscillators would be helpful too because I am just confused on this concept, and looking things up online hasn't helped me a lot.

 

[Redbelly98]

"Coupling" means that adjacent masses exert a force on each other (because of the spring).

As for how energy is transferred/transformed or propagated, think about it this way: if the masses are initially at rest, and then you were to give a kick or jolt to start just one of them moving, what would soon happen to the other masses, and what physically causes that to happen?

I'm not quite sure what to make of the larger amplitude for the bottom mass. "Conservation of energy" applies to the total energy, added up for all the masses together. It doesn't say that each mass has the same energy as the others, so I wouldn't necessarily conclude that the one with the lowest potential must have the highest kinetic energy. Perhaps the fact that the lowest mass is a "free end" (as opposed to a fixed end) has something to do with it.