I would like to understand exactly how to principle of superposition works. I don’t think its so simple that you could imagine as first. A mechanical wave doesn’t need a physical movement to spread thorough a medium, and it can not be stopped by physically stopping the movement of some of the oscillators that make up the medium it travels through. Let me clarify what I mean with the help of an example. You start a mechanical transversal wave in a feather by pulling one end of the feather to the side and back again. This will creates a mechanical wave that travels with the same appearance through the feather.. but some part of the feather is physically unmoveable, while the rest of the feather after that is moveable, what will happen? I think that the mechanical wave can pass through the unmoveable part to regain its movement on the other side of the obstacle. If this is not the case, just don’t get it. Because if mechanical waves only spread through physical movement of the oscillators, then why cant a much bitter mechanical wave simply permanently destroys a smaller when they pass each other with opposite peaks? I mean it should simply “kill” the driving force behind it at the expense of loosing some of its own driving force, but that’s not what happens. So how does it work anyway? How does the mechanical waves spred without actual movement of the oscillators ?