I've come from trying to understand how Ethernet works to studying about waves.
Question 1
So what I don't understand well is that the medium of waves return to their rest position or equilibrium after the energy leaves them. The article I read said that the particles interact with each other, and that is how waves work. Is this possible without a connection between the particles?
Now let's assume a sound wave. The first air particle is displaced and hits the one next to it. How does it know which place to return? In the website, it said the air particle (or molecule) returns to its rest position as a result of collision, but if we imagine something like the beginning of a pocket ball game, the original ball causing a disturbance only roughly returns near its original position if at all. Also the other balls would be permanently displaced, which is not the characteristics of a wave.
If the original particle knows where to return due to the void it created, couldn't other particles fill that void also, since the void isn't exactly reserved for one specific particle?
If the situation is such that the table is full of balls so that there is little space between each ball, the balls wouldn't be displaced as much, but still it can hardly be described as "assuming its original position" like a slinky coil does. I haven't tried, but I can't imagine pushing and pulling back a ball repeatedly in and out of a huge group of balls making ripples like sound waves do, or do they?
Question2
Also, if the molecules involved in making the waves can't pull each other, does that mean you can't cause sound waves by a pull force?
Question 3
Is the difference between creating a puff of air and creating a sound wave just how short and abrupt the disturbance is, like when snapping a towel?
Best Answer
In an elastic solid, particles return to their equilibrium position after the sound wave has passed: because they are attached to each other they have a definite "sense of place".
Air molecules don't have a fixed position: the jostle around, and the average effect of their motion is experienced as pressure (number of particles hitting an area multiplied by their change of momentum normal to the surface = force per area = pressure).
Now when you increase density, you increase the number of molecules per unit volume; this increases the number that hit a unit area per unit time, and thus the pressure. But since the molecules "in the next slab of air over" don't have an equally high pressure, more molecules will move from the high pressure area to the low pressure area than vice versa, so the high pressure "wave" moves on. If you lower the density in a region temporarily, the opposite happens: molecules from adjacent higher pressure areas will move in "to fill the void".
All this is possible because, if you imagine a box full of air with an imaginary plane running down the middle, a roughly equal number of molecules will move across the plane from left to right, and from right to left, every second. If you start with one color of gas on one side of the membrane, and another color of gas on the other, very quickly the two will mix - this is called diffusion.
All of which is a long winded way of saying: there is a microscopic picture of molecules moving that explains pressure, diffusion, and sound waves. This picture tells us molecules have no fixed position; but they do have a tendency to move from high pressure to low pressure.
I also recommend reading the question/answer that I wrote previously. It has a possibly helpful picture.