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Well, you do not like engineers but you are asking an engineering question.
Why does "sound packet" speeds away from the source?
-> What propells a wave is energy. When you generate sound waves, the particles around the source will be more energized, and the adjacent ones will not.
Why does "sound packet" propagates intact?
-> You have this doubt because you are definig the sound as a packet. But it is not. When you say a word, for example, each sound of each letter, will be generated in different positions on the time. If you say "car", the first sound generated will be the "c", so the first waves to hit the target will be the ones that forms "c", and so on.
but, not why a sound propagates away from the emitter in the first place...just that it does.
How is that darn "C" generated one moment and is suddenly the same "C" some 1100 feet away a second later?
Let me ask the question anew. If the emitter is moving only a small amount to disturb the air that is adjacent to it, why don't the repeated oscillations simply build up some level of energy at that node, which is then propagated outward as a damped wave, with the energy falling off with distance.
We get a clue from the old "rock in the water" effect but, even that assumes a simple wave that's generated and does indeed travel outward as a damped wave (intensity falling off with distance). What's more, it travels very slowly. If you make the wave more complex, you're back to the propagation of sound, as opposed to simply a wave, question again except now through water rather than air...complete with the "packet" concept.
How is that darn "C" generated one moment and is suddenly the same "C" some 1100 feet away a second later?
Sounds doesn't travel as packets nor on an "instant by instant basis" ...just think about pool balls. If you hit some balls and they hit other balls...
Dominoes explain the compression wave. The air molecules like the dominoes do not move very far, they just transfer energy by wacking into the next guy in line.
The speaker cone pushes the first batch, they push the next, etc. This explains how the energy moves but the air does not. The nature of a compression wave.
But those crashsite questions are impossible to answer for 8th grade. For example wave propagation in a circular surface (Bessel) is different from linear propagation (Dirichlet), those are more advanced than Fourier topics.
crashsite said:Again, the dominos only propagate the "ripple". The sound of the dominoes falling is the sound waves and it is the thing that somehow zips off at some 1100 feet per second. I say, "somehow" because that's the thing I don't understand.
I would like to think that if I could glean a reasonable understanding of how an airplane flies by the time I was about 13, there should be a corresponding explanation as to why sound propagates. I would hate to think that something so elementary and common is so frought with technical and mathematical gibberish that only the eggy-ist eggheads can possibly understand it.
Dominos and pool balls do a fair job of describeing the "rock-in-the-water" propagation but, that's not the propagation of sound and it's easy to describe and envision. The rock displaces some water and raises it. As the water falls it displaces the adjacent water and the ripple spreads. But, that is not sound propagation. Maybe part of the problem with understanding this thing is that elementary science tries to equate the ripples with sound waves and they are really completely different phenomena.
The SOUND of the dominoes has nothing to do with anything.
The speed of sound is due to the space between molecules. Explains why sound is faster in desnser air. Denser air allows the molecules to collide faster thus increasing the speed of sound.
Huh? How does dropping a rock in water have anything to do with the analogy for sound?
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Since the mathematical argument appears to be unpersuasive, I'll offer some additional observations which may trigger some introspective thought.
1. Sound does not propagate in a vacuum, unlike EM waves.
2. The speed of sound in a fluid medium like air or water depends on the properties of the fluid.
3. Vibrations are transmitted by a fluid, because the fluid lacks the ability to contain the motions produced by the vibrating source.
4. The vibrations are attenuated as a function of distance and are eventually reduced to unmeasureable levels.
5. A continuous sound depends on the constant addition of energy from the source to the fluid medium.
Did anyone bother to read Feynman on the subject of sound? I think it would help.
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