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Some Questions on Sound

  1. Jan 30, 2005 #1
    how come different sounds are made when you hit different objects together, when in reality, the two objects aren't even touching (due to the repulsion of the electrons that make up the objects). and what is a sound wave? it cant just be the movement of air because then we would here different sounds all the time when it was windy, right?

    also, is heat created due to the movement of atoms, or the vibrations of atoms? if its just movement, wouldn't windy days be hotter than they are?

    these are probably really stupid questions, but i was just curious.
  2. jcsd
  3. Jan 30, 2005 #2
    Well the fields 'touch', this is enough to let the objects and by this the air vibrate.

    Both sound and heat are the vibration of atoms. Sound propagtes by means of a longitudinal (in air) wave. This means the air contracts yielding a locally larger pressure, than expands, in a forward propagating manner. So the wind you mention is not in the organised form, and with large pressure differences, we experience from sound.

    If you do the calulations you will find the speed of these vibrations associated with thermal energy much faster than any storm.
  4. Jan 30, 2005 #3
    Although * technically * the objects arent touching, they are as good as touching for all purposes. The space between one object and the other when we see it as 'touching' is infinitesmally small. In any case, the force from one object is still transfered to the other. IE, bang a hammer on some wood, even though the wood and hammer molocules never actually touch, the hammer still 'pushes' the wood, because the magnetic fields of the atoms are pushing on eachother.

    You may be right, wind may alter sound to a degree, but really, sound moves much much faster than wind, so the sound should zoom right through a windstream before it changes much, making it harder for wind to alter sound very much.

    I would say that wind does transfer some heat energy to you, but very little, and the winds cooling effects on the skin greatly outweight the heating effects. As to why wind doesn't transfer alot of heat energy, I would have to guess that due to the relativly slow speed of wind (from 1-20 mph), there simply isn't enough kinetic energy in this to make that big of a difference, due to the speed and also mabye the low density of air. Someone should be able to answer this one better.
    Last edited: Jan 30, 2005
  5. Jan 31, 2005 #4
    If that is not touching, nothing is, so you might as well call it "touching". Specifying what Jake said, repulsion is not due to magnetic fields or surface electrons, it is due to the object's entire electric field framework of both nuclei and electrons.

    The difference between a sound wave and wind is that wind is not a wave, or rather, it is an extremely low-frequency wave. If wind went left and right really quickly, it would make your ear drum shake, and you would have noise.

    In a wind, all atoms travel in the same general direction. In a hot gas, they don't. That is much of the difference.
  6. Jan 31, 2005 #5
    I am a front of house live sound engineer. Wind definitely affects me on a daily basis when working outdoor jobs. It gets really bad in larger venues (20,000 seaters or more). You can hear the high end (5kHz and up) literally comb filtering as it makes it's way through the atmosphere.
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