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Question about vibration

  1. Jan 5, 2008 #1
    If two metal objects hit, do the objects have to vibrate to make a sound? Or can the air itself vibrate with the sound?
  2. jcsd
  3. Jan 5, 2008 #2
    Is there was no air, could you hear the metal objects when they hit?
  4. Jan 5, 2008 #3


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    Staff Emeritus
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    If the objects did not vibrate, what would cause the air to vibrate?
  5. Jan 5, 2008 #4
    I don't know. I thought sound was the result of potential energy being released as kinetic energy (I don't know much about this, bear with my ignorance :| ). So one of the metal objects would have to vibrate for there to be sound?
  6. Jan 5, 2008 #5
    The sound is a wave travelling in the air. When the objects hit they beame sourses of these waves. If there is a medium for these waves to travel (i.e. the air) they will reach at your ears and you will hear the sound.
  7. Jan 5, 2008 #6


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    The collision itself will push air, creating a sound like thunder or clapping hands. The objects themselves need not vibrate.
  8. Jan 5, 2008 #7
    Oh, okay. That's what I was wondering. Someone told me that one of the objects would have to vibrate for there to be sound, but I figured the air alone would do it. A thought, is this how things like lightning make sound?
  9. Jan 5, 2008 #8


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    In a way. Thunder (the sound of lightning) is basically the aftermath of an explosion. A lightning bolt is in the millions of degrees, which superheats the surrounding air much as a high explosive such as C-4 would. That overpressure radiates in all directions from the path of the bolt, so the inverse square law applies to the intensity where it's heard.
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