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Why ripple effect doesn't happen on air as it does on water?

  1. May 10, 2014 #1
    Hi everyone,
    I am wondering why a single disturbance can cause ripple on water surface but the same is not true when sound wave is made. When air is disturbed, only one pulse is made in one time. What set the difference?
    Thanks in advance.
     
  2. jcsd
  3. May 10, 2014 #2

    Nugatory

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    There are multiple pulses in air as well, but our ears don't pick up individual pulses. If the pulses are close together, we perceive them as a high-pitched sound; if they're a bit farther apart we hear them as a lower-pitched sound.
     
  4. May 10, 2014 #3

    UltrafastPED

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    Sound is transmitted by pressure waves - the air is slightly compressed by the "speaker", then relaxes - and the pressure waves move outward from the source, decreasing in intensity as they move outwards.

    You may not see these "ripples" in the air, but you can hear them - and the ear is a complex device which can pick up quite faint sounds, though bats and owls have better hearing.

    The ripples you see for water are a surface effect - but we are immersed in the air, so for us there is no surface ripple for sound. But you can indeed see it for very strong sound waves - both on a water surface, a drum head, or worst of all - in the after effects of an earthquake.
     
  5. May 10, 2014 #4
    Thanks for your reply, PED.
    Now I think of that it's true when immersed in a body of water, one can only produce one pulse a time. I think ripples can only exist on surfaces or boundaries between different medium.
     
  6. May 10, 2014 #5
    You can think whatever you want. That doesn't make it true. It's possible to produce a single ripple wave on either surface or bulk waves, but that's usually not what happens.
     
  7. May 10, 2014 #6
  8. May 10, 2014 #7
    Hi dauto, thanks for replying.
    Can you show me how to produce a single ripple water wave on the surface? Why do we usually have it like it is then? I'd appreciate it if you can tell me more details.

    That's cool. Thanks man. Then how about other waves, do they act the same?
     
  9. May 10, 2014 #8
    What other waves do you refer to?
     
  10. May 10, 2014 #9

    sophiecentaur

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    Bottom line is that exactly the same Maths describes all of these phenomena. A disturbance spreads out in all directions, whether it's a stone or a 'bang'.
    Imo, the relative difference between the two things is a matter of Human Perception and the timescales involved. 'Ripples' spread out from any sound source and they bounce off walls and obstacles. That's all in three Dimensions, rather than the two Dimensions of a water surface. The waves are longitudinal, rather than surface waves but a single pulse in both cases behaves pretty much the same (once you scale the times appropriately).
    Aamof, sound tends to propagate better than most surface waves, which is easily shown by clapping your hands together in a large cave or stone building - you can identify the reverberation for many seconds in some cases. Our hearing can detect a vast range of sound energy levels whereas our eyes will not actually see ripples of less than, say 5% of the original amplitude.
     
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