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Heat transfer & sound transfer

  1. Apr 10, 2008 #1
    If I stand at the corner of a largely room with a room-temperature and burn something with flames for few seconds, it'll hardly change the temperature of the other corner far away.
    Yet, If I whistled event softly it could be clearly heard at any point in the room -instantly-.

    Each phenomena occurs due to the disturbance of air molecules and the kinetic energy is carried away (by waves??). So how come the effect of the later is much sharper?
    Is it because humans are more sensitive to sound-change(volume) than thermal change?
  2. jcsd
  3. Nov 10, 2015 #2
    -thermal energy would travel to the other side of the room through convection currents in the air mainly in the example given
    -the sound would travel 'directly' to the other side of the room although dispersed radially in the air
    -if your room was filled with solid the heat transfer would rely on the conduction of the heat and the heat would travel in a similar way to the sound I think
    -it could also have something to do with the relative energies? Heating something for a few moments in any reasonable sized room wouldn't prove a noticeable difference in energy to heat the other side of room (especially in the bottom corner as heat rises) whereas in a small cupboard you would definitely feel the heat on the other side if someone had a lighter out for a period of time.
    - Also heat is probably absorbed better by the surrounding walls whereas more sound energy will be reflected to the observers ears
    - and your probably right, we are probably more sensitive to sound than heat (but then again what does that mean 'more sensitive'? Relative to what on what scale haha)
    -also you said the sound can be heard instantly, your were probably just exaggerating on purpose for effect, I'm sure you know that it's not instantly just the speed of sound in air which over small distances is very quick, but not instant
    Just my thoughts, I'm only an a level student so it's probably all wrong
  4. Nov 10, 2015 #3
    Even in a solid, and even if you induce a "thermal wave", this is critically damped and will die over a distance given by the diffusion length.
    Whereas sound propagates through waves, the heat is transferred by diffusion which is much slower. Unless there is some convection which will speed up the transfer but still way below the speed of sound. .
  5. Nov 10, 2015 #4
    Yes. As nasu indicates, the fundamental physical mechanism for heat transfer is completely different from the physical mechanism for sound propagation. Sound is the result of compression waves in the air that propagate spatially very rapidly. Heat is transferred by convection and conduction, which are much slower transport processes.
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