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Physics in Honey I Shrunk the Kids

  1. Jan 30, 2010 #1
    When you shrink down humans isometrically to a 1/4 of an inch, what happens to how their voices are perceived by regular size humans?

    Also, would the shrunk humans have different hearing abilities at this small scale?
  2. jcsd
  3. Jan 30, 2010 #2


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    There's a more fundamental problem. If you shrink someone, do their atoms shrink?

    If they do, how would say oxygen be taken up by your lungs and bond to your hemoglobins.

    If the atoms don't shrink, how could you expect the same structure to result?
  4. Jan 30, 2010 #3
    I'd bet that the regular size humans wouldnt hear them very well.
    About the hearing ability though, Im not too sure. The hearing sensitivity shouldnt change though.
  5. Jan 30, 2010 #4

    You just p0wned the movie..

  6. Jan 30, 2010 #5
    I think the frequency of the voice will increase significantly, since the wavelength of the voice will probably decrease proportionally with the body length. So, assuming initial height 180cm, final height 1cm, as well as a bass note at 80Hz. The "same" note as sung by the miniature guy will have a frequency around 14kHz. I.e. almost inaudible. Not to talk about the amplitude, which would be much smaller.

    Their ears would be affected similarly. They wouldn't be able to hear the bass notes that we can hear. If our lower threshold is 20Hz, theirs would be 3600Hz, which is already quite trebly (almost the highest note on the grand piano).

    I must mention I have heard about little people that can sing quite a deep bass, although he might have had the same size vocal cords and that would explain it.

  7. Mar 9, 2010 #6
    So, we'll say the kids were shrunk by a factor of 200. What about vision affects? For example, at a distance of 1.0 m from a child, how far apart would 2 point sources of light have to be, to be resolvable (this is the sharpness of the kids vision)? Wouldn't the resolution be too low for the kids to have good vision? Probably, but how do insects overcome this same issue?

    Speaking of insects and size, why are there no mammals this small in stature (1 cm high)? And then back to the childeren in the above film, wouldn't they have trouble staying warm?
    Last edited: Mar 9, 2010
  8. Mar 10, 2010 #7

  9. Mar 11, 2010 #8
    Interesting question and speculation. I once asked the opposite question to a physicist I worked for. I speculated if overnight everything got 10 times larger could you tell? His answer was yes, you could. The clue he asserted would be that all the sausages would fall down at the meat market. You see the weight of the sausages is determined by the VOLUME of the sausage. While the strength of the string holding them up is determined by the diameter of the string. (cross-sectional area) Since one goes by the square and the other by the cube the new weight of the sausages would be too much for the strings to hold up!

  10. Mar 11, 2010 #9
    Yes, this is the reason why an ant can lift objects many times its own weight, while I cannot do this even though the diameter of my legs relative to the length of my body is larger than for an ant.

    King King should need to have very different proportions to make him more realistic :smile:

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