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Homework Help: Simple simple question

  1. Mar 25, 2006 #1
    Hi guys,

    I'm doing a physics science fair, and I was just wondering if you guys know any cooling laws related speifically to surface area.

    You see, for my science fair, I got three jars that had the same volume, but different surface areas. Then I filled them with hot water to see which one could come to room temperature fastest.

    I need a law that I was supposedly "verifying" for my experiment.
    I'd really appreciate any information.

    Thanks!
     
  2. jcsd
  3. Mar 25, 2006 #2

    chroot

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    You're looking for Newton's law of cooling:

    http://en.wikipedia.org/wiki/Newton's_law_of_cooling

    Heat conduction (energy per unit time) is linearly proportional to the surface area.

    - Warren
     
  4. Mar 25, 2006 #3
    hmm.. I don't kno.. isn't Newton's law about the difference in temperatures between the two things? I need something that deals with surface area and heat loss.

    Am I right, or am I just confused?
     
  5. Mar 25, 2006 #4

    chroot

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    Look at the equation. A is the area. As I said, the heat conduction varies linearly with the area.

    - Warren
     
  6. Mar 25, 2006 #5

    Integral

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    You are correct in that Newton's law deals with a difference in temperature. It gives the energy transfer between objects of different temperature, but there is more to it then just temperature.

    The temperature of a match is about the same as that of a bonfire (both are burning wood) but the difference in the amount of heat transferred by the 2 sources is huge. Newton's law assumes that the key factor in the difference is the surface area of the 2 sources.
     
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