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Warm air coming from our lungs

  1. Mar 21, 2005 #1
    Consider a hot potatoe. Will it cool faster or slower when we blow the warm air coming from our lungs or if we let it cool naturally in the cooler air room?
    How do i explain this in physics terms?
  2. jcsd
  3. Mar 21, 2005 #2

    Chi Meson

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    Who are you, Dan Quayle? :tongue2: Ha! I got it first!

    Seriously. IF you just leave the potato to cool in still air, the potato will first warm the air that surrounds it to a couple of hundred degrees F.

    Convection will cause this air to rise and thus will pull cooler air from the sides, but a breeze from your lungs will replace this air with cooler air faster than convection will.

    Furthermore, if you blow with high pressure through a very narrow opening, the sudden expansion of you breath (going from high to low pressure) will cause it to cool to below room temperature.

    Try this: blow on your fingers with the intention of cooling them. (By blowing through narrow opening in lips)

    Now blow on your fingers with the intention of warming them up. (with your mouth wide open). Note the huge difference in temperature of you own breath.
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