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Homework Help: HELP!: heating a pot of water on low or high water.

  1. Apr 17, 2007 #1
    HELP!:Real-World Heat Transfer, heating water ....

    Can someone help me with this problem?

    :confused: Suppose you have a carton of milk out of the fridge. It is most energy efficient to:
    a.) immediately return it to the fridge
    b.) leave it out as long as possible

    I am not sure whether this has to do with latent heat of vaporization of latent heat of fusion. Can anyone please help me on this? I'm new to this so i only have introductory knowledge on this topic.:frown:
    Last edited: Apr 17, 2007
  2. jcsd
  3. Apr 17, 2007 #2


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    Gold Member

    It has nothing to do with latent heat. It's about heat capacity and warming and cooling.
  4. Apr 17, 2007 #3


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    :confused: It depends on if you want warm milk. If you want to keep it cold you will put it back in the fridge. If not, don't.

    Now could you please rephrase that, so we have a proplem to solve. Just what are you looking for?
  5. Apr 17, 2007 #4
    we have to find whether it's most energy efficient when we put it in the fridge or leave it as long as possible. i don't really understand the concept
  6. Apr 17, 2007 #5
    simple really, besides the risk of the milk spoiling at room temp, what would require more time to cool to say 40 F, a jug of water that is just below boiling or the same jug at 42 F. Bear in mind it takes energy to cool things, a refrigerator is not a lot different than an air conditioner (but avoid the temptation to open your fridge in the summer to use it as such--do you know why?), so what is the right answer?
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