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Latent heat comparing ice to wood

  1. Jun 15, 2009 #1
    You bought two kilograms of ice at -10 degrees celcius for your cooler when a friend suggests to instead use two kilograms of wood at -10 degrees celsius. Why should you stick with your ice?
    Thermal Conductivities Latent Heats Specific Heats
    Answer with either Good Reason, True but Irrelevant, Wrong

    1.The latent heat of the ice is going to keep your drinks cooler for longer.

    2.Water has a higher specific heat.

    3.The heat conductivity of water is higher than the heat conductivity of wood.

    4.Wood has a higher specific heat.

    5.The heat conductivity of wood is higher than the heat conductivity of water.
    I answered
    1. Good Reason- I thought that the latent heat of ice would keep the cooler colder for longer. I also answered this same set of answers but this one marked as Wrong- but now I have changed it correct.
    2. True, but irrelevant- Water does have a higher specific heat than wood so its true but it should be irrelevant because we are talking about ice and wood.
    3. Good Reason- This is true I think so my only two options are good, which I answered but is this irrelevant?
    4. Wrong- This is not true.
    5. Wrong- This is not true.


    Any help on where I am going wrong on this question?
    Thanks,
     
  2. jcsd
  3. Jun 15, 2009 #2

    LowlyPion

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    Homework Helper

    You have three numbers to consider with the ice. The specific heat of ice, the heat of fusion ice to water, and specific heat of water. If both the specific heats of water or ice are more than wood, then for any temperature, even above freezing, you will have delivered more cooling to the drinks. Without knowing what wood is relative to both, it may be more challenging to answer.

    Roughly speaking ice specific heat is half that of water, and the heat of fusion is 160 more than that needed for a 1 degrees change in ice.
     
  4. Jun 15, 2009 #3
    I assume you're not a fisherman. Why do you have water in the cooler?
     
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