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Ice Cube

  1. Nov 21, 2003 #1
    stuck in explaining this problem

    A glass of water contains a large ice cube

    the glass can hold no morw water

    the ice is floating in the water

    what will happen to the water level when the ice melts?
  2. jcsd
  3. Nov 21, 2003 #2
    Last edited: Nov 21, 2003
  4. Nov 21, 2003 #3


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    I disagree. The ice cube is made wholly of water in a cryistaline form and therefore its mass although lower than liquid water would still diplace the same amount of water as is contained within the cube. if the cube melts the water from it will replace exactly the water that was originally displaced by the cube. therefore the level will remain the same.
  5. Nov 21, 2003 #4


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    Rog has it right. A floating object displaces its mass, a sunken one displaces its volume. Remember Archimedes.

  6. Nov 21, 2003 #5
    Is a perfect ice cube is made of wholly crystaline water? Aside from bubbles or such trapped particles, (which I am discounting), does the surface of the cube remain as a solid, or is it in a dynamic process of changing it's state?
  7. Nov 21, 2003 #6
    It doesn't matter. Even if the ice cube was an ice bubble, the amount of water it displaces is identical [to the volume (melted) of the water contained in the ice].
  8. Nov 21, 2003 #7
    I know the answer to this question! I did this question for my hw.

    The answer is the water level will lower and then rise. I'm not sure at what temp, but water has a different density at certain temp. I think near 3 or 4 C, the density is lower than at other temp.
  9. Nov 24, 2003 #8


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    H20 does some strange things around its melting point, there is not realy enough information in the problem to allow for those small effects. You would need to know the starting temperature of the water, and the ice, and their masses etc. If the thermal expansion coefficient of liquid water were monotonic, you could do what you say, but water is at it's maximum density at 4 degrees C I believe. Heat it or cool it from that point and it expands.

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