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Homework Help: Melting of ice

  1. Mar 25, 2005 #1


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    Question #1:
    If all of Earth's polar ice were suddenly to melt into the oceans, in the short term the length of the day would
    a) increase b) remain the same c) decrease d)first decrease, then increase

    The answer is a) , but why?

    Question #2:
    An ice cube of pure fresh water floats on pure fresh water in a glass. A huge ice shelf, also of pure fresh water, floats on the ocean away from Antarctica. Neglecting the contribution due to the density of air, as the ice cube and the iceberg melt,
    a) the water level rises both in the glass and in the ocean
    b) the water level does not change in either case
    c) the water level stays the same in the glass but rises in the ocean
    d) the water level decreases in the glass but stays the same in the ocean

    The answer is c), but why?
  2. jcsd
  3. Mar 25, 2005 #2
    question 1:
    think about conservation of angular momentum
    question 2:
    think about density
  4. Mar 25, 2005 #3


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    Science Advisor


    Last edited: Mar 25, 2005
  5. Apr 4, 2005 #4


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    Thanks xanthym for the good explanation,
    however, I still have a question about the first question.
    If the polar ices are melting, then wouldn't that cause the earth to have a smaller "radius" (from the center of the Earth to the top of the polar ices)? Just like how a figure skater spins faster when her arms are pulled in, wouldn't the Earth spin faster when the ice is gone?
  6. Apr 4, 2005 #5
    Well, if the ice caps melted, you've got a ton more water on the earth than you had initially.

    To relate to your belly dancer analogy, she would pull her arms in, but simultaneously gain a ton of weight.
  7. Apr 6, 2005 #6


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    When a figure skater pulls her arms in while she's spinning, it causes her to spin even faster, right?
  8. Apr 6, 2005 #7
    This is correct
  9. Apr 6, 2005 #8

    Doc Al

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    Staff: Mentor

    When the polar caps melt the water moves away from the axis of rotation. The analogy with the ice skater would be: She starts with her arms overhead, then spreads them wide apart. So her rotation slows down.
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