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Water Bucket Momentum Question

  1. Jul 8, 2010 #1
    1. The problem statement, all variables and given/known data

    A bucket full of water is slid across a sheet of ice in the rain. As the bucket fills, what happens to its velocity and its momentum? ( assume no friction)

    2. Relevant equations


    3. The attempt at a solutionI reasoned that since the bucket gained mass it gained momentum and that since no force acted on the bucket in the horizontal direction v stayed constant.

    Answer given: velocity decreases and momentum remains constant
    Does this means momentum is a conserved quantity?
  2. jcsd
  3. Jul 8, 2010 #2
    What would happen if instead, the bucket was moving along at a constant velocity and without interfering with the bucket or the ice, you were able to suck water out of the bucket?
  4. Jul 8, 2010 #3


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    Homework Helper

    Yes momentum is a conserved quantity.

    If initially it has momentum p=m1v1

    and after it has p=m2v2

    Then m2v2=m1v1 or v2 = (m1/m2)v1

    So if m2 increases then v2 will decrease.
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