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Homework Help: Lift a hemispherical dome filled with water by rotating it

  1. Feb 12, 2017 #1
    1. The problem statement, all variables and given/known data
    A hemispherical dome filled with water, radius 2 m and weight 30 tons, can be lifted by giving it a constant angular velocity around its vertical line of symmetry. The dome has a hole on the top. Decide the minimum angular velocity.

    My answer is 2.91 rad/s .
    The correct answer is 1.95 rad/s.

    2. Relevant equations
    Shown in the attached picture.

    3. The attempt at a solution
    Shown in the attached picture. phys.png
    Last edited: Feb 12, 2017
  2. jcsd
  3. Feb 12, 2017 #2


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    I don't understand this problem . Angular velocity of what ? How does whatever it is act on the hemisphere to lift it ??
  4. Feb 12, 2017 #3
    I'm sorry, I have tried to make the problem clearer now :)
  5. Feb 14, 2017 #4


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    How does rotating something cause translation? Sounds like a breach of conservation of momentum?

    Edit: So the water isn't lifted, just the hemisphere?
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