Lift a hemispherical dome filled with water by rotating it

[Bohr1227]

Homework Statement

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.

Homework Equations

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The Attempt at a Solution

Shown in the attached picture.

 

[Nidum]

I don't understand this problem . Angular velocity of what ? How does whatever it is act on the hemisphere to lift it ??

 

[Bohr1227]

I don't understand this problem . Angular velocity of what ? How does whatever it is act on the hemisphere to lift it ??

I'm sorry, I have tried to make the problem clearer now :)

 

[CWatters]

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

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