# Tagged Questions

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### What does the absence of hydrodynamic entrance effects do to the momentum conservation Equation?

I am trying to do a homework problem where we re-write the mass, momentum and energy conservation formulas for downward flow in a vertical pipe and it says "where all hydrodynamic entrance effects ...
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### What kind of energy does superfluidity use?

Liquid helium (and other similar fluids) can "climb up" the walls of their containers. Who does the work in this case, and what kind of energy does it use? I'm sure we can't make a perpetuum mobile ...
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### When moving something by entrainment in a fluid stream, where does the energy come from?

The particular Something I had in mind here would be air bubbles that are pulled downwards against their buoyancy by a stream of water falling down a shaft. The work required to push those bubbles ...
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### Finding an equation relating the mass of a blade of a wind turbine to its velocity

I'm writing up my physics coursework and I thought I'd try and find an equation described in the title. This is my attempt: Is it correct?
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### Conservation of energy in objects at terminal velocities

In vacuum, object free falling under gravity, the sum of Gravitational Potential Energy(GPE) and Kinetic Energy (KE) is a constant. The GPE is a decreasing side of a quadratic and KE is a increasing ...