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Homework Help: Velocity of efflux.

  1. May 6, 2017 #1
    1. The problem statement, all variables and given/known data

    The velocity of efflux of a liquid through an orifice in the bottom of the tank does not depend upon:

    A. Size of orifice

    B. Height of the liquid
    C. Acceleration due to gravity
    D. Density of the liquid

    2. Relevant equations

    3. The attempt at a solution
    My textbook says that Vefflux=√2gH.
    The answer given is size of orifice.
    How is it dependent on density? Also, if I take a very very small orifice and then a very large orifice, will the velocity be same?
    Does density vary for large H?
  2. jcsd
  3. May 6, 2017 #2


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    Science Advisor
    Homework Helper
    Gold Member

    There is no claim that the speed of efflux is dependent upon the density. Read the question. It asks to pick the variable on which the speed does not depend.
    Yes, but the time it will take for the tank to empty will not.
    If the fluid is incompressible, no.
    I suggest that you write down Bernoulli's equation at the free surface of the fluid and at the exit point of the fluid and see what you get.
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