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Homework Help: Pressure in a closed system using an inclined manometer

  1. Apr 12, 2013 #1
    1. The problem statement, all variables and given/known data
    In the figure attached the pressure at A and B are the same 100 kPa. If water is introduced at A to increase p_A to 130 kPa find the new positions of the mercury menisci. The connecting tube has a diameter of 10 mm. Assume no change in Liquid density.

    2. Relevant equations

    P A - P B = ρmerc g (Δ L) sin σ

    3. The attempt at a solution

    30 000 = (13600)(9.81) (Δ L) (0.26)
    ΔL = 0.868
    h = 0.225 m

    Intuitively this answer should be wrong because if there is an increase in pressure at A it should transfer through out the system to create an equilibrium. There would be no change in the mercury menisci if the air did not compress.

    I think I need to work out a change in air density to get the correct answer. I am also not sure why they mentioned the diameter of the connecting tube.

    Would you mind helping me get on the correct track.

    Thank you

    Attached Files:

  2. jcsd
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