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Homework Help: Fluid Manometer Question

  1. Apr 29, 2013 #1
    1. The problem statement, all variables and given/known data

    The manometer illustrated in Fig. Q2 contains water and kerosene (specific
    gravity of 0.82) as indicated. With both ends of the U-tube open the height
    H0 =20 mm.
    (i) Determine the height, h , when both ends of the tube are open. [4]
    (ii) Determine the new value of H0 when a gauge pressure of 98 Pa is
    applied to the right end of the U-tube. [6]

    2. The attempt at a solution

    I can do part (a), getting an answer of 91.1mm.

    However, I am stuck on part (b).. I assume I cannot keep h constant and see the variation in Ho with the added pressure?

    I am unsure how to work out the two unknowns h and Ho with only the one equation.

    Attached Files:

  2. jcsd
  3. Apr 29, 2013 #2
    In part (i), you determined h, so, from the figure, you now know that total length of the kerosene column. This doesn't change in part (ii).
  4. Apr 30, 2013 #3
    Are you sure h doesn't change? In my lecturers solutions it does change.. I don't really understand his solutions but maybe you can explain?

    I have attached his solution.

    Attached Files:

  5. Apr 30, 2013 #4
    I didn't say h doesn't change. I said that the total length of the kerosene column doesn't change.

  6. Apr 30, 2013 #5
    Oh I see, sorry I didn't read that carefully enough. Thank you I get it now! :)
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