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Homework Help: Some questions for pressure

  1. May 18, 2012 #1
    For Q4.7, why Poil = PHg ?
    For Q4.8, why PH2O = PHg ?
    P is pressure.
    How can I know they are equal from the question?

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  2. jcsd
  3. May 19, 2012 #2
    4.7: hvel=v2/2g the units will be meters of diesel oil. That is not a standard unit to measure head. It is usually measured in meters of water or Hg. To make the conversion convert first to a dynamic pressure, in Pa. Pd=head*specific weight of water (H20. Head in Hg=Pd/specific weight of Hg

    4.8 Total Head=Pressure head+Velocity head+potential head + friction head

    Convert total head in m of water to m of Hg as described above

    Hint: some times you can neglect friction head (friction in piping)
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