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Homework Help: Challenging question on fluid dynamics

  1. Mar 7, 2012 #1
    1. The problem statement, all variables and given/known data

    A 150 m^3 silo(cylinder) (12 m high) is used to store cream (density 850 kg m-3). An electronic pressure sensor (measures gauge pressure) is mounted 0.6 m up from the base of the tank, and a 0 to 100% display is used to indicate the level. It is not possible to sense
    the level once it is below the sensor, but the display can be calibrated with a constant
    offset to account for this extra fluid (for example, the sensor can show 10% when
    there is no pressure). Derive an equation to relate the display reading (in %) to the
    sensor pressure. What offset should be used on the display to account for the 0.6 m
    mounting height? If water is used instead of cream, how high must the silo be in
    order for the display (calibrated for cream) to read 100% when the silo is full?

    2. Relevant equations

    P=F/A
    P=ρ+ρgh
    ρ=m/v
    Q=Av

    3. The attempt at a solution
    I have no idea where to start where can I start with ok

    m=ρV=850/150=5.7kg

    I am not sure how to derive an equation to relate the display reading (in %) to the
    sensor pressure.

    Any clues guys

    cheers
     
  2. jcsd
  3. Mar 7, 2012 #2
    would I be able to use Bernoullies principle on this question?
     
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