# Challenging question on fluid dynamics

1. Mar 7, 2012

### joe98

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. Mar 7, 2012

### joe98

would I be able to use Bernoullies principle on this question?