# Pressure block/diagram in hydraulics

1. Sep 23, 2008

### Stacyg

a) Calculate using stress (or pressure) block method, the total force on the side of a tank that is 4m wide and 5.4m deep and contains sea water of specific gravity 1.025.
b) If a 1.20m depth of oil of specific gravity 0.85 was added to the sea water in part a above, draw the new pressure diagram and calculate the pressure at the base of the tank.

I've done part a of the question and have calculated the pressure at the bottom of the tank to be 54.3kpa and the force to be 586.4kN.
But I'm not sure how to do B. Do I calculate the pressure of the oil as it's on top of the sea water and add the two pressures together to get the pressure at the bottom and calculate the force from there?? I have another question similar to this with a layer of oil on top of a layer of seawater, would this be done the same way????

Thanks

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