# Homework Help: Proving A Hydraulics Equation

1. Sep 23, 2008

### Stacyg

Prove that the resultant force F on a plane surface of area A immersed vertically in a liquid of density (rho) is given by the equation:
F=rho.g.A.z
Where 'z' is the depth to the centroid of the plane area below the liquid surface level.

I under stand how F is found using this equation and how the force changes depending on the z value. But I don't know how to put this answer in a suitable way for my assignment.

Thanks

2. Sep 23, 2008

### dirk_mec1

The pressure is given by $$p= \rho g \Delta h$$. The force F is given by $$F = pA$$. It's that easy!