# Homework Help: Fluid question

1. Feb 14, 2010

### rabbit44

1. The problem statement, all variables and given/known data
Estimate how much higher the water level is on the French coast than on the English coast when there is an eastward flow through the English Channel at a typical speed of 1m/s. You may assume that the English Channel is approximately 30km wide.

2. Relevant equations
An earlier part of this question got me to derive the equation for when there is geostrophic balance:

$$2\Omega \times \textbf{u}_{R} = -\frac{1}{\rho} \nabla p$$

3. The attempt at a solution
I think I probably have to use the above equation, or the Rossby number, as I am given enough parameters to calculate it. I can calculate the left hand side of the above equation as I am given the magnitude and direction of the flow everywhere, and I can calculate the angular rate of rotation of the Earth from its 24 hour period. I can look up the density of sea water I guess. But then I don't know how to use grad(p) to give me a difference in sea level. I thought maybe something to do with hydrostatic equilibirum, but basically I'm really confused.

Any help would be very much appreciated!