1. The problem statement, all variables and given/known data [PLAIN]http://img266.imageshack.us/img266/447/814h.jpg [Broken] 2. Relevant equations 3. The attempt at a solution In the solution, they integrate the pressure gradient over the width and equal it to the force. This gives a relation between the initial pressure, the force and the width W. F = b∫P(x)dx = Pi * bW/2 where b is the width perpendicular to the diagram. This part I understand, but I don't know how they found the pressure distribution to be: P(x) = Pi (1 - 2x/W) I though about using Navier-Stokes but this would involve viscosity. Can someone point me in the right direction as to how I should find the pressure distribution in this problem? Thank you very much.