1. The problem statement, all variables and given/known data Find the horizontal force across the partition in a water tank with two compartments, one filled with water to x height and the other with water to y height. I've worked out the thrust acting on the partition as a result of density, height, gravity and average depth, so I have two horizontal vectors, with which to find the total horizontal force. 2. Relevant equations F=PaA P=pgh F=pgha 3. The attempt at a solution (sum) Fx=(Force from oil) - (Force from water). Problem is I don't know which force is in which direction relative to the partition. The only solution I can see, which would make sense is adding the two forces together. Is this correct?