So, I'm having trouble answering an assignment. I need to find the force in the spring just before the gate opens, and I know how to get exactly that (taking the moment at A). But, I'm having trouble finding Fv.
In my understanding, Fv is the weight of the fluid above the curved surface, at least that's what my textbook says so. But, in this problem, the fluid above the arc is different from the one below it. What then would be the hydrostatic force Fv of the water if the fluid above the curved surface is not water? Will there be two Fv? One from the hydrostatic force exerted by the water (upward) and one from the hydrostatic force exerted by liquid X (downward)? How do I find it?
I'm really having a hard time trying to imagine what the FBD looks like, so any help will be appreciated.