Fluid Mechanics Problem: Water Forces on a Parabolic Gate

[ktjj4]

Homework Statement

Hello, I'm a little confused for this part of the fluid mechanics problem. I got through calculating the forces of the water on the gate but then it asked me to calculate the horizontal and vertical forces at a certain point (A) on the curved gate to keep equilibrium. I know I have to take the moment about the origin (O) but I am unsure as to why I only have to consider one of the component forces (F_Ax) but not the other (F_Ay). I'm not sure if this is a conceptual thing or if my knowledge of moments is missing something.

Relevant Equations

Sum of M = -Fv(x') + Fh(D-y') - F_Ax(H)

 

[NascentOxygen]

I am unsure as to why I only have to consider one of the component forces (F_Ax) but not the other (F_Ay).

The application of an external force at A can keep the gate closed. This force could be directed (i) horizontally, or (ii) purely vertically, or (iii) at an angle. The exercise you are dealing with involves case (i), and case (ii).

 

[ktjj4]

The application of an external force at A can keep the gate closed. This force could be directed (i) horizontally, or (ii) purely vertically, or (iii) at an angle. The exercise you are dealing with involves case (i), and case (ii).

I see, thank you for clarifying that. I assumed the question was asking me to find the components of a force at an angle. Thank You again!