Question

What is the meaning of the "-" signs in this equation of the vertical pressure variation in a static fluid?

-(∂P/∂z)-ρ*g=0

I'm not sure, but I think the signs "-" are there because the force due to the pressure increases with the depth in order to compensate the weight of the fluid. Could someone clarify and explain clearly this, please?

Answer 1

it's for nothing
it's the same as: +(∂P/∂z)+ρ*g=0
but in other cases you may take the direction of the force and pressure into account, like you may have this form: +(∂P/∂z)-ρ*g=0