I need to balance forces on the "plate" of a piston situated in a closed container of a given spring constant k and area A with a compression x. It is also given that the initial pressure inside the container is P°
Thus PA = kx
Now here is my question, would P be the value of the net final pressure inside the container or would it be the change in pressure relative to initial pressure ? I think it should be the former but i've been told otherwise and can't wrap my brain around as to why is it so.