I am having trouble wrapping my head around the idea of a piston/cylinder type arrangement where the piston has a small area around the outer circumference that would allow air to travel between the front and back of the piston. To clarify, imagine a completely sealed adiabatic cylindrical box with a rigid shaft in the center connecting the ends of the box. On the shaft is a electromagnetic mass "piston", which has a diameter just smaller than the container and is free to move about the axial direction on the shaft. If a force is applied to the mass and it moves in one direction, how are you able to quantify whether or not the air is compressed (in which case the air would act as a non-linear spring) - or if the area between the mass and container diameters would be large enough for the air to escape past the mass and into the are of low pressure on the other side without causing the air-spring effect. Surely, there will be a large gray area where both cases will occur. Again, I am having trouble quantifying how much air would be compressed if any. I have tried using a sealed case where the pressure difference would be found by using P1V1 = P2V2, than introducing Bernoulli''s equation and Continuity to find the flow rate in the opening if it became unsealed at the new state. This doesnt help much though because the pressure P2 used in Bernoulli is in the case of a sealed container and not one where the air is actually escaping past the piston to some degree as it is compressed. Any help is much appreciated, I will try to come up with some diagrams shortly if that would help.