Translation and increase a volume

neufneufneuf

Blue part is a liquid helium under pressure, it's a theoretical study. I move down blue part and in the same time I increase volume of cone (theoretical walls). The system is always in the same configuration, but it move. No gravity here. When I increase volume of cone I must need the energy I recover from blue part but the curved shape of atoms reduce the pressure on surface, true ?

neufneufneuf

A little mistake on drawing, look at top view please.

I added 3 positions in space of object at different times.

neufneufneuf

When the cone (not really a full cone) is increasing its diameter, the curved shaped must be changed in the same time (not same diamaters) but the energy needed is not more than due to "maintain" the pressure of curved shape. The curved shape is moving and deform itself in the same time.

Drawing: shows blue part moving if curved part don't move for understand the movement.

neufneufneuf

The curved shape give forces to atoms in the curve. This force is noted F. It's composed of Fp+Fr (in vector). Fp is full compensated by the blue shape because at end of each curve (for each layer of atoms) there is a surface of blue shape. Fr is compensated by blue shape too (end of layers) but when blue shape is moving down this force don't work because it is perpendiculary to the movement. When curved surface move to the left, it need less work for maintain atoms in place I think. Or Fr don't exist ?

image d6: forces Fp/Fr

image d7: shape easier to study I think

Maybe study one layer of atom (or balls) is easier.

neufneufneuf

I understood, it's because the lack of force is only at left and don't work too.