Sum of force on an curved solid in liquid

neufneufneuf

A solid is placed in a liquid (helium or hydrogen for example). Gravity is perpendicular to the screen. I would like to understand how sum of forces on solid can be at zero. The curvature of the solid force atoms to shaped like it. In the curve part, atoms press solid but like atoms press each others (black force) a red force appears on each atom where there is the curvature. So it's like object has a sum of force in one direction. And atoms move to the same direction in the same time. What force compensate this ?










Another shape for solid. It's possible to add a lot of solid around the torus. Solid and atoms have force in the same direction.






Maybe it's temperature or another atomic effect that compensate the force but with macroscopic compressible balls or magnets I don't understand how sum of forces can be to zero on solid and in balls too. Even balls need energy to compress it when the system move, this energy is recover if friction is very small.

dlouth15

Maybe extend your analysis to include not only those balls in contact with the solid but also the rest of the balls making up the liquid. You may find that the balls on the convex surface have additional forces due to these other balls than the balls making contact with the concave surface, and that these compensate for the outward force.

neufneufneuf

Imagine you have a recipient full of liquid, on Earth. It's a theoretical study. Gravity is perpendicular to the screen. One surface is curved and can move, the surface can increase its length (theoretical study). You're moving this curved surface, the liquid move down because the surface increase. You win energy needed for move up the liquid (before), sum is zero. But red forces give energy, no ?

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