What is the reason for the pushing out of the body by the liquid (gas)?

A buoyant force acts on any body immersed in a liquid or gas (its other name is Archimedean force, in honor of the ancient Greek scientist Archimedes who discovered it). It is equal to:

Aarchimedes = ROjid * Vbody * g, where:

RO liquid = density of the liquid (or gas) in which the body is immersed (kg / m ^ 3);

Vbody – the volume of a body immersed in a liquid or gas (m ^ 3);

g – acceleration of gravity, equal to 9.8 m / s ^ 2;

Aarchimedes – buoyant (Archimedean) force, Newton.

This force is always directed upward, against the action of gravity, therefore, if the density of the liquid is greater than the density of the body, then the body immersed in the liquid or gas will move upward.