Submerge the plastic ball in water. Why does it pop up?

All bodies immersed in a liquid are acted upon by the force of Archimedes, striving to push the body out of the liquid. If the force of Archimedes is greater than the force of gravity acting on the body, it floats, if on the contrary, it sinks, and if these forces are equal, then it moves freely throughout the volume of the liquid. If the body is solid, like a plastic ball, it will float if the density of the substance it consists of is less than the density of the liquid. The density of plastic is less than that of water, so the ball floats up.