Upthrust

Pressure acting over a surface produces a force, making the upward force on the bottom greater than the downward force on the top. Their resultant is an upward force called upthrust.

Opposing sideways forces balance, but the vertical forces do not. Their resultant is an upward force called upthrust.

Water pushes upwards on it with a force called upthrust. Archimedes’ principle states that this upthrust equals the weight of the water displaced.

The pressure on the lower surface is greater than the pressure at a higher surface, so the fluid’s forces have an upward result. This upward force is upthrust. The same principle applies to a fully submerged object and, more generally, to objects in gases.