What is the principle of buoyancy?

The principle of buoyancy refers to the upward force that a fluid exerts on an object that is submerged or partially submerged in it. This force acts against the weight of the object and is what allows objects to float or rise in the fluid. The concept is rooted in Archimedes' principle, which states that the buoyant force is equal to the weight of the fluid displaced by the object.

In this context, the upward force acting on a submerged object is what keeps it from sinking, and it is this principle that is fundamental in understanding how vessels maintain stability and floatation in water. When the weight of the fluid displaced by the submerged object equals the weight of the object itself, the object achieves buoyancy.

Other options, such as the downward force of a fluid or the weight of the fluid displaced, describe related concepts but do not accurately define buoyancy as the upward force exerted by the fluid. The force acting on the surface of a liquid pertains more to pressure than to buoyancy itself.