Buoyancy

Upward force that opposes the weight of an object immersed in fluid The forces at work in buoyancy. The object floats at rest because the upward force of buoyancy is equal to the downward force of gravity. Buoyancy (/ˈbɔɪənsi, ˈbuːjənsi/), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may also be a parcel of fluid). The pressure of a fluid increases with depth below the fluid's surface because of the weight of the fluid above. Thus, the pressure at the bottom of a container of fluid is greater than at the top of the container. Similarly, the pressure at the bottom of an object submerged in a fluid is greater than at the top of the object. This pressure difference results in a net upward force on the object. The magnitude of the force is proportional to the pressure difference, and, as explained by Archimedes' principle, is equivalent to the weight of the fluid that would otherwise occupy the submerged volume of the object, i.e. the displaced fluid. An object under the influence of gravity with an average density greater than the surrounding fluid tends to sink because its weight is greater than the weight of t