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It can be the case that forces other than just buoyancy and gravity come into play. This is the case if the object is restrained or if the object sinks to the solid floor. An object which tends to float requires a tension restraint force T in order to remain fully submerged.
The effect is observed in small objects which are supported by the surface of a liquid. There are two types of such objects: objects which are sufficiently buoyant that they will always float on the surface (for example, Cheerios in milk), and objects which are heavy enough to sink when immersed, but not so heavy as to overcome the surface tension of the liquid (for example, steel pins on water).
While this basic idea carried enormous weight and has come to form the basis of understanding why objects float, it is best applied for objects with a characteristic length scale greater than the capillary length. What Archimedes had failed to predict was the influence of surface tension and its impact at small length scales.
Buoyancy (/ ˈ b ɔɪ ən s i, ˈ b uː j ən s i /), [1] [2] or upthrust is a net upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid.
Leidenfrost droplet Demonstration of the Leidenfrost effect Leidenfrost effect of a single drop of water. The Leidenfrost effect is a physical phenomenon in which a liquid, close to a solid surface of another body that is significantly hotter than the liquid's boiling point, produces an insulating vapor layer that keeps the liquid from boiling rapidly.
Neutral buoyancy occurs when an object's average density is equal to the density of the fluid in which it is immersed, resulting in the buoyant force balancing the force of gravity that would otherwise cause the object to sink (if the body's density is greater than the density of the fluid in which it is immersed) or rise (if it is less).
Several methods of such measuring exist. In one case the increase of liquid level is registered as the object is immersed in the liquid (usually water). In the second case, the object is immersed into a vessel full of liquid (called an overflow can), causing it to overflow. Then the spilled liquid is collected and its volume measured.
A levitation illusion is one in which a magician appears to defy gravity by making an object or person float in the air. The subject may appear to levitate unassisted, or it may be performed with the aid of another object (such as a silver ball floating around a cloth) in which case it is termed a "suspension".