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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.
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).
In other words, for an object floating on a liquid surface (like a boat) or floating submerged in a fluid (like a submarine in water or dirigible in air) the weight of the displaced liquid equals the weight of the object. Thus, only in the special case of floating does the buoyant force acting on an object equal the objects weight.
A Cartesian diver or Cartesian devil is a classic science experiment which demonstrates the principle of buoyancy (Archimedes' principle) and the ideal gas law.The first written description of this device is provided by Raffaello Magiotti, in his book Renitenza certissima dell'acqua alla compressione (Very firm resistance of water to compression) published in 1648.
If the weight of the object is less than this displaced quantity, the object floats; if more, it sinks. The amount of fluid displaced is directly related (via Archimedes' principle) to its volume. In the case of an object that sinks (is totally submerged), the volume of the object is displaced.
Jan. 23—Q: We're always wondering, why does wood burn in squares? You sit around any kind of a wood fire, you notice the wood always burns in squares. We're always wondering why.
Lignum vitae is hard and durable, and is also the densest wood traded (average dried density: ~79 lb/ft 3 or ~1,260 kg/m 3); [4] it will easily sink in water. On the Janka scale of hardness, which measures hardness of woods, lignum vitae ranks highest of the trade woods, with a Janka hardness of 4,390 lbf (compared with Olneya at 3,260 lbf, [5] African blackwood at 2,940 lbf, hickory at 1,820 ...
How your stool behaves in the toilet can say a lot about your health.