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Submerged specific gravity is a dimensionless measure of an object's buoyancy when immersed in a fluid.It can be expressed in terms of the equation = where stands for "submerged specific gravity", is the density of the object, and is the density of the fluid.
An object whose weight exceeds its buoyancy tends to sink. Calculation of the upwards force on a submerged object during its accelerating period cannot be done by the Archimedes principle alone; it is necessary to consider dynamics of an object involving buoyancy. Once it fully sinks to the floor of the fluid or rises to the surface and settles ...
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
Measurement of volume by displacement, (a) before and (b) after an object has been submerged; the amount by which the liquid rises in the cylinder (∆V) is equal to the volume of the object. The most widely known anecdote about Archimedes tells of how he invented a method for determining the volume of an object with an irregular shape.
The fluid pressure behind the object is lowered below the vapour pressure of the liquid, forming a bubble of vapour (a cavity) that encompasses the object and reduces drag. Supercavitation is the use of a cavitation bubble to reduce skin friction drag on a submerged object and enable high speeds.
It is also used to image water column density, when locating submerged objects, or determining water depth . Physical scientists use gravimeters to determine the exact size and shape of the earth and they contribute to the gravity compensations applied to inertial navigation systems.
is the drag coefficient – a dimensionless coefficient related to the object's geometry and taking into account both skin friction and form drag. If the fluid is a liquid, c d {\displaystyle c_{\rm {d}}} depends on the Reynolds number ; if the fluid is a gas, c d {\displaystyle c_{\rm {d}}} depends on both the Reynolds number and the Mach number .
The lift coefficient is a complex factor which depends amongst other things on the ratio rω/v, the Reynolds number, and surface roughness. [12] In certain conditions, the lift coefficient can even be negative, changing the direction of the Magnus force (reverse Magnus effect). [4] [13] [14]