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What is water displacement?

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Water displacement is a particular case of fluid displacement, which is simply the principle that any object placed in a fluid causes that fluid to no longer occupy that volume of space. The fluid must go somewhere, however, and so with liquids in containers, this causes their overall height to rise. Gases are also fluids subject to displacement, and they both fill space and are compressible, so an object introduced to a sealed container full of a gas simply decreases the volume of the gas and increases its pressure.

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Fluid displacement in general and water displacement in particular have many important effects. One of these is buoyancy, the reason why objects like corks or boats float in water. When an object displaces water, it is competing with the water for a lower position, since both the object and the water are subject to gravity. If the overall density of the object is greater than water, it sinks. Otherwise, it floats, displacing only as much water as is equivalent to its own weight. Even an object sinking in water undergoes gravitational acceleration as if it weighed only as much as the difference between its own weight and the weight of water it displaces. Combined with the friction from water, this makes many objects sink quite slowly in water.

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Related Questions

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Fluid friction is the resistance to an object's motion through a liquid or gas. When the motion is occurring in a liquid, it is referred to as viscous resistance. Resistance to an object moving through a gas, such as air, is termed air friction.

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There are two formulas that may be used to calculate mass: mass is equal to the volume of an object multiplied by its density (m=v*d) and mass is equivalent to an object's weight divided by the acceleration of gravity (m=w/g). The appropriate formula depends on the available variables.

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Elastic energy is the potential energy stored in a material or physical system as the volume or shape is distorted. When objects are stretched or compressed, elastic energy is stored, according to the Physics Classroom.

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The formula to calculate buoyant force (FB) states that the upward force exerted on an immersed object is equal to the density (ρ ) of the fluid multiplied by both the fluid’s displaced volume (V) and the gravitational acceleration (g), or FB = ρ x V x g. Buoyant forces are the reasons why objects either sink or float in a fluid.