Hows buoyant force is related to density?

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Hows buoyant force is related to density?

Postby nissan » Sun Feb 19, 2012 8:48 am

An object floats or sinks based on density. If the object is less dense of the fluid it is submerged in, it will float. But how is buoyancy coming into picture.. I read many links but still not getting the concept.Any help please?
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Re: Hows buoyant force is related to density?

Postby rmarz » Sun Feb 19, 2012 9:21 am

nissan - Maybe some definitions will help. Density is defined as mass (or weight) per unit of volume (cubic centimeters, cubic inches, liters, etc). Therefore Density=Mass/Volume. Density of objects is often compared in terms of the two fluids we see most often in our lives every day: Air and water. Bouyancy is the pressure acting on an object by the fluid it is contained by. For example, it an object has a density greater than the fluid it is surrounded by, it will sink to the bottom of the container. If the object has a density less than the fluid it will float in the fluid. It will not float directly on the top surface, but at some level where the fluid displaced by the objects submerged volume equals the mass (weight) of the fluid it displaces. It is in equilibrium. That is why a simple model of a boat hull will float at a certain level in the liquid. Research 'hydrometer' and see how an instrument can be constructed that actually measures the density of a fluid. Do a search on "Archimedes principal" for more information.

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Re: Hows buoyant force is related to density?

Postby rmarz » Sun Feb 19, 2012 9:29 am

Slight correction

nissan - Maybe some definitions will help. Density is defined as mass (or weight) per unit of volume (cubic centimeters, cubic inches, liters, etc). Therefore Density=Mass/Volume. Density of objects is often compared in terms of the two fluids we see most often in our lives every day: Air and water. Bouyancy is the pressure acting on an object by the fluid it is contained by. For example, it an object has a density greater than the fluid it is surrounded by, it will sink to the bottom of the container. If the object has a density less than the fluid it will float in the fluid. It will not float directly on the top surface, but at some level where the fluid displaced by the objects submerged volume equals the mass (weight) of the object in the fluid.. It is in equilibrium. That is why a simple model of a boat hull will float at a certain level in the liquid. Research 'hydrometer' and see how an instrument can be constructed that actually measures the density of a fluid. Do a search on "Archimedes principal" for more information.
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