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-   -   Does the buoyant force change in different fluids? (http://www.physicsforums.com/showthread.php?t=587479)

jayadds Mar16-12 02:00 AM

Does the buoyant force change in different fluids?
 
Given two objects of identical density and weight, one is floating on water and the other is floating on saltwater. Is the magnitude of buoyant force acting on the object the same in the two situations? From my thinking, it seems that the weight of the object in the the two situations should not change and so the buoyant force should not change as well (Archimedes principle). Correct me if I'm wrong in that thinking.

Thanks

Michael C Mar16-12 03:16 AM

Re: Does the buoyant force change in different fluids?
 
If both objects are floating in equilibrium, the upwards force on each object (buoyant force) must be equal to the downwards force (weight), so you are correct.

The buoyant force is equal to the weight of the amount of fluid displaced, so the object floating on saltwater will displace less fluid and therefore float higher than the object floating on pure water.

Lsos Mar16-12 10:02 AM

Re: Does the buoyant force change in different fluids?
 
However, if the object was fully immersed in water, then the bouyant force WOULD be different.


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