Buoyancy

Archimedes Principle
Any body immersed in a fluid is subjected to an upward force called buoyant force equal to the weight of the displaced fluid.
 

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Archimedes (287-212 B.C.)

 

$BF = \gamma V_D$

 

Where
$BF$ = buoyant force
$\gamma$ = unit weight of fluid
$V_D$ = volume of fluid displaced by the body