IIT JEE , AIEEE Forum - Physics , Mechanics - ARCHIMEDES PRINCIPLE-RATES ASSURED

madman

well look
when i immerse an object into water three things can happen
1.the object stays there
2.the object sinks
3.the object moves up

consider the water in a cylinder
consider a water element of arbitary shape some where in the centre
the net force on this water element is zero
because P(bottom)-p(top)=mg

suppose i displace of this water by a stone
the net force(buoyant) acting is still P(bottom)-P(top) = weight of displaced water

suppose the density of the stone is equal to that of water
buoyant force = Den(water)*volume*g = Den(stone)*volume*g = weight of stone

suppose density of stone is lesser than water
Den(stone)*volume*g < Den(water)*volume*g
hence the buoyant force exceeds the weight
AND THE OBJECT MOVES UP
simillarly when density of stone is greater than water the stone will sink
when the stone floats in water its weight is balanced by the buoyant force
therefore
buoyant force=weight of stone = density of fluid x volume x g
hope you got it

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