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Buoyancy

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Buoyancy


Question: If a block of wood floats in a pail of water with weight sitting 
on top of it, the waterline say is at the halfway point of the wood block.  If 
we hand the weight from below the block -- into the water, will the water 
level on the block stay the same, increase, or go down.
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You are correct that the water displaced should remain the same, 
and therefore the water level on the block should go down.  (since the weight 
is displacing a little bit of water itself).  This should be easy to test 
though - how about doing the experiment to check it?

A. Smith
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If you hang the weight below the block, the water level will no 
longer reach exactly halfway up the block, but will reach slightly less than 
halfway up depending on the density of the weight.  It is correct to say that 
the weight supported by the buoyant force is the same whether the weight is on 
top, or below, the block.  Also, the water displaced is the same in both 
cases.  The difference is that the weight displaces water when it is hung 
under the block, but not when it is placed on top.

Mooney
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