Re: [Phys-l] buoyancy on a submerged pole

[Chuck Britton <cvbritton@embarqmail.com>]

How about two identical aquaria - each filled to the rim.
One has an empty box glued to its bottom.

My claim is that the box will cause that piece of glass to flex less.

Maybe it will, maybe t won't.
My expectation is that the 'boxed' bottom will flex less.
The 'unboxed' bottom could be made to closely match the 'boxed' 
bottom if one would push up on its center with a force equal to the 
'weight of water that the box is displacing' in the other aquarium.


At 6:56 PM -0600 11/3/10, William Robertson wrote:
> I've been watching from the sidelines on this. Here's how I see it. 
> The buoyant force is exerted by a fluid on objects partially or 
> entirely submerged in them. You can calculate this by using the weight 
> of the fluid displaced, but the mechanism for the force is the 
> pressure difference between the bottom and top of the object. No 
> gravity--no buoyant force, because no pressure difference. Now if your 
> box does not allow any fluid beneath it, then you have removed the 
> mechanism for the buoyant force. There is no buoyant force, and the 
> weight of the displaced fluid means nothing.
>
> Am I missing something?