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Great - now I'm beginning to understand!!!
If there is no water under the box we can't call the upward force
Buoyancy even tho it's still equal to the weight of the displaced
water.
If we let a monolayer of water seep under the box (but keep it tied
down with a thread) we can then call the upward force Buoyancy. Same
amount of force - different name. OK.
Thanx Bill - this clears things up nicely.
At 7:24 PM -0600 11/3/10, William Robertson wrote:
I agree that the bottom will flex up under the box, but for reasons_______________________________________________
outlined by others. The pressure exerted on the bottom of the aquarium
just below the box is less than the pressure exerted on the aquarium
bottom all around it. Not because of a buoyant force on the box,
because you have removed the mechanism for that force, but because
there is "less water" above that part of the bottom of the aquarium.
And yes, it will be equal to the weight of the water displaced, but
that doesn't mean it's a buoyant force pushing up on the box.
Bill
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
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