Archimedes principle with a completely submerged ball

AI Thread Summary
A ball inflated with air will not sink in water due to the upward buoyant force created by the pressure difference, which is greater below the ball than above it. When completely submerged, the pressure underneath the ball is indeed higher because it is deeper in the water, ensuring that it remains submerged. The discussion also touches on the behavior of other objects, like a box resting on the pool bottom, questioning whether they would remain down without upward pressure. It is noted that achieving a complete seal to prevent water from entering a submerged container is theoretically possible but practically challenging. Overall, the principles of buoyancy and pressure dynamics in fluids are central to understanding these scenarios.
dasky
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Greetings,
I have a question about the classic Archimede's principle.
A ball inflated with air will not sink into water. My understanding is that it will be pushed from all directions by the surrounding water trying to fill the space occupied by the ball. So there will be a pressure downwards formed by the water column above the ball, and there will be pressure upwards from the water below the ball, and obviously on the sides.
My question is: if a ball is completely submerged there will be a lot of pressure downwards but no or very little pressure upwards, will the ball remain submerged?
Thanks
Dasky
 
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dasky said:
My question is: if a ball is completely submerged there will be a lot of pressure downwards but no or very little pressure upwards,
No, your premise is wrong. The pressure is higher at the bottom of the ball (it is deeper and pressure grows linearly with depth).
 
Then what about a different container, like a box, resting on the bottom of a pool? the face in contact with the surface of the pool will have no water pushing upwards, so will it remain down?
 
dasky said:
Greetings,
I have a question about the classic Archimede's principle.
A ball inflated with air will not sink into water. My understanding is that it will be pushed from all directions by the surrounding water trying to fill the space occupied by the ball. So there will be a pressure downwards formed by the water column above the ball, and there will be pressure upwards from the water below the ball, and obviously on the sides.
My question is: if a ball is completely submerged there will be a lot of pressure downwards but no or very little pressure upwards, will the ball remain submerged?
Thanks
Dasky
The pressure under the ball will be greater because it is deeper.
By the way, I have noticed that if such a ball is pushed down under water and then released, the upward acceleration cannot exceed -g. This is because water has to fall by gravity into the space vacated in order to create the upthrust.
 
dasky said:
Then what about a different container, like a box, resting on the bottom of a pool? the face in contact with the surface of the pool will have no water pushing upwards, so will it remain down?

If you can arrange it such that really no water slips in. This is difficult, but a priori possible.
 

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