A video camera in an air filled underwater housing is ballasted to be neutrally buoyant. Does not sink, does not float.

 

Will removing a 200 grams (dry) ballast weight from inside the housing result in a more, less or equal amount of flotation if the same 200 grams weight is removed from ballast attached outside (wet) ?

 

Miguel

Cool question. You ought to read my thread in Engineering on 'floating stones'. Yes, you can suspend the mass in the water and displace that much more water. What's the specific gravity of the mass?

inside ballast will give more floatation as the volume of the vessel will remain a constant. removing the wet ballast will result in less as althought the mass decrease is the same there is also some loss of volume as well.

If you have the excess draft. Maybe I did not catch the subtlety of the opening question, but the path is clear. For a ballast of some S.G.>1, we account for total volume. Ah, I converge with what Insane Alien said.

A video camera in an air filled underwater housing is ballasted to be neutrally buoyant. Does not sink, does not float.

 

Will removing a 200 grams (dry) ballast weight from inside the housing result in a more, less or equal amount of flotation if the same 200 grams weight is removed from ballast attached outside (wet) ?

 

Miguel

Buoyancy is based on the amount of liquid displaced, if the weight is outside the housing than the displacement and buoyancy will increase.