Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: vacuum floats?

Learn more physics!

Most recent answer: 10/22/2007
Q:
A sphere filled with a gas will float in a medium less dense like water. I wonder will that same sphere float if the gas is removed and only a vacuum remains. I suspect that the activity of the gas is the reason for its buoyancy and that the sphere will sink as the gas vacates.
- james
texas
A:
Nope, the sphere floats just because it weighs less than the same volume of water, as Archimedes realized. If you evacuate the sphere, it will actually float just a tiny bit higher (air has some weight), assuming that it doesn't implode from the pressure difference between outside and inside.

Mike W.

(published on 10/22/2007)

Follow-up on this answer.