Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: dominic horath on 10/06/2008 09:16:01

Title: Why does air remain inside a submerged bottle?
Post by: dominic horath on 10/06/2008 09:16:01: dominic horath asked the Naked Scientists:

Hello guys.

I have a question regarding the way a beer bottle (or any similar shaped bottle) behaves in water. Why is it that if the bottle is submerged right side up water will flow in immediately but if the bottle is submerged upside down the air stays in the bottle perfectly well?

Thank you,
Dominic. from California

What do you think?
Title: Why does air remain inside a submerged bottle?
Post by: Madidus_Scientia on 10/06/2008 10:00:23: Because the air floats, so it can't go down.
Title: Why does air remain inside a submerged bottle?
Post by: lyner on 10/06/2008 11:04:32: If the bottle is upside down, the air has nowhere to go- the water pushes it up to the top (i.e. the 'bottom' of the bottle).
Title: Why does air remain inside a submerged bottle?
Post by: syhprum on 10/06/2008 14:10:25: what would happen if the bottle was submerged to such a depth that the air that normally has a density 1/800th that of water was compressed by the virtually uncompressable water so that its density was greater than the water ?
Title: Why does air remain inside a submerged bottle?
Post by: lyner on 10/06/2008 16:10:31: Ah well - that's a typical TNS response!
I guess it would have dissolved long before that situation?
The answer can't just be that it would flow out of the neck of the bottle, can it?
Title: Why does air remain inside a submerged bottle?
Post by: LeeE on 10/06/2008 18:43:51: I believe that the compressability of air, when used to provide bouyancy, is an issue in the design of deep-sea diving bathyscapes and instead, petrol is used.

http://en.wikipedia.org/wiki/Bathyscape (http://en.wikipedia.org/wiki/Bathyscape)
Title: Why does air remain inside a submerged bottle?
Post by: syhprum on 10/06/2008 20:16:24: Simple calculation shows that one would have to descend 8000 meters for the air to become as dense as water assuming the water maintains its normal density.
I believe there are parts of the ocean this deep but it would be interesting to perform the experiment in a pressure chamber if one was available.
Title: Why does air remain inside a submerged bottle?
Post by: qazibasit on 13/06/2008 14:01:04: it remains inside the bottle only till the inlet of the bottle is downwards towards the base of the water table and the base of the container is directed towards the surface of the water table. it is because of the movement of air molecules directed upward in the container and not getting anywhere to escape.