Why Does a Bubble Move to the Middle in a Horizontal Pipe?

[vladim1]

Hi people.

Please explain me, why in a horisontal pipe (closed) a bubble go to middle, and not stay in any other position?

Also what is the difference of forces when this bubble moves from right/left to middle and when it rise from bottom to top.


I know bubble rise due to buoyancy, which is equal with pgV. But in horisontal case, this force seems to be less.

Thanks.

 

[vladim1]

Hello,
is this question so difficult?? At least, pleas, can someone explain me how spirit level works.

 

[A.T.]

Hello,
is this question so difficult?? At least, pleas, can someone explain me how spirit level works.

The inside of the spirit level pipe is not a perfect cylinder, but rather a barell:
http://en.wikipedia.org/wiki/Spirit_level