What does it mean for a bubble to be in equilibrium?

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    Bubble Equilibrium Mean
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Discussion Overview

The discussion revolves around the concept of equilibrium in soap bubbles, particularly focusing on the balance of forces and the role of surface tension. Participants explore the mechanics involved in bubble formation and stability, with references to related physics concepts.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests that equilibrium for a bubble means the forces expanding and compressing it are equal, maintaining a steady radius.
  • Another participant inquires whether the discussion pertains to gas bubbles in liquids or soap bubbles in air, indicating a potential distinction in the types of bubbles being considered.
  • A participant notes that the pressure inside a soap bubble is greater than the pressure outside, with the difference balanced by a circumferential force due to surface tension.
  • There is a mathematical expression provided for the pressure inside the bubble, suggesting that as the bubble expands, the relationship between internal pressure and radius may change, raising questions about whether pressure remains constant or if it adjusts with radius changes.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the specifics of bubble equilibrium, with multiple viewpoints on the mechanics and definitions involved. The discussion remains unresolved regarding the implications of changing radius on internal pressure.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the types of bubbles and the specific conditions under which equilibrium is analyzed. The mathematical relationships presented are not fully resolved.

Who May Find This Useful

This discussion may be useful for individuals interested in fluid mechanics, surface tension, and the physics of bubbles, particularly in the context of soap bubbles and their properties.

Matthollyw00d
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What does it mean for a bubble to be in equilibrium?
I assumed it just meant that the forces expanding it and the forces compressing it were equal, hence it was at a steady radius. Is there more to it than that?
I'm working on an EM problem so I don't think the specifics are important, I just need some general knowledge on bubbles (and I have none, besides common intuition). Any information pertaining to surface tension would be the most relevant.
Thanks.
 
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Prof. Julius Sumner miller has a cool video on soap bubbles .

 
Last edited by a moderator:


Are you referring to bubbles of gas in a liquid, and if so from dissolved gas those formed when the liquid boils.

or

Are you referring to soap bubbles in air?
 


Interesting video. Not really helpful, but interesting none-the-less.
EDIT:
Soap bubbles
 


OK. So we have a soap bubble, with P_0 outside the bubble \gamma for a surface tension on the bubble. So the Pressure inside denoted
P_A:=\frac{4\gamma}{R}+P_0.
Now if that bubble expands say to a radius, S for whatever reason, does P_A remain constant inside, to give me a set of equations? Or does the
F_A:=P_A(4 \pi R^2) remain constant and the P_A adjust for the changing radius?
 


cragar said:
Prof. Julius Sumner miller has a cool video on soap bubbles .



This guy is my hero!

I wish I had a teacher that was this exciting!
 
Last edited by a moderator:


Ya Julius is pretty amazing ,
 

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