Why Does a Balloon Only Expand at a Certain Air Pressure?

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Discussion Overview

The discussion revolves around the behavior of a balloon during inflation and the factors influencing its expansion at different air pressures. Participants explore the relationship between internal and external pressures, the elasticity of the balloon material, and how these factors change as the balloon is inflated.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether there is a critical air pressure necessary for a balloon to start expanding and seeks a method to calculate this.
  • Another participant suggests that the critical pressure for expansion includes both atmospheric pressure and the pressure from the elastic tension of the rubber, indicating that overcoming this sum is necessary for inflation.
  • A different viewpoint highlights that the thickness of the balloon's material affects the force required for expansion, noting that the balloon is hardest to expand when uninflated and becomes easier to inflate as it expands.

Areas of Agreement / Disagreement

Participants express differing views on the factors affecting balloon expansion, and no consensus is reached regarding the exact nature of the critical pressure or the calculations involved.

Contextual Notes

Some assumptions about the material properties of the balloon and the conditions of inflation are not explicitly stated, and the discussion does not resolve the mathematical relationships involved.

tmv3v
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Notice that when we blow up a balloon, or held up a balloon outside a car and accellerate, the balloon doesn't expand constantly. It seems like there is a critical air pressure for the balloon to start expanding. Is that true and how can we calculate this?
 
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I'd hazard a guess that the critical pressure for expansion is the atmospheric pressure plus the pressure created from the elastic tension in of the rubber acting to compress the air inside. If you can overcome the sum of these pressures when you blow into the balloon, it will expand.
 
The thicker the skin of the balloon of the balloon, the more force it takes to stretch it. But as the balloon expands, its skin gets thinner, so less pressure is required to further expand it. So a balloon is hardest to expand when it's completely uninflated, and once you get it going it keeps getting easier.
 
Thank you so much the explanation is so good:)
 

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