Why Don't Gas Particles Get Pulled Towards Earth If Gravity is Constant?

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    Equilibrium
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Discussion Overview

The discussion revolves around the question of whether gas particles are pulled towards Earth by gravity and the conditions for equilibrium among forces, particularly focusing on the nature of concurrent, non-coplanar forces.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions if three concurrent, non-coplanar forces can be in equilibrium, suggesting that they must be orthogonal and cannot sum to zero.
  • Another participant agrees that three non-coplanar vectors cannot sum to zero but clarifies that they do not have to be orthogonal, emphasizing the concept of linear dependence.
  • Regarding gas particles, one participant states that while gas particles are subject to gravity, other forces, such as collisions, prevent them from falling to the Earth's surface.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the equilibrium of non-coplanar forces, with differing views on the necessity of orthogonality. The discussion on gas particles and gravity also reflects differing perspectives on the forces at play.

Contextual Notes

The discussion includes assumptions about the nature of forces and their interactions, as well as the conditions under which equilibrium can be achieved, which remain unresolved.

rishch
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Can three concurrent, non co planar forces be in equilibrium? also,

If g is a constant then why don't gas particles get accelerated towards the Earth?
 
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I would say no, but it's the sort of question that demands a proof accompanying the answer... I would suggest that three vectors which are not all coplanar must also be orthogonal, and therefore there is no way that they can sum to zero. To answer your second question, gas particles are subject to the force of gravity but there are other forces which stop all the molecules from falling onto the surface (collisions).
 
MikeyW said:
I would say no, but it's the sort of question that demands a proof accompanying the answer... I would suggest that three vectors which are not all coplanar must also be orthogonal, and therefore there is no way that they can sum to zero.

They don't have to be orthogonal. But as you say, they cannot sum to zero. If they did, they would be linearly dependent. And then, any linear combination of the three could be reduced to a linear combination of two of them. Therefore, they would only span a plane, or less, which is against the assumption of not being co-planar.
 
A much better way of saying it! Thanks, orthogonal was the wrong word.
 

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