In what ways do high altitudes affect speed of sound?

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Discussion Overview

The discussion revolves around how high altitudes affect the speed of sound, particularly focusing on the influence of temperature and the mass of gas molecules. Participants explore the relationship between these variables and sound propagation in the atmosphere.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that lower temperatures at high altitudes slow down gas molecules, potentially affecting the speed of sound.
  • The same participant references a formula for the speed of sound that includes the mass of gas molecules, questioning how this mass influences sound velocity.
  • Another participant points out that the mass in the formula refers to the mass of a gas molecule, implying that heavier molecules may decrease the speed of sound due to their greater inertia.
  • The initial poster expresses confusion about the implications of heavier gas molecules on sound velocity, seeking clarification on the relationship between mass and energy transfer.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of gas molecule mass on sound speed, with some clarifying points while others express uncertainty about the underlying mechanics.

Contextual Notes

There are unresolved assumptions regarding the relationship between temperature, mass, and sound velocity, as well as the implications of Newtonian mechanics in this context.

Cluemore
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This is what I am pondering about: At high altitudes, it makes sense that lower temperatures will correspond with velocity of sound traveling through the air at higher altitudes. With lower temperatures the movement of the gas molecules will slow down, making it more difficult for sound to travel through this medium (I am aware that I might be too general in my explanation).

But a formula I came across - ## c_s = \sqrt (\frac{\gamma*k*T} {m}) ## - where ## \gamma ## is the adiabatic exponent, ## k ## Boltzmann's constant, ## T ## the temperature, and ## m ## the mass, seems to indicate to me that there is another variable, ## m ## to consider.

So how could mass of the air affect sound's velocity as it passes through? I don't know. I suppose the mass of the air correspond with the number of air molecules as well as what the air is made up with. Does increasing the number of air molecules decrease the speed of sound? If so, how? Do more particles make it more difficult for energy to travel? If so, why?

PS I apologize if I am asking way too many questions...please tell me so if this is the case!
 
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In your equation, m is the mass of a gas molecule. You could have found that out by looking up "speed of sound" on Wiki. It took me less time to do that than it did for you to write out your question.

Chet
 
Chestermiller said:
In your equation, m is the mass of a gas molecule. You could have found that out by looking up "speed of sound" on Wiki. It took me less time to do that than it did for you to write out your question.

Chet

My goodness...that was a daft thing to do on my part :wink: Made things much clearer but I would like to clarify...

So increasing the mass of gas molecules will decrease the velocity of sound because heavier particles (intuitively and by Newtonian mechanics) would need have the same velocity as lighter particles if both are given the same energy?
 
Clueless said:
My goodness...that was a daft thing to do on my part :wink: Made things much clearer but I would like to clarify...

So increasing the mass of gas molecules will decrease the velocity of sound because heavier particles (intuitively and by Newtonian mechanics) would need have the same velocity as lighter particles if both are given the same energy?
I have no idea what this means. More massive molecules have more inertia than less massive molecules, and require more force to accelerate.

Chet
 

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