In what ways do high altitudes affect speed of sound?

In summary, at high altitudes, lower temperatures slow down the movement of gas molecules, making it more difficult for sound to travel through the medium. The formula ## c_s = \sqrt (\frac{\gamma*k*T} {m}) ## indicates that the mass of gas molecules is a factor in determining the velocity of sound. Increasing the mass of gas molecules will decrease the velocity of sound due to their higher inertia.
  • #1
Clueless
26
2
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!
 
Physics news on Phys.org
  • #2
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
 
  • #3
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?
 
  • #4
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
 

1. How does air density at high altitudes affect the speed of sound?

As altitude increases, air density decreases. This means that there are fewer molecules in the air to transmit sound waves, resulting in a decrease in the speed of sound.

2. Does temperature have an impact on the speed of sound at high altitudes?

Yes, temperature does have an impact on the speed of sound at high altitudes. In general, as temperature increases, the speed of sound also increases. However, at extremely high altitudes where temperatures are very low, the speed of sound can actually decrease due to the decrease in air density.

3. How much does the speed of sound decrease with each increase in altitude?

The decrease in speed of sound with each increase in altitude varies depending on factors such as air temperature and humidity. On average, the speed of sound decreases by about 1% for every 330 meters increase in altitude.

4. Why does the speed of sound decrease at higher altitudes?

The speed of sound decreases at higher altitudes because there are fewer molecules in the air to transmit the sound waves. This results in a decrease in air density, which in turn affects the speed at which sound can travel.

5. How does the speed of sound at high altitudes affect aircraft travel?

The decrease in speed of sound at high altitudes can affect aircraft travel in several ways. It can result in a decrease in engine performance, as the engines need to work harder to produce the same amount of thrust. It can also affect the efficiency of communication systems, as sound travels slower and can cause delays in communication between pilots and air traffic control. Additionally, this decrease in speed of sound can also lead to changes in the aerodynamics of the aircraft, which can impact its overall performance and stability.

Similar threads

B What sound frequencies can pass through a hole in a wall?
    • Mechanics
Replies
31
Views
710
Why Can a Sound Wave Not Travel Faster than the Average Molecule Speed?
    • Mechanics
Replies
23
Views
2K
Speed of sound in steel vs air
    • Mechanics
Replies
7
Views
2K
Adiabatic approximation in the derivation of the speed of sound
    • Mechanics
Replies
6
Views
2K
Exploring Sound in Low Atmosphere: Speed, Intensity, and Frequency
    • Mechanics
Replies
1
Views
7K
Curiosity - Relative speeds in relation to the sound barrier?
    • Mechanics
Replies
8
Views
997
Exactly how do pressure waves work at the molecular level?
    • Mechanics
2
Replies
49
Views
3K
Confusion regarding the speed of sound in wind
    • Mechanics
Replies
11
Views
4K
I Modeling a Bottle Rocket: Analyzing the Maximum Altitude
    • Mechanics
Replies
4
Views
2K
Pressure felt by a piston, Mach number of speaker making the sound
    • Mechanics
Replies
14
Views
2K

Hot Threads

Recent Insights

Back
Top