# Velocity of sound in Carbon Diox vs. Air

## Homework Statement

An organ pipe is blown with carbon dioxide and produces waves 2 ft long and a note with a frequency if 350 Hz. What is the velocity of sound in carbon dioxide? How do you account for the fact that this is not the same as the velocity in air?

## Homework Equations

Wavelenght=velocity/frequency therefore Velocity=wavelength*frequency.

## The Attempt at a Solution

Velocity =2ft*350HZ=213.36 m/s

My teacher wants the answer in the same units as the question, but 700 ft/Hz doesn't seem like a true meausrement? Which is why I put 213.36 m/s? I am on track here?

Also, would this velocity be different than that of air b/c carbon dioxide is heavier and denser than air?

Related Introductory Physics Homework Help News on Phys.org
Yes and that is because v = sqrt( krt/m0) where k stands for adiabatic exponent.

vela
Staff Emeritus
Homework Helper

## Homework Statement

An organ pipe is blown with carbon dioxide and produces waves 2 ft long and a note with a frequency if 350 Hz. What is the velocity of sound in carbon dioxide? How do you account for the fact that this is not the same as the velocity in air?

## Homework Equations

Wavelenght=velocity/frequency therefore Velocity=wavelength*frequency.

## The Attempt at a Solution

Velocity =2ft*350HZ=213.36 m/s

My teacher wants the answer in the same units as the question, but 700 ft/Hz doesn't seem like a true meausrement? Which is why I put 213.36 m/s? I am on track here?
What's wrong with ft/s?
Also, would this velocity be different than that of air b/c carbon dioxide is heavier and denser than air?
That's one reason. What else does the speed of sound in a gas depend on, and is it or are they different for CO2 compared to air?

What's wrong with ft/s?

That's one reason. What else does the speed of sound in a gas depend on, and is it or are they different for CO2 compared to air?
How would you convert: 213.36 m/s into ft/s?

Thanks for the tip!
The speed of a gas also depends on its temperature. (Velocity increases with temperature. Temperature also affects density the higher the temp, the lower the density.) Therefore, the velocity of carbon dioxide would differ from air b/c of differences in temperatures based on the kinetic energy of molecules in the air and CO2.

[To convert 213.23 m/s to ft/s we would get: (213.36 m/s)( 3.2808399)= 700 ft/s]

Correct?

[To convert 213.23 m/s to ft/s we would get: (213.36 m/s)( 3.2808399)= 700 ft/s]

Correct?
Yes you really didn't need to do that since 2*350 = 700

Yes you really didn't need to do that since 2*350 = 700
So i can leave it in m/s? Where did the 350 come from?

So i can leave it in m/s? Where did the 350 come from?
You should know you calculated it yourself in your first post.

Velocity =2ft*350HZ = 700 ft/s

Hz is defined as s-1 "per second"

You should know you calculated it yourself in your first post.

Velocity =2ft*350HZ = 700 ft/s

Hz is defined as s-1 "per second"
gosh-sometimes you miss the obvious staring at you. thanks!

Therefore, the velocity of carbon dioxide would differ from air b/c of differences in temperatures based on the kinetic energy of molecules in the air and CO2.
Assume the carbon dioxide is the same temperature as air, because you're not told otherwise.

Consider that air is mostly N2.

For a given amount of kinetic energy (temperature), how does the velocity of a nitrogen molecule compare to that of a carbon dioxide molecule?