speed of sound


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Topic: Science > Physics
User: "John Doe"
Date: 06 Apr 2006 11:47:25 AM
Object: speed of sound
The speed with which sound waves in the air pass a stationary observer
depends on the
(A) speed of the air relative to the observer
(B) speed of the source relative to the air
(C) frequency of the source
(D) wavelength of the sound in the air
(E) intensity of the sound in the air
speed of sound = square root of k*p/air density= square root of k*R*T/M
K (kappa) = adiabatic index
T = absolute temperature
R = constant
if medium is solid it also depends on stiffness.
I don't see any of these varibles in one of the answer choices.
.

User: ""

Title: Re: speed of sound 06 Apr 2006 12:34:18 PM
Are you related to THE John Doe?
.

User: "tadchem"

Title: Re: speed of sound 06 Apr 2006 08:43:19 PM
John Doe wrote:

The speed with which sound waves in the air pass a stationary observer
depends on the

{*Where* did you find this stuff?]

(A) speed of the air relative to the observer

"Stationary" in the context of discussions of the speed of sound
usually means 'stationary with respect to some fixed frame of
reference.' This is not necessarily true of the air. Wind can affect
the apparent speed of sound of air relative to the observer.

(B) speed of the source relative to the air

This results in a doppler frequency shift, not in a change of the speed
of sound.

(C) frequency of the source

Frequency is independent of velocity - at least in the range of what is
normally called sound.

(D) wavelength of the sound in the air

Wavelength is also independent of speed. The *product* of frequency
and wavelength equals speed.

(E) intensity of the sound in the air

Unless the intensity of the sound is so great that the dynamic pressure
varies beyond the limits of an ideal gas (due to heat capacity ratios,
among other things) - the pressure variation is independent of the
velocity.

speed of sound = square root of k*p/air density= square root of k*R*T/M
K (kappa) = adiabatic index
T = absolute temperature
R = constant

kappa is the heat capacity ratio - C(p) / C(v) - the ration of the heat
capacity at constant pressure to the heat capacity at constant volume.
This is also called the adiabatic index, and directly affects the way
the gas responds to pressure changes that are too fast to allow thermal
equilibration.

if medium is solid it also depends on stiffness.

"Solid" air - now *that* would be an interesting research material.

I don't see any of these varibles in one of the answer choices.

Look here:
http://scienceworld.wolfram.com/physics/SpeedofSound.html
Tom Davidson
Richmond, VA
.

User: "Sam Wormley"

Title: Re: speed of sound 06 Apr 2006 12:06:18 PM
John Doe wrote:

The speed with which sound waves in the air pass a stationary observer
depends on the
(A) speed of the air relative to the observer
(B) speed of the source relative to the air
(C) frequency of the source
(D) wavelength of the sound in the air
(E) intensity of the sound in the air

speed of sound = square root of k*p/air density= square root of k*R*T/M

K (kappa) = adiabatic index
T = absolute temperature
R = constant

if medium is solid it also depends on stiffness.

I don't see any of these varibles in one of the answer choices.


Remember that sound is a mechanical wave. Tell us the reason for each of
the answers you rule out.
Background
http://en.wikipedia.org/wiki/Speed_of_sound#Speed_in_ideal_gases_and_in_air
.
User: "John Doe"

Title: Re: speed of sound 06 Apr 2006 01:03:50 PM
A makes no sense because the observer is stationary.
B makes no sense
C lambda * frequency = speed. So I guess C is possible
D lambda * frequency = speed So D is also possible
E intensity doesn't make anything go faster
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:eUbZf.879639$x96.432005@attbi_s72...

John Doe wrote:

The speed with which sound waves in the air pass a stationary observer
depends on the
(A) speed of the air relative to the observer
(B) speed of the source relative to the air
(C) frequency of the source
(D) wavelength of the sound in the air
(E) intensity of the sound in the air

speed of sound = square root of k*p/air density= square root of k*R*T/M

K (kappa) = adiabatic index
T = absolute temperature
R = constant

if medium is solid it also depends on stiffness.

I don't see any of these varibles in one of the answer choices.


Remember that sound is a mechanical wave. Tell us the reason for each of
the answers you rule out.

Background

http://en.wikipedia.org/wiki/Speed_of_sound#Speed_in_ideal_gases_and_in_air

.
User: "Sam Wormley"

Title: Re: speed of sound 06 Apr 2006 01:22:58 PM
John Doe wrote:

A makes no sense because the observer is stationary.

But not with respect to the gas through which the sound is propagating.

B makes no sense
C lambda * frequency = speed. So I guess C is possible
D lambda * frequency = speed So D is also possible
E intensity doesn't make anything go faster

B-D don't appear in your equations.


"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:eUbZf.879639$x96.432005@attbi_s72...

John Doe wrote:

The speed with which sound waves in the air pass a stationary observer
depends on the
(A) speed of the air relative to the observer
(B) speed of the source relative to the air
(C) frequency of the source
(D) wavelength of the sound in the air
(E) intensity of the sound in the air

speed of sound = square root of k*p/air density= square root of k*R*T/M

K (kappa) = adiabatic index
T = absolute temperature
R = constant

if medium is solid it also depends on stiffness.

I don't see any of these varibles in one of the answer choices.


Remember that sound is a mechanical wave. Tell us the reason for each of
the answers you rule out.

Background

http://en.wikipedia.org/wiki/Speed_of_sound#Speed_in_ideal_gases_and_in_air




.
User: "John Doe"

Title: Re: speed of sound 06 Apr 2006 01:48:02 PM
ok thanks. I got it. A is the right answer because air is the medium for the
sound.
"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:60dZf.879724$x96.711609@attbi_s72...

John Doe wrote:

A makes no sense because the observer is stationary.


But not with respect to the gas through which the sound is propagating.


B makes no sense
C lambda * frequency = speed. So I guess C is possible
D lambda * frequency = speed So D is also possible
E intensity doesn't make anything go faster


B-D don't appear in your equations.


"Sam Wormley" <swormley1@mchsi.com> wrote in message
news:eUbZf.879639$x96.432005@attbi_s72...

John Doe wrote:

The speed with which sound waves in the air pass a stationary observer
depends on the
(A) speed of the air relative to the observer
(B) speed of the source relative to the air
(C) frequency of the source
(D) wavelength of the sound in the air
(E) intensity of the sound in the air

speed of sound = square root of k*p/air density= square root of k*R*T/M

K (kappa) = adiabatic index
T = absolute temperature
R = constant

if medium is solid it also depends on stiffness.

I don't see any of these varibles in one of the answer choices.


Remember that sound is a mechanical wave. Tell us the reason for each
of
the answers you rule out.

Background

http://en.wikipedia.org/wiki/Speed_of_sound#Speed_in_ideal_gases_and_in_air



.
User: "CWatters"

Title: Re: speed of sound 07 Apr 2006 02:10:33 AM
"John Doe" <johndoe@nothing.edu> wrote in message
news:CndZf.99$An2.64@newsread2.news.pas.earthlink.net...

ok thanks. I got it. A is the right answer because air is the medium for

the

sound.

Yes think "observer moving through air with sound in it" and Google Doppler
effect.
.






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