Quiz - Physics - Sound

[saxman242]

Re run your example while keeping the mans displacement the same ... Then the more it weighs the more it sinks. Your example has more than one factor changing. But your argument centers on only one component of the problem.

That's the point...

 

[saxman242]

Im sure there are other factors involved but looking at only the density aspect of things, here is what i got formgooglle searches.

I assume that pine depending on what time of year a whether it is sap or water filled makes a difference and may explain the wide range of the density value.
The more solid things become the higher the speed of sound. Not saying that elasticity has no play in this ,,,,,,,it is an important factor in sound transmission.

i looked up speed of sound for _________ then density of ________ here are the numbers

Material ---- density ---- speed
--------------- kg/m3 ---- meters

AIR ------------- 1.3 ------------- 343
WATER ---------- 997 -------------1500
PINE ------------ 350 - 850 ------ 4000
STEEL ----------- 8050 ------------- 6000

Saying "denser objects tend to have a higher speed of sound" and saying "objects have a higher speed of sound BECAUSE they are denser" are not the same thing

 

[captain]

As a retired submarine sonarman,,,,, some of this very entertaining.

this sounds like the argument that ,,,,,hot electric stove element did not cause the blister the fluid in the body going to he skin surface did.

As a retired ASW aircraft sonar operator I was looking for you.

 

[Angelo Farina]

Re run your example while keeping the mans displacement the same ... Then the more it weighs the more it sinks. Your example has more than one factor changing. But your argument centers on only one component of the problem.

Exactly....
Same as with density and bulk modulus for the sound speed. Someone here is looking only at density, while what matters is the ratio between the bulk modulus and density. If you just look at density you desume, erroneously, that sound speed is greater when density is large.
Exactly as in my example one desumes erroneously the buoyancy increases when weight is large.

 

[NAM001]

As a retired ASW aircraft sonar operator I was looking for you.

prpobably so they probably told us where to be so you could find us. Just teasing. It was a fun job for sure. P3 guy I am guessing?

 

[NAM001]

Saying "denser objects tend to have a higher speed of sound" and saying "objects have a higher speed of sound BECAUSE they are denser" are not the same thing

True that is a deliniation that is not taught in diving or anything else outside of speciality training. Again diving is a very basic level.knowledge when it comes to such things.

 

[Rickk]

Speed of Sound in Water - The Physics Factbook

"Sound is a type of longitudinal, mechanical wave. They need a medium to propagate and will not travel through a vacuum. Sound travels at different speed in different media. The speed of sound is determined by the density (ρ) and compressibility (K) of the medium. Density is the amount of material in a given volume, and compressibility is a measure of how much a substance could be compacted for a given pressure. The denser and the more compressible, the slower the sound waves would travel. Water is much more dense than air, but since it is nearly incompressible the speed of sound is about four times faster in water than in air."

So D is closest to the correct answer. Speed of sound is roughly 4 times as fast but not because of density but because of incompressability.

Saying "denser objects tend to have a higher speed of sound" and saying "objects have a higher speed of sound BECAUSE they are denser" are not the same thing

Both are incorrect. Density is inversely related to speed of sound., A denser medium will have a lower speed of sound, given the same compresability.

I have worked on a lot of construction jobs that involved blasting. The speed of sound through rock is higher than in air, more dense but rocks are not easily compressed. You feel the blast through your feet before you hear the sound of the blast.

 

[tursiops]

given the same compresability

This is the flaw in ALL these arguments...the media of different densities do NOT have the same compessibility.

 

[NAM001]

Speed of Sound in Water - The Physics Factbook

"Sound is a type of longitudinal, mechanical wave. They need a medium to propagate and will not travel through a vacuum. Sound travels at different speed in different media. The speed of sound is determined by the density (ρ) and compressibility (K) of the medium. Density is the amount of material in a given volume, and compressibility is a measure of how much a substance could be compacted for a given pressure. The denser and the more compressible, the slower the sound waves would travel. Water is much more dense than air, but since it is nearly incompressible the speed of sound is about four times faster in water than in air."

So D is closest to the correct answer. Speed of sound is roughly 4 times as fast but not because of density but because of incompressability.



Both are incorrect. Density is inversely related to speed of sound., A denser medium will have a lower speed of sound, given the same compresability.

I have worked on a lot of construction jobs that involved blasting. The speed of sound through rock is higher than in air, more dense but rocks are not easily compressed. You feel the blast through your feet before you hear the sound of the blast.

Yes Rikk that is right. it is a matter of which ((density or compressibility)) is the predominant driving factor on the end result. because temp and other factors also effect Speed of sound such as depth which for discussion purposes is moot because none of us dive in the depth range where pressure has an effect.

From years ago training Speed of sound is controlled by 3 factors temp pressure and salinity. There are more of course,, but those other factors are moot unless you are comparing water salt or fresh to some substance other than water, where they now have an influence in its effect.. until you do those other factors are a wash.

 

[saxman242]

to suggest that making something heavier will allow it to float is a falicy.

To suggest that making something denser will allow sound to travel faster through it is also a fallacy. That's the point.