Light and sound waves question

[stuw]

So just wanted to clear something up...

Sound waves (and pressure waves) are longitudinal and they have greater speed in mediums that resist compression and are not very dense. However, sound waves travel faster through solids than liquids and gases. Why is this?

Also, is there any other similar rule to light waves? All I know is that light waves are transverse and are fastest through air vacuums.

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[brood910]

Sound travels faster in denser medium (solid > liquid > gas), actually. It's because in sqrt (B/density), B increases faster than density does.
However, when you are talking about GAS, sound travels more slowly when it's in a denser medium.
This is because in gas, Vsound = sqrt (YP/density) = KE (restorative force)/inertia
As temperature goes up, KE goes up = faster even though it's less dense when it's a GAS.

Edited last sentence.

 

[scrub2scrubs]

Sound travels faster in denser medium (solid > liquid > gas), actually. It's because in sqrt (B/density), B increases faster than density does.
However, when you are talking about GAS, sound travels more slowly when it's in a denser medium.
This is because in gas, Vsound = sqrt (YP/density) = KE (restorative force)/inertia
As temperature goes up, volume goes up as well = less dense = slower when it's a GAS.

great technical explanation, I had no idea those equations existed.

If you want to conceptualize it a little more try to imagine sound waves as a result of back and forth vibrations of the particles in the medium..this is what propagates the sound waves forward. In a solid, the particles want to keep their particles intact and have a lot more inertia due to a lattice structure for example, so they vibrate forward and then move back to their original position more quickly. this causes the sound waves to be propagated through the medium more quickly.

 

[stuw]

You two are awesome. Thank you (also didn't know those equations existed either haha)

 

[stuw]

Apologies, one more clarification question:

So for the equation: sqrt (B/density)

We can justly say that sound waves will travel faster in solid material than liquid and gas, but if asked between two medium (one being more dense than the other), the sound wave will travel faster in the less dense material, right?

 

[brood910]

Apologies, one more clarification question:

So for the equation: sqrt (B/density)

We can justly say that sound waves will travel faster in solid material than liquid and gas, but if asked between two medium (one being more dense than the other), the sound wave will travel faster in the less dense material, right?

Only when you are comparing two different GASEOUS media.

 

[scrub2scrubs]

Only when you are comparing two different GASEOUS media.

Because the bulk modulus for both gases will be relatively small?