velocity of sound and light

[laya533]

---

Members do not see this ad.

where is the velocity of sound higher? in water or solid? what about velocity of light? can you please explain them for me? thanks

 

[cheapdate]

where is the velocity of sound higher? in water or solid? what about velocity of light? can you please explain them for me? thanks

light's the fastest.. sound travels faster in solid than in water.. think of solid as more rigid structure (denser) --> better signal transduction.

 

[cfdavid]

Yeah, just think of being underwater in a swimming pool. You can hear the quarter drop and "ping" off the bottom of the concrete pool. But, you wouldn't be able to hear that in the air.

Also, for solids, just think of putting your ear to the railroad tracks to get a feel for how far the train is.

 

[Shrike]

I think laya probably knew that light goes faster than sound; I really doubt that was the question, cheap.

For sound, the above posters are right -- tightly-bonded molecules make for fast transmission of compression waves (read: sound). Hence, liquids are better than gases, and solids, particularly hard solids, are better than that. Still, you do not have to know this for the MCAT -- relevant speeds of sound will always be given, even for air.

By the way, to cf: hearing the ping of the quarter underwater has nothing to do with the speed of sound, but with energy absorbtion, something we never worry about on the MCAT (and also with movement of the wave from the water to the air, with attendant reflection, if that's the situation you were thinking about). The higher speed of sound in water is the reason you have trouble figuring out the direction from which an underwater sound came -- not as much time difference between arrival of the sound at your ears. And the railroad tracks: again, that's energy loss, not rate of transmission.

For light, just remember, for our purposes: (1) light never goes faster than the speed of light (you laugh, but experiments last year proved otherwise for tiny distances under weird circumstances; (2) air is the same as vacuum, pretty much, so again light goes at the speed of light (on the MCAT); and (3) it goes slower in other stuff. How much slower, forget about -- there's no intuitive way for the nonexpert to know, and they always give you the values.

Shrike
TPR physics, verbal, bio

 

[cfdavid]

I think laya probably knew that light goes faster than sound; I really doubt that was the question, cheap.

For sound, the above posters are right -- tightly-bonded molecules make for fast transmission of compression waves (read: sound). Hence, liquids are better than gases, and solids, particularly hard solids, are better than that. Still, you do not have to know this for the MCAT -- relevant speeds of sound will always be given, even for air.

Thanks for clearing up the water and railroad sound versus energy statement. I was going to get into the whole bulk modulus thing, but didn't think it would be so relevant for the MCAT. I guess the best way to conceptualize it is as you stated, that the more tightly bound the molecules, the more they are able to transmit the longitudinal wave.

I think it can get quite complicated, in fact, but I'm not going to worry about all the exceptions to the rules right now.

 

[Shrike]

I think it can get quite complicated, in fact, but I'm not going to worry about all the exceptions to the rules right now.

Bravo. This is absolutely best for the MCAT.

Note to others: any references to bulk modulus, or any other modulus, in a discussion of sound, and we're gonna have to come to your house. Don't be a messin' with the SDNers.

 

[laya533]

Bravo. This is absolutely best the MCAT.

Note to others: any references to bulk modulus, or any other modulus, in a discussion of sound, and we're gonna have to come to your house. Don't be a messin' with the SDNers.

Thanks so much shrike for always giving the best answer