Question: Why Does Sound Travel Faster In Solids?
I need your help Tumblr.
Many of you may already know that sound travels faster in denser mediums (gas < liquid < solid). So, the “speed of sound” is not constant (the “speed” scientists refer to is under specific conditions). However, you may not know why the speed changes. And, I think I’m with you.
The typical explanation (at least the one I’ve heard a million times) is that since sound travels by bumping one atom/molecule into the next one, then it travels faster in denser materials, since the atoms/molecules are closer together and so easier to bump into.
Thinking about it the other day, though, I’m not sure that makes any sense at all.
Imagine a billiards table. Each ball represents an atom/molecule. And when one hits the next, it’s propagating the “wave.” If there are two balls, one which I’m hitting into the second, any momentum the second has is a direct result of the first ball hitting it. If the second ball travels 10mph, then the first one must have traveled at least 10 mph as well, since they have the same mass. But if they have the same mass, and would be traveling at the same speed, then would the second ball reach the other side of the table faster than the first one, if the first ball had just traveled there uninterrupted? Here’s a ghetto visual:
====——- …….O ………… O
vs.
====——- …………………. O
In both scenarios the balls are travelling 10mph, except that in the first case, the ball transfers its energy to a second ball, which continues at 10mph.
So, if this basically represents how sound travels - by bumping into other stuff, and sending it careening along - then why does the density effect how quickly it travels? Wouldn’t it travel at the same speed?
What do you say tumblr? Am I making a simple error or am I just missing something? Help me out!
P.s. I love Snow Days =)
Pps. Thanks for the replies so far! Keep ‘em coming! Send a message or email if you’d like!
That said, I understand that solids are many, many molecules packed together, but wouldn’t the logic be the same?
OOOOOOOO
====—— OOOOOOOOOOOOOOO
OOOOOOOO
vs.
O..O..O..O..O
====—— O..O..O..O..O..O..O..O
O..O..O..O..O
(Source: realcleverscience)
