Physics geeking

Jay Barracato

Jay Barracato

Graduate Student
Jan 11, 2011
1,528
5
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Solomons MD
I would hope that everyone is familiar with the relationship that wavelength and frequency are inversely proportional and the constant is the speed of sound,

Wavelength X frequency = speed of sound

So the trivia question is

How are these values ( if they are) changed by the transfer of the wave from one medium to another?

In other words, how is the wave from your massive stack of subs behaving in your beer?

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Re: Physics geeking

Very tricky wording of the question, Jay!

The thing is that the speed of sound is not the same for all materials. It travels much faster in water than it does in the air with considerably less loss over distance.

The real challenge here is characterizing the energy transfer between the air and your beer. There will be considerable loss on account of the abrupt change in density between the air and the beer, even more pronounced if your beer is in a glass container versus the ubiquitous "red solo cup" or a single-walled aluminum can (I'm not too familiar with the double walled aluminum bottles, but I would expect them to be somewhere in between.

Another possibly important detail here is that a glass or bottle would be a resonant chamber with an open top.

Also, the beer is quite small in comparison to the frequencies being generated by the subwoofers, I would expect the subwoofers to simply pound the carbonation out of the beer ergo making it flat as a pancake. The heat from the driver's motor structure ends up heating the interior of the cabinet and making the walls of the cabinet warm, which is also conducted to the beer sitting atop the subwoofer.

Nobody likes flat, warm beer.

Ergo, don't put your beer on the subs if you plan on drinking more of it. (Besides, I'll probably come by and toss it in the trash can because my subwoofers are not tables.)
 
Re: Physics geeking

If the speed of sound is faster in water, what happens to the frequency and wavelength?

(Why did Josh compare frequency to the size of the beer?)

Sent from my XT1254
 
Re: Physics geeking

Jay Barracato said:
If the speed of sound is faster in water, what happens to the frequency and wavelength?

(Why did Josh compare frequency to the size of the beer?)

Sent from my XT1254
Click to expand...
The frequency is constant and the wavelength changes..... as you would imagine the faster signal transit covers more distance in the same time one cycle period occurs.

Yes the dissimilar density mediums will cause reflections and incomplete transfer of energy.


JR

PS: Are we doing your home work?
 
Re: Physics geeking

JR- I give homework, not do it.

Actually I was reworking some of my basic wave materials, because I tend to think basic principles when I teach but I was struck by the idea that while frequency remains the same most sound techs think in terms of wavelength.

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