Help Needed: Wave Frequency & Wavelength vs. Air Temp

In summary: C is a function of temperature. Plug in the numbers and solve. The other 2 are equally simple. In summary, this conversation discusses the relationship between sound waves and air temperature. The individual is trying to find the air temperature based on the given frequency and wavelength of a sound wave. They use Google to find the speed of sound at different temperatures and ultimately determine that the temperature is likely 15 degrees C based on their calculations. They also mention using a formula to calculate the speed of sound based on temperature, but struggle to find the correct one.
  • #1
Dark Visitor
215
0
A sound wave in air has a frequency of 500 Hz and a wavelength of .68 m. What is the air temperature?

* -18 degrees C
* 0 degrees C
* 15 degrees C
* 27 degrees CI can't find an equation for this, and I don't know how to solve it. Anyone know anything about this? Please help me. Thanks.
 
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  • #2
Try googling for speed of sound. It varies with temp. So compute the speed from the data and compare with what you find online. Google is your friend.
 
  • #3
Not that your suggestion is wrong, but when looking in my book, it says "use the speed of sound in air at 20 degrees C, 343 m/s, unless otherwise specified."

So I guess I use that. But where does that help?
 
  • #4
The velocity of C=lambda*f. You are given both above--so what is C. It is not 343. Still do a google, meanwhile do you think the speed of sound increases or decreses with temp?

EDIT: I'll spare you the math as its been a long day: here is a table: http://www.sengpielaudio.com/calculator-speedsound.htm
 
  • #5
When I Googled it, the first thing that popped up was "speed of sound is 340.29."

And then if I multiply:

500 Hz * .68 m, I get 340. How does that connect?
 
  • #6
Dark Visitor said:
When I Googled it, the first thing that popped up was "speed of sound is 340.29."

And then if I multiply:

500 Hz * .68 m, I get 340. How does that connect?

Go back to my earlier post, I edited it, and remember google is your friend. There are lots of time when animations and what not can make a difficult concept clear. Books cannot do this!
 
  • #7
Thanks for the link, but what do I type in? I don't know a temperature.
 
  • #8
Find the temperature that corresponds to 340m/s and compare with your answer choices. Scroll down to the bottom of the page and find TABLE--I see your confusion.
 
  • #9
Okay. I did that, and 15 degrees C is the closest (it was 340.27). But how would I show my work for that? Unfortunately, my teacher would not accept "I used Google to get my answer" as an acceptable excuse. :rolleyes:
 
  • #10
Dark Visitor said:
Okay. I did that, and 15 degrees C is the closest (it was 340.27). But how would I show my work for that? Unfortunately, my teacher would not accept "I used Google to get my answer" as an acceptable excuse. :rolleyes:

Well, then look up the math. I don't know what you're using for a book or your notes, but there are several formula of increasing complexity that allow you to calculate C as a function of T. If your book says use 343, I'm assuming there is no discussion in it re variability. Wiki has a decent discussion with two fairly simple equations uou can solve in a couple of minutes.
 
  • #11
I don't see any way to show any math, so I just put a note on the side saying (343 is the speed of sound in 20 degrees C).
 
  • #12
As i said, its on wikipedia, or any of a 1000 other sites. But your call.BTW look at wiki under practical formulas for dry air.

C=331+0.6*c where c=temp in degrees c. Plug in 340 and you'll get 15 degrees c!
 
  • #13
I know, but I don't know which one to use, or how to use it. I'll keep looking. Can you finish helping me on "Find The Wavelength" please? It doesn't have to be tonight, but I need all my posts done by tomorrow and I have 3 left, including that one. Or help me on any others (the other 2 are "Kinetic Energy at the Bottom" and I am going to post another one in a second.) Thanks so much.
 
  • #14
look at the formula above on my last post. That is very simple.
 

Related to Help Needed: Wave Frequency & Wavelength vs. Air Temp

What is the relationship between wave frequency and air temperature?

The relationship between wave frequency and air temperature is an inverse one. As air temperature increases, the frequency of a wave decreases, and vice versa. This is because warmer air molecules have more energy and therefore vibrate more rapidly, leading to a higher frequency wave. On the other hand, colder air molecules have less energy and vibrate more slowly, resulting in a lower frequency wave.

How does air temperature affect the wavelength of a wave?

The wavelength of a wave is directly proportional to the air temperature. This means that as air temperature increases, the wavelength of a wave also increases, and as air temperature decreases, the wavelength decreases. This is because the speed of a wave is dependent on the medium through which it travels, and warmer air provides less resistance to the wave, allowing it to travel further and resulting in a longer wavelength.

What is the impact of air temperature on the speed of a wave?

The speed of a wave is directly affected by air temperature. As air temperature increases, the speed of a wave also increases, and as air temperature decreases, the speed decreases. This is because the molecules in warmer air are moving faster, allowing the wave to travel more quickly, while colder air molecules move more slowly, impeding the wave's speed.

How does the frequency of sound waves change with air temperature?

The frequency of sound waves also follows an inverse relationship with air temperature. As the air temperature increases, the frequency of sound waves decreases, and as the air temperature decreases, the frequency increases. This is because sound waves are a type of mechanical wave that require a medium to travel through, and changes in the medium (in this case, air temperature) can affect the speed and frequency of the wave.

What are some real-world applications of understanding the relationship between wave frequency, wavelength, and air temperature?

Understanding the relationship between wave frequency, wavelength, and air temperature is crucial in various fields, such as meteorology, acoustics, and telecommunications. In meteorology, this knowledge is used to predict weather patterns and analyze atmospheric conditions. In acoustics, it helps in the design and optimization of sound systems. In telecommunications, it is essential for the transmission and reception of signals. Additionally, this understanding also plays a role in areas such as aviation, seismology, and oceanography.

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