# Speed of Sound in water given frequency

1. Jul 26, 2009

### jdg

A 190 Hz sound traveling in fresh water has speed of?

I'm not sure which equations to use, or where to start. I tried wavelength = V/f , with V being constant, 1493 m/s

Any help would be greatly appreciated!!

Last edited: Jul 26, 2009
2. Jul 26, 2009

### jgens

Are you trying to find the speed or the wavelength in this problem (the question indicates speed while your work indicates wavelength)? If the question is about speed, what do you know about the speed of a wave through a particular medium? If the question is about wavelength, what is the relationship between the frequency, wavelength, and speed of a wave?

3. Jul 26, 2009

### jdg

I know it has something to do with the density of the medium, but i'm not sure what the equation is

-the density of fresh water is 1000 kg/m3

4. Jul 26, 2009

### jgens

I'm guessing the question is about the speed of the wave then? Well, just to get you thinking, in air at a constant temperature, what is the difference in speed (if any) between a sound wave with a frequency of 200 Hz and a sound wave with a frequency of 400 Hz?

5. Jul 26, 2009

### jdg

I would think that at a constant temperature the speed would be constant?

6. Jul 26, 2009

### jgens

Correct! So what does this suggest about the pertinence of the frequecy of the wave in this problem?

7. Jul 26, 2009

### jdg

the frequency wont change the speed in water?

8. Jul 26, 2009

### jgens

No, it suggests that the speed of the wave doesn't depend on the frequency!

9. Jul 26, 2009

### jdg

so it doesn't matter what the frequency is, the speed of sound remains the same in the water?

10. Jul 26, 2009

### jgens

Yup, assuming that the water is at a constant temperature.

11. Jul 26, 2009

### jdg

so how do I find that speed with the given information?

12. Jul 26, 2009

### jgens

Well, you've already provided a speed of sound in water (you did in the first post)!

13. Jul 26, 2009

### Feldoh

Google it. Since you all ready said that the frequency doesn't have anything to do with the actual speed.

14. Jul 26, 2009

### HallsofIvy

Staff Emeritus
You said, in your first post: "wavelength = V/f , with V being constant, 1493 m/s".

If you were trying to find the wavelength, given the frequency, you could use that formula. But you said you were trying to find the speed of sound in water which, as you said, is 1493 m/s!

15. Jul 26, 2009

### jdg

I used the constant, 1493 m/s, which is given in my text for SoS in fresh water, it came out wrong

16. Jul 26, 2009

### JazzFusion

Were you given a value for the bulk modulus of water?