# Homework Help: Frequency and length

1. Apr 13, 2010

### Brittykitty

. If the speed of sound in air is 343 m/s and the frequency of the tuning fork is 225 Hz, what is the length of the air column shown in the diagram?

wavelength= v ÷ f
wavelength =343[m/s] ÷ 225[Hz]
wavelength =1.52 m

I'm not feeling this is right, what am I doing wrong? Is length and wavelength two completely different things?

2. Apr 13, 2010

### AtticusFinch

Well we need the diagram. Sometimes the length will be the same as the wavelength sometimes the length will be different. It depends on what harmonic the tube resonates at.

3. Apr 13, 2010

### Brittykitty

I uploaded it to facebook the picture of the tuning fork lol :)

Last edited by a moderator: May 4, 2017
4. Apr 13, 2010

### Brittykitty

The diagram shows a tuning fork vibrating over an air column closed at one end by water. The length of the air column can be varied and is one quarter of the wavelength of the longest standing waves set up by the tuning fork.

and thats the other information about it

5. Apr 13, 2010

### flyers

The wavelength is right but don't forget that the length of an open-closed air column is not equal to the wavelength but rather only a quarter of it.

6. Apr 13, 2010

### AtticusFinch

Yes this is correct. You got the correct wavelength but there is only a quarter of a wavelength in the tube so find the appropriate length.

7. Apr 15, 2010

### Brittykitty

Thank you! so would I divide it by half?

8. Apr 15, 2010

### AtticusFinch

Almost. It says the longest wavelengths (fundamental harmonic) are 4 times the length of the tube.

So to find the length of the tube you would divide by 4, not 2.

9. Apr 16, 2010

### Brittykitty

thank you so much :):) I meant 4, I'm not sure why I put 2 lol