# How to find wavelength with only distance

1. Mar 3, 2013

### PhizKid

1. The problem statement, all variables and given/known data

A metal rod attached to a tube with both closed ends is stimulated to create waves inside the tube.

If:
L = 1.0 m
d = 0.05 m
Speed of sound in air = 340 m/s
Speed of sound in metal = 1,000 m/s

Calculate the value of x using the wavelength of air.

2. Relevant equations
Frequency = Velocity / Wavelength

3. The attempt at a solution
The frequency of the the metal is the same as the frequency in air, so:

1,000 / (2*1.0) = 340 / wavelength of air

Because the wavelength of the metal is 2 * L.

340 / 500 = wavelength of air
0.68 = wavelength of air

How do I calculate wavelength with only the distance between two nodes (d)? I need x from wavelength according to the problem's instructions so I have to work backwards but I don't know any formulas for this one.

Last edited: Mar 3, 2013
2. Mar 3, 2013

### voko

Wavelength is the distance between two nearest nodes = d. Can you clarify what you are trying to find?

3. Mar 3, 2013

### PhizKid

I thought the wavelength was the distance between 3 nodes, since between two nodes is only half the cycle. This is where I'm confused...is the wavelength between two nodes, or is the wavelength between 3 successive nodes? Because I thought the distance between two nodes only completed half the cycle.

4. Mar 3, 2013

### voko

Sorry, you are right. What I meant to say was distance between two crests, which is what the diagram shows, I think.

5. Mar 3, 2013