# Homework Help: Fundamental frequency of oscillation in 2 ropes

1. Sep 24, 2015

### goonking

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

2. Relevant equations

3. The attempt at a solution
if the material are the same in both strings, then the density should be the same.
v = sqrt (tension/μ)

tension in the first string should be 30 kg x 9.8 m/s^2 = 294 N

next,

v = λƒ

and string#2 needs to have twice the frequency of string#1

and this is where I am stuck, don't know where to proceed from here

do I need wavelength here? if so, how would i find it?

2. Sep 24, 2015

### haruspex

You have two equations involving v, but you are not very interested in v. So what should you do with the two equations?
Next, you have the same equations for two different cases. Some of the variables are the same for both cases. It helps to clarify things if you create different symbols (like T1, T2) wherever the variables are different. That should produce two equations, neither involving v.

3. Sep 24, 2015

### goonking

do I equate them both? :

λƒ = sqrt (tension/μ) ???

also, what is interchangeable in each string with masses? do they both have the same wavelength? do they have the same velocity?

4. Sep 24, 2015

### haruspex

You know the tensions (different) and the wavelengths (different). You know the frequencies are different. What does that leave?

5. Sep 24, 2015

### goonking

velocity? but if tension is different then velocity should be different too, right?

6. Sep 25, 2015

### haruspex

We eliminated velocity. Look at your equation in post #3. The are four variables in there. Which one has not been mentioned?