# Homework Help: : waves

1. Jan 23, 2009

### I_LuV_FiZiX

1. The problem statement, all variables and given/known data
A string from an Andrew Kirk violin is 30.0 cm long, with a linear density of 0.645 g/m. The violin is placed near a loudspeaker that is fed by an audio oscillator of variable frequency. It is found that the string is set into oscillation only at the frequencies 1312 Hz and 1749 Hz, as the frequency of the oscillator is varied over the range 1093 Hz to 1968 Hz. What is the tension in the string?

2. Relevant equations
v=sqrt(T/linear density) v=lambda x frequency

3. The attempt at a solution
I made these 2 equations equal to each other. However, I am unsure as to what proportion of L lambda is, and what to use for frequency. Once I know what to do here I can then isolate for tension and solve.

Thanks in advance, any help would be GREATLY appreciated.

2. Jan 23, 2009

### Kurdt

Staff Emeritus
3. Jan 23, 2009

### I_LuV_FiZiX

can you give me a further hint as to how to find what to use for frequency? Ive got less than an hour :S

4. Jan 23, 2009

### Kurdt

Staff Emeritus
The frequencies given will be integer multiples of a fundamental frequency. So 1312Hz will be $nf_1$ for example and 1749Hz will be the next integer multple from that, so it'll be $(n+1)f_1$.

5. Jan 23, 2009

### I_LuV_FiZiX

oh okay...so is a final answer of correct? 2.77N I have one try left :S:S:S:S

6. Jan 23, 2009

### rl.bhat

Since length of the string remains the same, for different frequencies the number of loops must be different.
Hence 1312*(n+1) = 1749*n. Solve for n and then find tension.