# Frequency of sound waves from vibrating wire

whatisreality

## Homework Statement

The wire has mass 250g and is tied down at both ends. It has a length of 12.50m and a fundamental frequency of 25.0 Hz. It has linear mass density.
Sound travels at 344m/s in air. Calculate the frequency of the sound waves produced when the wire vibrates at its fifth harmonic frequency.

v=f lambda

## The Attempt at a Solution

Just from drawing the wave, I think the wavelength of the vibration on the wire is 12.5/3.
From v=f lamda, since we know the fundamental frequency and its wavelength at this point (25m), the wire is moving at 625m/s. Which seems very fast.
My problem is, I have no idea how these relate to the longitudinal wave produced in air! Velocities aren't the same. Wavelengths are, I think...

Homework Helper
If the fundamental frequency is a given ...

whatisreality
If the fundamental frequency is a given ...
Well, I don't know what to do with the fundamental frequency? Am I missing something really obvious?
Is the frequency of the sound wave the same as the frequency of vibration of the wire?

Homework Helper
Definitely. Yes.

whatisreality
Definitely. Yes.
Oh. So then

625 = f* 12.5/3? And that frequency is the frequency of the sound wave. Well... that was quite silly. Thanks anyway :)