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## Homework Statement

A sound source emits sounds of frequency 210 Hz that travel through still air at 340 m/s. The listener moves at 85 m/s relative to still air toward the stationary source. What is the wavelength of the sound between the source and the listener?

## Homework Equations

f' = f[1+ Vlistener/Vsound]

v=(wavelength)f

## The Attempt at a Solution

well using the doppler effect since the listener is moving towards the stationary source i know it will be f'=f[1+Vlistener/Vsound]

i find the f' right... but when using v=wavelength*frequency, which frequency do i actually use. because i know although im solving for f' , im just wondering if its a trick or something because i'm a little confused on the concept.

so for f' i get 262.5 Hz

then i plug it in to the v=wavelength*freq , but which velocity do i use? the speed of sound or the speed of the listener moving?

using the speed of sound i get 340 m/s = wavelength * 262.5 and end up with 1.295m as the wavelength.