# Finding the wavelength and frequency

1. Nov 25, 2009

### sonutulsiani

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

A sound source is moving at 80 m/s toward a stationary listener that is standing in still air. The source emits sound at a frequency of 200Hz. Assume that the sound travels at still air at 343 m/s.

1. The wavelength of the sound in the region between the source and the listener is

A. 2.12 m
B. 1.72 m
C. 1.32 m
D. 1.82 m

2. The frequency heard by the listener using the above wavelength is

A. 261 Hz
B. 320 Hz
C. 199 Hz
D. 162 Hz

A sound source is moving at 80 m/s from a stationary listener that is standing in still air. The source emits sound at frequency of 200 Hz that travels in still air at 343 m/s.

3. The wavelength of the sound in the region between the source and the listener is

A. 2.12 m
B. 1.72 m
C. 1.32 m
D. 1.82 m

4. The frequency heard by the listener

A. 260 Hz
B. 320 Hz
C. 199 Hz
D. 162 Hz

2. Relevant equations

3. The attempt at a solution

So the first one I got it as 343-80=263 m/s Then wavelength = velocity / frequency = 263/200 = 1.32

2. Frequency = velocity/wavelength = 343/1.32 = 261 HZ

3. 343+80=423 m/s wavelength= 423/200 = 2.12

4. Frequency = 343/2.12 = 162 Hz

Are these correct?