Question 6

A car moves at a constant speed of 10 m∙s^-1 TOWARDS a stationary sound source.
The sound source emits sound waves of frequency 880 Hz.
A sound detector A is attached to the car and another sound detector B is attached to the sound source. Detector B detects the sound waves reflected from the car. The speed of sound in air is 340 m∙s^-1.

6.1 State the Doppler effect in words. (2)

6.2 Calculate the wavelength of the sound waves emitted by the source. (3)

6.3 Calculate the frequency of the sound waves detected by detector A. (4)
The sketch graph below shows the frequency recorded by detector A.

6.4 Redraw the graph above for detector A in your ANSWER BOOK. On the same set of axes, sketch the graph of the frequency recorded by detector B.
Label this graph as B. (2)
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