A police car moving at a constant velocity with its siren on, passes a stationary listener.
The graph below shows the changes in the frequency of the sound of the siren detected by the listener.
6.1 State the Doppler Effect in words. (2)
6.2 Write down the frequency of the sound detected by the listener as the police car:
6.2.1 Approaches the listener (1)
6.2.2 Moves away from the listener (1)
6.3 Calculate the speed of the police car. Take the speed of sound in air to be 340 m∙s-1. (6)
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