Physics (AS & A Level) · Oct / Nov 2019 · Paper 11 · Question 24

The siren of a moving police car emits a sound wave with a frequency of 440 Hz. A stationary observer hears sound of frequency 494 Hz. The speed of sound in the air is 340 m s–1. What could be the speed and the direction of movement of the car?

1. A37 m s–1 directly towards the observer
2. B37 m s–1 directly away from the observer
3. C42 m s–1 directly towards the observer
4. D42 m s–1 directly away from the observer

As printed in the paper