Physics (AS & A Level) · Oct / Nov 2017 · Paper 13 · Question 26

A car travelling at a steady speed in a straight line passes close to a stationary observer. The observer measures the frequency of the sound from the engine. As the car approaches, the observed frequency is 220 Hz. When the car moves away, the observed frequency is 180 Hz. The speed of sound in air is 340 m s–1. What is the speed of the car?

1. A8.5 m s–1
2. B31 m s–1
3. C34 m s–1
4. D38 m s–1

As printed in the paper