Physics (AS & A Level) · May / June 2017 · Paper 11 · Question 25

A car travelling in a straight line at a speed of 30 m s⁻¹ passes near a stationary observer while sounding its horn. The true frequency of sound from the horn is 400 Hz. The speed of sound in air is 336 m s⁻¹. What is the change in the frequency of the sound heard by the observer as the car passes?

1. A39 Hz
2. B66 Hz
3. C72 Hz
4. D78 Hz

As printed in the paper