Physics (AS & A Level) · May / June 2026 · Paper 14 · Question 23

A police car has a two-tone siren emitting sound of frequencies of 700 Hz and 1000 Hz. The police car is travelling at a speed of 40.0 m s⁻¹ towards a stationary observer. The speed of sound in the air is 340 m s⁻¹. What is the difference between the two frequencies of the sound that is heard by the observer?

1. A268 Hz
2. B300 Hz
3. C335 Hz
4. D340 Hz

As printed in the paper