Physics (AS & A Level) · May / June 2026 · Paper 12 · Question 24
9702Doppler effect for sound waves
The siren on an emergency vehicle emits a sound of constant frequency 1100 Hz. The driver in a stationary car hears the sound at a frequency of 1000 Hz. The speed of sound in air is 340 m s⁻¹. What is the velocity of the emergency vehicle?
- A31 m s⁻¹ away from the stationary car
- B34 m s⁻¹ away from the stationary car
- C31 m s⁻¹ towards the stationary car
- D34 m s⁻¹ towards the stationary car
As printed in the paper
Show the answer
Correct answer: B. 34 m s⁻¹ away from the stationary car
Make a free account to save your answers and see your weak topics and ask the AI why a wrong answer is wrong.