Physics (AS & A Level) · Oct / Nov 2023 · Paper 13 · Question 22

A loudspeaker emits sound of frequency f_s. The loudspeaker is attached to a car that moves with increasing speed directly towards a stationary observer. Which statement describes the frequency of the sound heard by the observer?

1. Aa frequency greater than f_s and increasing
2. Ba frequency greater than f_s but decreasing
3. Ca frequency less than f_s and decreasing
4. Da frequency less than f_s but increasing

As printed in the paper