IB Physics C.5 Doppler Effect Questionbank

(b) Outline why this change in frequency occurs.

(c) Suggest what would be heard if the source were moving away from the observer instead.

(d) Describe one real-life situation in which this Doppler effect can be experienced.

A fire truck moves past an observer at constant speed. Why is the siren pitch higher as it approaches than as it recedes?

A high-speed train travels at a constant velocity toward a station platform where a stationary observer is standing. The train's whistle emits a sound of a constant frequency.

(a) In the context of the moving train, explain why the observer detects a shorter wavelength than the one emitted by the whistle.

(b) The following data were recorded for the sound produced by the train as it approached the station:

Calculate the speed of the train, $v_s$.

(c) Describe the change in the frequency detected by the observer at the instant the train passes them and begins to move away.