IB Physics C.5 Doppler Effect Questionbank

A spacecraft, while receding from Earth at $0.85c$, emits light at a rest frequency of $5.00 \times 10^{14}\ \text{Hz}$. An Earth-based observer detects a redshifted signal. The frequency received on Earth is approximately $1.42 \times 10^{14}\ \text{Hz}$.

The diagram shows a stationary observer while a loudspeaker moves toward them, emitting a constant sound. The observer hears a change in the pitch of the sound due to the relative motion of the source.

A loudspeaker moves to the left at speed $\frac{v}{7}$, where $v$ is the speed of sound in air. It emits sound of frequency . A stationary observer is in front of the loudspeaker.

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.