4 concepts
Moving Observer
The Doppler effect is the apparent change in frequency of a wave when the observer and the source of the wave move relative to each other.
Moving Source
The Doppler effect is the apparent change in frequency of a wave when the observer and the source of the wave move relative to each other.
General Case
The Doppler effect is the apparent change in frequency of a wave when the observer and the source of the wave move relative to each other.
Sonic Booms
A sonic boom is the sound associated with the shock waves created by an object traveling through the air faster than the speed of sound.