Ambulance A travels at 20m/s toward a stationary pedestrian. Ambulance B is at rest, but a cyclist rides at 20m/s directly toward it. Both ambulances use identical sirens.
Which statement correctly describes the pitches heard?
a) The cyclist hears a higher pitch than the pedestrian.
b) Both listeners hear the same pitch, which is higher than the siren’s rest pitch.
c) The pedestrian hears a slightly higher pitch than the cyclist.
d) Both listeners hear the rest pitch because only the source’s motion alters frequency.