Question

a girl moves away from a source of sound at a constant speed. compared to the frequency of the sound wave produced by the source, the frequency of the sound wave heard by the girl is ___.
a higher
b the same
c cant be known
d lower

Explanation:

This problem is related to the Doppler effect. When the observer (the girl) moves away from the source of sound, according to the Doppler effect formula for sound \(f'=\frac{v - v_{o}}{v}f\) (where \(v\) is the speed of sound in the medium, \(v_{o}\) is the speed of the observer moving away from the source, and \(f\) is the frequency of the source). Since \(v - v_{o}

Answer:

d. Lower