Answer:
A) As the ambulance's siren moves toward a stationary hearer, the quality of sound will have a higher pitch
B) As the ambulance's siren moves away from a stationary hearer, the quality of sound will have a lower pitch.
Explanation:
From Doppler effect, the closer the source of sound gets to the observer, the higher the frequency and in turn the higher the pitch.
Meanwhile, the farther a source goes from an observer, the lower the frequency of the sound and also the lower the pitch.
Thus, as the ambulance's siren moves toward a stationary hearer, the quality of sound will have a higher pitch.
As the ambulance's siren moves away from a stationary hearer, the quality of sound will have a lower pitch.
Answer:
a. The quality of the sound would have a high pitch and thus be loud.
b. The quality of the sound would have a low pitch and thus would have a lower volume than the sound from the source.
Explanation:
Using the formula for Doppler shift f' = (v ± v')f/(v ± v") where v = speed of sound in air, v'= speed of hearer = 0 m/s (since he is stationary), v" = speed of ambulance and f = frequency of sound from ambulance
So, f' = (v ± v')f/(v ± v")
f' = (v ± 0)f/(v ± v")
f' = vf/(v ± v")
a. What is the quality of the sound of an ambulance's siren when it moves toward a stationary hearer?
Since the source (ambulance) moves towards the detector, (hearer), we would get an upwards shift in frequency. (Since our denominator has to be a minimum, so we use the minus sign for v"). So, the quality of the sound would have a high pitch and thus be loud.
b. What is the quality of the sound of an ambulance's siren when it moves away from a stationary hearer?
Since the source (ambulance) moves away the detector, (hearer), we would get a downward shift in frequency. (Since our denominator has to be a maximum, so we use the plus sign for v"). So, the quality of the sound would have a low pitch and thus would have a lower volume than the sound from the source.
