Question text
22 A vehicle emits sound of a constant frequency. A stationary observer hears the sound. The vehicle moves directly towards the observer at constant speed. The observer hears sound of frequency f . o The vehicle then accelerates, still moving towards the observer, travels at a higher steady speed for a time and then decelerates until it stops. What is the variation in the frequency of the sound that is heard by the observer? A The observed frequency will fall, then remain steady then return to the frequency f . o B The observed frequency will fall, then remain steady then rise to a higher frequency than f . o C The observed frequency will rise, then remain steady then fall to a lower frequency than f . o D The observed frequency will rise, then remain steady then return to the frequency f . o
22 A vehicle emits sound of a constant frequency. A stationary observer hears the sound.
The vehicle moves directly towards the observer at constant speed. The observer hears sound of
frequency f .
o
The vehicle then accelerates, still moving towards the observer, travels at a higher steady speed
for a time and then decelerates until it stops.
What is the variation in the frequency of the sound that is heard by the observer?
A The observed frequency will fall, then remain steady then return to the frequency f .
o
B The observed frequency will fall, then remain steady then rise to a higher frequency than f .
o
C The observed frequency will rise, then remain steady then fall to a lower frequency than f .
o
D The observed frequency will rise, then remain steady then return to the frequency f .
o
Select your answer: