Answer:
When they are approaching each other
When they are passing each other
When they are retreating from each other
Explanation:
From the question we are told that
The velocity of car one is
The velocity of car two is
The frequency of sound from car one is
Generally the speed of sound at normal temperature is
Now as the cars move relative to each other doppler effect is created and this can be represented mathematically as
Where is the velocity of the source of sound
is the velocity of the observer of the sound
is the actual frequence
is the apparent frequency
Considering the case when they are approaching each other
Substituting value
Considering the case when they are passing each other
At that instant
Substituting value
Considering the case when they are retreating from each other
Substituting value