Answer:
When they are approaching each other
[tex]f_a = 2228.7 \ Hz[/tex]
When they are passing each other
[tex]f_a = 2100Hz[/tex]
When they are retreating from each other
[tex]f_a = 1980.7 Hz[/tex]
Explanation:
From the question we are told that
The velocity of car one is [tex]v_1 = 13.0 m/s[/tex]
The velocity of car two is [tex]v_2 = 7.22 m/s[/tex]
The frequency of sound from car one is [tex]f_e = 2.10 kHz[/tex]
Generally the speed of sound at normal temperature is [tex]v = 343 m/s[/tex]
Now as the cars move relative to each other doppler effect is created and this can be represented mathematically as
[tex]f_a = f_o [\frac{v \pm v_o}{v \pm v_s} ][/tex]
Where [tex]v_s[/tex] is the velocity of the source of sound
[tex]v_o[/tex] is the velocity of the observer of the sound
[tex]f_o[/tex] is the actual frequence
[tex]f_a[/tex] is the apparent frequency
Considering the case when they are approaching each other
[tex]f_a = f_o [\frac{v + v_o}{v - v_s} ][/tex]
[tex]v_o = v_2[/tex]
[tex]v_s = v_1[/tex]
[tex]f_o = f_e[/tex]
Substituting value
[tex]f_a = 2100 [\frac{343 + 7.22}{ 343 - 13} ][/tex]
[tex]f_a = 2228.7 \ Hz[/tex]
Considering the case when they are passing each other
At that instant
[tex]v_o = v_s = 0m/s[/tex]
[tex]f_o = f_e[/tex]
[tex]f_a = f_o [\frac{v }{v } ][/tex]
[tex]f_a = f_o[/tex]
Substituting value
[tex]f_a = 2100Hz[/tex]
Considering the case when they are retreating from each other
[tex]f_a = f_o [\frac{v - v_o}{v + v_s} ][/tex]
[tex]v_o = v_2[/tex]
[tex]v_s = v_1[/tex]
[tex]f_o = f_e[/tex]
Substituting value
[tex]f_a = 2100 [\frac{343 - 7.22}{343 + 13} ][/tex]
[tex]f_a = 1980.7 Hz[/tex]
