Answer:
The police car is moving at 41.24 m/s.
Explanation:
To find the speed of the police car we need to use the Doppler equation:
[tex] f = f_{0}(\frac{v + v_{r}}{v + v_{s}}) [/tex]
Where:
v: is the speed of the sound = 343 m/s
[tex]v_{r}[/tex]: is the speed of the receiver = 12 m/s
[tex]v_{s}[/tex]: is the speed of the source =?
f: is the observed frequency = 959 Hz
f₀: is the emitted frequency = 1038 Hz
Both terms are positive in the fraction because the velocity of the sound is in the opposite direction to both velocities of the police car and the other car.
By solving the above equation for [tex]v_{s}[/tex] we have:
[tex] v_{s} = \frac{f_{0}(v + v_{r})}{f} - v = \frac{1038(343 + 12)}{959} - 343 = 41.24 m/s [/tex]
Therefore, the police car is moving at 41.24 m/s.
I hope it helps you!
