Waves and relativistic doppler effect?

Question

Hello everyone.

I am not very sure of this proof for my homework. If someone can help me I would be very happy.

-Police radar detects the speed of a car. Microwaves of a precisely known frequency are broadcast toward the car. The moving car reflects the microwaves with a Doppler shift. The reflected waves are recieved and combined with an attenuated version of the transmitted wave. Beats occur between the two microwave signals. The beat frequency is measured.
For an electromagnetic wave reflected back to its source fomr a mirror approaching at speed v, show that the reflected wave has a frequency:
f = fsource * (c+v) / (c-v)

O_O

Answer 1

Relativistic motion implies motion of masses moving at the speed of light.
If the motion of the source is equal zero V=0
The resultant frequency is equal to Fsource . If V approaches C ,the Resultant frequency approaches infinity.
The difference betwen the resutant frequency and the source frequency is the beat frequency.