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Homework Statement
You are in charge of calibrating the radar guns for a local police department. One such device emits microwaves at a frequency of 2.15 GHz. During the trials, these waves are reflected from a car moving directly away from the stationary emitter. You detect a frequency difference (between the received microwaves and the ones sent out) of 291 Hz. Find the speed of the car and give the answer in km/h.
Homework Equations
The Attempt at a Solution
One thing that I kind of don't understand, is that the radar gun is both the emitter and receiver, and the guy is stationary. So I just assumed that you would treat the car as the receiver. I even attempted to treat the car as the emitter and the guy as the receiver thinking of after the microwaves hit the car, but that gave the same answer.
(2.15 * 10^9 ) - 291 = ( (343 - v)/(343) ) * (2.15 * 10^9 )
v = 4.6425 * 10^-5 m/s
v * 3.6 = 1.6 * 10^-4 km/h