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Homework Help: Wave, finding the velocity of the incoming car.

  1. Apr 28, 2016 #1
    1. The problem statement, all variables and given/known data

    The highway police, stationary hidden behind the barrier, shoot a radio wave that got a frequency of 8 GHZ, from his radar gun to measured the velocity of the incoming car, that's coming toward him. After the radio wave hit the car and reflect back, the police found that the total frequency is increase by 2100HZ. If the velocity of the radio wave in the air is 3x10^8 m/s, what's the speed of the incoming car?

    2. Relevant equations

    3. The attempt at a solution

    I've tried to solve this question by combining the V= F x ramda, and V = S/T equation, but it doesn't give the correct answer. I'd also use the equation F=CF/2F, but again it doesn't thrive me the correct answer.
  2. jcsd
  3. Apr 28, 2016 #2


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    Staff: Mentor

    Hi Physicsman567, Welcome to Physics Forums.

    For your problem you should research "Doppler effect" and "Doppler effect police radar" to find relevant equations.
  4. May 2, 2016 #3
    I solved it!
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