1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Doppler effect

  1. Jun 24, 2012 #1
    1. The problem statement, all variables and given/known data
    Man travels down the highway in his car whistling middle C
    A policeman has a defective radar gun but passed a physics course. He hears the
    pitch change from D(294 Hz) immediately above middle C(262Hz) to A#(233Hz) immediately below
    middle C as the car passes.
    a) How fast is Professor Zoom traveling?
    b) Should Professor Zoom get a ticket? if speed limit is 100km/hr

    2. Relevant equations
    f = frequency of source
    f1 = frequency at observer
    c = speed of sound (330m/s)
    v = velocity of observer
    v1 = velocity of source

    source moving towards stationary observer.
    f x c/(c-v1) = f1

    source moving away from stationary observer.
    f x c/(c + v1) = f1

    3. The attempt at a solution
    So for source moving towards stationary observer

    f x c/(c-v1) = f1


    source moving away from stationary observer.
    f x c/(c + v1) = f1


    I just want to know if im on the right track, or what am I doing wrong? and do i add those two velocity together? when you convert those velocities into km/h they surpass 100km/hr so I said that yes he does get a ticket. Help please :) im a little lost...
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted