1. Not finding help here? Sign up for a free 30min 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!

Frequency of two objects moving toward eachother

  1. Apr 27, 2012 #1
    1. The problem statement, all variables and given/known data

    A motorcyclist and a police car are moving toward one another. The police car emits a sound with frequency of 502 Hz and has a speed of 27m/s. The motorcycle has a speed of 12 m/s.
    What frequency does the motorcyclist hear?

    2. Relevant equations

    f=1/T
    f'=f(1+v/vs)

    3. The attempt at a solution

    f'=502(1+27/12)
    This gave me f'=1631.5 but it says this is incorrect
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 27, 2012 #2
    I think your equations are wrong. According to the Doppler Effect, the apparent frequency ##n_a=(\frac{V+V_o}{V-V_s}) n##

    ## V ## is the velocity of sound.
     
  4. Apr 27, 2012 #3
    so it would be
    (27+343)/(12-343)*502
    f=-561.15
     
  5. Apr 27, 2012 #4
    read my post again.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook