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!

Beat Frequency/Truck Speed!

  1. Sep 12, 2006 #1
    Two loudspeakers emit 300 Hz notes. One speaker sits on the ground. The other speaker is in the back of a pickup truck. You hear 9.00 beats per second as the truck drives away from you.


    Alright, I'm assuming this problem has to deal with doppler shifts + beat frequency.

    The observer is stationary (the guy) as the source moves away. Therefore am I to believe that F_observer = F_source * (v_w / v_w + v_s) where v_w is 343m/s, F_source = 300 Hz,

    Now for beat frequency, I know that is F_beat = F_1 - F_2 = 9 beats/sec -- so does that mean

    F_observer = 291 Hz?? I'm not sure because 300Mhz - 9 = 291?

    I am almost 80% sure I'm wrong, but this feels like a doppler shift question to me. Am I on the right track, at least?

    Thanks all

    Btw, how do I input LaTex commands in here? Do I type the code?

  2. jcsd
  3. Sep 13, 2006 #2
    I need help, I still can't figure this out! Anyone?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Beat Frequency Truck Date
Beat frequency question Sep 27, 2017
How do you find speed given the beat frequency? Aug 4, 2017
Beat problem Jul 4, 2017
How much of the reflected sound is heard by person A? Jun 12, 2017
Flute player initial frequency? May 14, 2017