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!

Finding combined amplitude of out of phase waves

  1. Aug 2, 2009 #1
    1. The problem statement, all variables and given/known data

    "Two waves are traveling in the same direction along a stretched string. The waves are 30.0° out of phase. Each wave has an amplitude of 4.00 cm. Find the amplitude of the resultant wave."

    2. Relevant equations

    y(x,t) = Asin(kx - [tex]\omega[/tex]t)

    3. The attempt at a solution

    Assuming that both waves are sinusoidal, I'm just summing up the two waves as follows:

    (4.00 cm)sin(kx-[tex]\omega[/tex]t) + (4.00 cm)sin(kx-[tex]\omega[/tex]t + 30)

    but I'm not sure how to find a numerical amplitude with this. Thanks for the help.
     
  2. jcsd
  3. Aug 2, 2009 #2

    kuruman

    User Avatar
    Homework Helper
    Gold Member

    Look up the trig identity for sina + sinb.
     
  4. Aug 2, 2009 #3
    And don't forget to use radians to measure the angle, just to make things a bit more consistent.
     
    Last edited: Aug 2, 2009
  5. Aug 2, 2009 #4
    So what do I do with the variables "kx-[tex]\omega[/tex]t"? They're not given in the problem.
     
  6. Aug 2, 2009 #5
    You are only asked about the amplitude of the resultant wave. The rest is irrelevant.
     
  7. Aug 2, 2009 #6
    Ok thanks
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook