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: Standing waves and harmonic waves

  1. Apr 26, 2008 #1
    [SOLVED] standing waves

    1. The problem statement, all variables and given/known data

    A standing wave is a superposition of two harmonic waves described by
    y1= Asin(kx+wt) and
    y2= A sin(kx-wt),

    where A=3.31594 cm, k=10.0531 m-1, and w=18.2212 s-1.

    Determine the smallest positive value of x correspoding to a node.

    So i added the two waves together and got y=2Asin(kx)cos(wt). I set y=0 and tried solving for x but i just got zero which was incorrect. Can someone help me solve these types of problems. Thanks.
     
  2. jcsd
  3. Apr 26, 2008 #2

    olgranpappy

    User Avatar
    Homework Helper

    there are a lot of x values for which

    0=2Asin(kx)

    is true... x=0 is one of them.

    to find the other zeros you have to know the zeros of the sin function... i.e., 0,pi,2pi,3pi, etc

    so set kx equal to the smallest *nonzero* value listed above to find the node you want.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook