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: Why backward travelling wave?

  1. Jul 17, 2006 #1
    I have a wave eqn that is of the standard form (y=sin(kx-wt)) and have a positive constant velocity. But when I graph it, it appears to be moving backwards with a greater t producing a lesser x for each specific y. How can this be?

    The eqn is y=10sin(18.35x-6283t)
  2. jcsd
  3. Jul 17, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    It could be a reflected wave.

    The wave direction is either + or - with respect to the coordinate system. In one dimension, waves can move in one of two directions - forwards or backwards.
  4. Jul 17, 2006 #3
    How can it be a reflected wave when there is nothing to reflect it with? The time I subed in was tiny and it still showed a backward moving wave. So the wave is going backwards immediately after t=0.
  5. Jul 17, 2006 #4
    I know where I made my mistake. I didn't fully understand how the phase component worked. The wave turns our to be a forward travelling wave after all.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook