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: Displacement of a Wave

  1. Apr 9, 2008 #1
    1. The problem statement, all variables and given/known data

    The displacement of a wave traveling in the positive x-direction is [tex]D(x,t) = (3.5cm)sin(2.7x - 124t)[/tex], where x is in m and t is in s.

    What are the frequency, wavelength, and speed?

    2. Relevant equations



    3. The attempt at a solution

    Not sure where to start. Can someone point me in the right direction?
     
  2. jcsd
  3. Apr 9, 2008 #2

    Kurdt

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

  4. Apr 9, 2008 #3
    so what you're saying is that [tex]D(x,t) = (3.5cm)sin(2.7x - 124t) =Asin(kx - \omega t)[/tex]

    If that's true than A = 3.5cm = 0.035m. k = 2.7 and [tex]\omega = 124[/tex]

    and I know that
    [tex]v = \frac{\omega}{k} = \frac{124}{2.7} = 46m/s[/tex]

    and

    [tex] \lambda = \frac{2 \pi}{k} = \frac{2 \pi}{2.7} = 2.33m[/tex]

    [tex]v= f \lambda \Rightarrow f = \frac{v}{\lambda} = \frac{46}{2.33} = 14.7Hz[/tex]
     
    Last edited: Apr 9, 2008
  5. Apr 9, 2008 #4

    Kurdt

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Yes from a glance that looks ok.
     
  6. Apr 9, 2008 #5
    Check your calculation of frequency.
     
  7. Apr 9, 2008 #6

    Kurdt

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Ahh yes, but I presume that was just a typo on the posters part.
     
  8. Apr 9, 2008 #7
    Thanks, it should be 19.7Hz.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook