Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wavelengths introduction please

  1. Apr 17, 2010 #1
    1. The problem statement, all variables and given/known data

    So, I was wondering how I can correlate frequency, amplitude, wavelength, period, and time with each other. I'm trying to solve this problem. A 4.5 Hz wave with an amplitude of 12 cm and a wavelength of 27 cm travels along a stretched horizontal string. a) how far does a given peak on the wave travel in a time interval of 0.50 seconds? b)how far does a knot on the string travel in the same time interval?
    I just would like the basic conceptions explained so I can try to figure this problem out myself! Thanks.

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Apr 17, 2010 #2
    For the first part, you know that the velocity is given by the wavelength multiplied by the frequency. Once you have the velocity, you multiply it with the time interval to get the distance.

    I'm confused about what the question is referring to in the second part.
  4. Apr 17, 2010 #3
    Thanks for the help on the first part. The second part of the question was asking, "how far does a knot on the string travel in the same time interval?" Personally, I'm quite confused with the second part as well. Is it asking if there was a knot tied into the string?
  5. Apr 18, 2010 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    A knot represents a "fixed" point on the string. It will oscillate up and down, but not travel along the string. The amplitude and frequency determine how a knot would move.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook