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: A begginners question on S.H.M

  1. May 23, 2004 #1
    Hello,
    this is my first post on this forum and it is about simple harmonic motion. I can't seem to understand why the displacement x has two functions. What I mean is, x(t)=A.Sin(wt+phi) is the solution of differential equation of s.h.m; which is used by our physics teacher to derive the velocity and acceleration of a particle performing s.h.m; BUT in many text books I found that x(t)=A.Cos(wt+phi) ... my question is how can there be two values for x ?

    Any help would be very helpfull,
    Thank You.
    Rohit Arondekar.
     
  2. jcsd
  3. May 23, 2004 #2

    arildno

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    Dearly Missed

    Both versions are perfectly acceptable, as long as you remember that the "phi" in the sine representation will differ from the "phi" in the cosine representation, since we have, in general:
    [tex]\cos(\theta-\frac{\pi}{2})=\sin(\theta)[/tex]
     
  4. May 24, 2004 #3
    Yay! cheers arildno :)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook