1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simple Harmonc Motion

  1. Oct 18, 2005 #1
    the question is
    An object is undergoing simple harmonic motion with period T_1 and amplitude A. At t = 0 the object is at x = 0. How far is the object from the equilibrium position at time t?

    well i come up with:
    A*cos((2*pi/T_1)*t)

    but i get that theres something wrong with my trigonometry, i cant figure out what im doing wrong
     
  2. jcsd
  3. Oct 18, 2005 #2

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Hint: if you substitute t=0, do you get x=0 with that cosine function?

    Zz.
     
    Last edited by a moderator: May 19, 2013
  4. Oct 18, 2005 #3
    Well as the object is at the equilibrium position at t = 0 there's no phase shift and the displacement is modelled as x = Asin(wt)

    The period (let's just call it T for now) = 2pi/w, therefore w = 2pi/T

    The equation for the displacement at time t then comes to x = Asin(2*pi*t/T), so unless I'm mistaken you just misread the initial conditions (if you wanted to make it into a cos expression you could give it a phase shift of pi/2).

    Cheers,
    Just some guy
     
  5. Oct 18, 2005 #4
    OMG thanks so much, i noticed the mistake, hehe, its pretty late, should be sleeping not prepping for my upcoming middies..
    Thanks guys for quick replies!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?