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!

X= Acos(wt)? X= Asin(wt)?

  1. Oct 18, 2009 #1
    X= Acos(wt)?? X= Asin(wt)??

    1. The problem statement, all variables and given/known data

    X= Acos(wt)??

    X= Asin(wt)??

    Which is right? in some books, x = A sin(wt), while in other books, x= Acos(wt)...

    I'm confused.

    Please explain this to me. Thank you very much.
     
  2. jcsd
  3. Oct 18, 2009 #2

    rl.bhat

    User Avatar
    Homework Helper

    Re: X= Acos(wt)?? X= Asin(wt)??

    . f(x) is the projection of a particle moving in a uniform circular motion with radius A and angular velocity ω. If you take the projection on x-axis, then f(x) = Acosωt.
    Ιf you take the projection on y axis, then it is f(x) = Asinωt
     
  4. Oct 11, 2011 #3
    Re: X= Acos(wt)?? X= Asin(wt)??

    use x=Asin(wt) if the oscillation is starting from the equilibrium position (b/c if u look at a sin curve, it starts at a value of 0), and if it is starting at the amplitude, use x=Acos(wt). (b/c looking at a cosine curve, it starts at the amplitude)

    But since sin and cos are really the same functions except shifted over, these two equations are both true and essentially mean the same thing.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook