1. Limited time only! Sign up for a free 30min personal 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 = Asin(wt + angle) and circular motion diagram?

  1. Nov 20, 2013 #1
    This is the type of diagram I'm talking about:

    http://www.google.co.uk/url?sa=i&rc...VBtPdh26viVXkWaWL6rTIk7w&ust=1385070490503327

    It's the image the image next to Quest 3T

    If x = Asin(wt) surely the x value is the length of the opposite side, not the displacement of the object in SHM?
    I understand if x = Acos(wt) but why is it always written x = Asin(wt)?!
    sin(wt) doesn't give that length along the horizontal axis?!!!
     
  2. jcsd
  3. Nov 20, 2013 #2
    I really don't understand what you're asking, your link didn't really work. Maybe you could explain your question better?



    The general solution to the SHM equation is ##x(t)= A\cos (\omega t+\phi) + B\sin (\omega t+\phi)##.

    The equations that link was using were from using a trig identity on the general solution. The idienty: ##\cos (C+D) = \cos (C)\cos (D) - \sin (C) \sin (D)##, if you plug in the right values, you end up with the desired equations.

    The key is that the phase constants will be different for the ##\sin## and ##\cos## versions. If you recall that ##\sin (\alpha + \frac{\pi}{2}) = \cos (\alpha )##, it's only a matter of "lining" them up to get an equivalent expression. All of the different versions of the SHM solution have constants that are related by fixed equations.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: X = Asin(wt + angle) and circular motion diagram?
  1. Optimum angle (Replies: 3)

  2. Mirrors at an angle (Replies: 1)

  3. Ax = x cos(angle) (Replies: 4)

Loading...