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

Simple harmonic motion and amplitude of an object

  1. Jul 22, 2004 #1
    I have a short question:

    an object undergoes simple harmonic motion with a period T and amplitude A. How long does it take the object to travel from x = A to x = A/2 ?

    the answer is T/6, but im not sure how to get to that,

    Do I get it from x = Acos(2pi/T xt)?
    help :cry:
  2. jcsd
  3. Jul 22, 2004 #2


    User Avatar
    Science Advisor
    Gold Member

    You could (but I wouldn't use an x to stand for multiplication especially in an equation that already has an x in it). You could solve for t when x = A and when x = A/2 and find the difference in times.

    You know that x = A at t = 0.

    for x = A/2:

    [tex] x = \frac A 2 = A\cos \left( \frac{2\pi t}{T} \right ) [/tex]

    The cosine of 60 degrees is 1/2, so this reduces to:

    [tex] \frac \pi 3 = \frac{2\pi t}{T} [/tex]

    Solve for t and you'll find the answer.
  4. Jul 22, 2004 #3
    thanks so much :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook