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Oscillating in Simple Harmonic Motion?

  1. Apr 24, 2012 #1
    1. The problem statement, all variables and given/known data
    A 200-g object is oscillating in simple harmonic monition with an amplitude of 2 cm and a period of 0.4 seconds. Find the velocity when its displacement from the equilibrium position is 0.5 cm.


    2. Relevant equations
    Restoring Force = -(constant force)(displacement)
    Elastic PE = 1/2 k(s squared)
    velocity = [itex]\sqrt{k/m(A squared - s squared}[/itex]


    3. The attempt at a solution
    I just need help finding the constant force. If I can figure out how to solve that variable, I can finish the problem just fine.
     
  2. jcsd
  3. Apr 24, 2012 #2

    gneill

    User Avatar

    Staff: Mentor

    I think you mean the "force constant", k, for the spring. Why not consider the formula for the period of a mass-spring system?

    Also try using the x2 and x2 icons in the edit frame header to produce superscripts and subscripts :wink:
     
  4. Apr 24, 2012 #3
    I missed them too.
    Hope they are repositioned at Quick Symbols and adding new symbol, 1/2.

    Thank you.
     
  5. Apr 24, 2012 #4
    Thanks, I'm not sure how I missed that - I think the first part of this homework fried my brain before I got to this and I just forgot to look at my other equations! However, when I acquired a k value of 49.35 and did the equation in my original post for velocity, I acquired a negative number under the radical, therefore giving me a non-real answer. Am I doing something wrong?
     
  6. Apr 24, 2012 #5

    gneill

    User Avatar

    Staff: Mentor

    Your value for k looks fine (you should include units when you present a number).

    The equation you wrote for velocity is okay. Maybe finger problems on the calculator? :smile:
    Why not show your calculation step by step?
     
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