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Homework Help: Oscillation problem, help!

  1. Apr 10, 2012 #1
    1. The problem statement, all variables and given/known data
    Hi! My question is about oscillation. The multiple choice answers and question is included in the picture attached! I also happen to know the answer is A by looking at the marscheme.

    3. The attempt at a solution
    I would've thought that since the ball is said to be held "stationary" in that position the forces would all have to be equal. Thus i would've thought C was the correct answer. If they had said that it's an oscillation where the ball is in position P and not mentioned it being held stationary, I would've answered A, however, knowing that the forces would've had to be unbalanced and acting towards the equilbrium point. Could anybody explain exactly why it's A? and not C? I think my problem is probably largely due to interpretation of the question. Thankyou for any replies!

    Attached Files:

  2. jcsd
  3. Apr 10, 2012 #2


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    Staff: Mentor

    If the ball is stationary then the forces must sum to zero net force. If they were all equal, would the sum be zero? Remember, you're adding vectors here.
  4. Apr 10, 2012 #3
    Hi, magiclink!
    Is that IB Physics?
  5. Apr 10, 2012 #4
    Hey! I just looked at the question and gave it a good look again. Turns out that the vectors did add vectorally to equal zero. A bit of an optical illusion to me. Thanks anyways! Sorry for wasting your time! :)

    And yes, tis IB physics indeed. ;)
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