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Homework Help: Circular Motion probem - 3

  1. Sep 3, 2013 #1
    The problem is as such :


    Attempt to the problem:


    The answer is confusing Option D

    Thank you all in advance.
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. Sep 3, 2013 #2


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    Tension is a force and force is related to acceleration via Newton's 2nd law. How do you determine the acceleration of a particle moving in a circle at constant angular speed ##\omega##?

    Draw free-body diagrams for each mass. You need to consider the NET force acting on each particle.
  4. Sep 4, 2013 #3
    But friend how could it be done without knowing the separations.

    If we draw the free body diagram there would be two accelerations - tangential aT and centripetal aR

    aR will be along the thread and it will equate the tension. Isn't it?
  5. Sep 4, 2013 #4
    Last edited by a moderator: May 6, 2017
  6. Sep 4, 2013 #5
    Since the only forces acting on the particles are tensions which are radial ,there will be no tangential acceleration.

    The FBD in the above post#4 is incorrect.

    Let the tension in the string OA be T1,AB be T2 and BC be T3.The length of each string segment be l.

    Now for A, T1-T2=mv12/l

    For B ,T2-T3=mv22/2l

    Similarly you can write eq for C.

    From this you will get the desired ratio.
  7. Sep 4, 2013 #6
    Thank you very much friends. I got the answer. Problem has been cleared.
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