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Centripetal Force question

  1. Jun 12, 2009 #1
    "A 0.400-kg pendulum bob passes through the lowest part of its path at a speed of 3.00 m/s.
    What is the tension in the pendulum cable at this point of the pendulum is .8 meters long?"

    I would like to ask for some help on understanding centripetal force in this particular situation. I realize gravity is pulling down on the bob, while tension is counteracting gravity, and centripetal force is also counteracting gravity.

    I would like someone to explain to me why the sum of the forces here is the total centripetal force, or Tension minus force of gravity.
  2. jcsd
  3. Jun 12, 2009 #2

    Doc Al

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    Staff: Mentor

    It sounds like you are thinking of centripetal force as if it were a third force on the bob. It's not. The only forces acting on the bob are tension and gravity. "Centripetal force" is just a name for the radial component of the net force.
  4. Jun 12, 2009 #3
    thank you very much, that's why i was so confused. Centripetal force is just another name for net force, but in angular motion!
  5. Jun 12, 2009 #4


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    Homework Helper

    For the radial component, yes. You could have a tangential component of force too, but it's not centripetal.
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