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Homework Help: Tarzan swings

  1. Sep 9, 2010 #1
    1. The problem statement, all variables and given/known data
    tarzan swings through the jungle on a wine.at the lowest point of his swing, is the tension in the vine greater than,less then, or equal to the gravitational force


    2. Relevant equations

    its a conceptual question..

    3. The attempt at a solution
    i say that the tension on the string is greater b/c.. the vine has to bring him up again..... not sure if im correct.... been a while since i delt with forces...

    if... the gravitational for is more then the vine breaks..

    if the gravitational for is equal to the tension the he comes to a halt
     
  2. jcsd
  3. Sep 9, 2010 #2
    anything wrong with my conclusion ?
     
  4. Sep 9, 2010 #3

    PhanthomJay

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    Yes, you're missing the concept of centripetal acceleration, which, for an object moving in a curved path, always acts inward toward the center of the curve (center of the circle in this case). What's the direction of the centripetal acceleartion at the bottom of the curve? What must be the direction of the net force at the bottom of the curve?
     
  5. Sep 9, 2010 #4
    the "centripetal acceleration" is up and there is a tangential acceleration..so the tension on the vine must be greater then the gravitational force.....no?...
     
  6. Sep 9, 2010 #5

    PhanthomJay

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    That's right, the tension is greater. But at the bottom of the curve, there is no force in the x direction, so what is the tangential acceleration at the bottom? (that's an extra credit question:wink:).
     
  7. Sep 9, 2010 #6
    no acceleration in the x-direction o:)
     
  8. Sep 9, 2010 #7
    thank you jay!
     
  9. Sep 9, 2010 #8

    PhanthomJay

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    You are welcome. Bear in mind that there is both centripetal and tangential acceleration elsewhere on the curve. At the bottom, only centripetal. Going to bed now, good night.:zzz:
     
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