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Tension of string of pendulum at lowest point

  1. Nov 5, 2007 #1
    I have tried the following question in direction of conservation of mechanical energy, but not sure how this related to the tension of string.

    A 2.5-kg object suspended from the ceiling by a string that has a length of 2.5 m is released from rest with the string 40 below the horizontal position. What is the tension in the string at the instant the object passes through its lowest position?

    How to solve this question?
    Last edited: Nov 5, 2007
  2. jcsd
  3. Nov 5, 2007 #2
    You're able to use the conservation of mechanical energy because zero work is done on the object by non-conservative forces. The only non-conservative force acting is the tension force, but it acts perpendicular to the path of the object at every instant, and so it does zero work.

    Does this help or are you still stuck?
  4. Nov 5, 2007 #3


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    Homework Helper

    the idea is to use conservation of energy to get the velocity at the bottom... then use centripetal acceleration ideas to get the force of tension...
  5. Nov 5, 2007 #4
    I see thanks for the help:)
    Ans is 42N.
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