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Homework Help: Tension and Spring Forces

  1. Aug 15, 2008 #1
    I am a bit confused about such forces that act in a string or a spring. I am unable to guess their direction.
    Therefor I prepared myslf some examples through which i can understan the concpt of these forces.

    In diag1
    A force F is applied at end C. What will b the tensions at points A,B(mid point),C. Find their directions and their magnitues. (if the string has no mass)

    I can guess about tension at point A. Its going to pull the block of mass m. Therefore, tension will act away in the rightward direction. Am I right? What about the other points?
     

    Attached Files:

  2. jcsd
  3. Aug 15, 2008 #2
    Your attachment doesn't seem to be working. You shouldn't have to guess what direction the opposing force will be applied, it should be easy to realize. A spring will always want to return to its original position.

    The equation for this force is: F = -k*dx
     
  4. Aug 15, 2008 #3
    Last edited by a moderator: May 3, 2017
  5. Aug 15, 2008 #4
    A force F is applied at end C. What will b the tensions at points A,B(mid point),C. Find their directions and their magnitues. (if the string has no mass)

    I can guess about tension at point A. Its going to pull the block of mass m. Therefore, tension will act away in the rightward direction. Am I right? What about the other points?
     
    Last edited by a moderator: May 3, 2017
  6. Aug 15, 2008 #5

    tiny-tim

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    Hi ritwik06! :smile:

    A massless string (all strings in exam questions are massless :wink:) has the same tension all the way along. :smile:
     
  7. Aug 15, 2008 #6
    I wish to know their direction dear Tim. :smile:
     
  8. Aug 16, 2008 #7

    tiny-tim

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    … ah!

    ah … the tension acts in both directions.

    Tension is a pair of opposing forces on each tiny little bit of the string. :smile:

    (And if the string is massless, the two opposing forces are equal.)

    (same with compression)
     
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