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Homework Help: Lowering an object without breaking the the rope

  1. Oct 11, 2015 #1
    1. The problem statement, all variables and given/known data
    How could a 1000 N object be lowered from a roof using a cord whose breaking strength is only 800 N?

    2. Relevant equations
    ∑F=ma

    3. The attempt at a solution
    By slowing down the acceleration to a point where the force down would be less than 800.
    weight=m(g)
    1000N=m(9.8)
    102.04kg=m
    ∑F=ma
    799.99=102.04kg(a)
    7.84m/s^2=a
    Would this be the right answer?
     
    Last edited: Oct 11, 2015
  2. jcsd
  3. Oct 11, 2015 #2

    TSny

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    This is not the correct answer. Be sure to draw a free body diagram of the object. How many forces act on the object as it is being lowered?
     
  4. Oct 11, 2015 #3
    The two forces are weight and force tension. Where did I go wrong exactly?
     

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  5. Oct 11, 2015 #4

    TSny

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    Diagram looks good. When you set up ∑F = ma, the left side represents the vector sum of the two forces.
     
    Last edited: Oct 11, 2015
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