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In tearing a paper towel or plastic bag

  1. Sep 8, 2012 #1
    1. In tearing a paper towel or plastic bag from a roll, why is a sharp jerk more effective than a slow pull



    2. I found this answer online

    A quick, sharp jerk means a greater acceleration and a greater acceleration means a greater force. And it is force that tears the paper towel or plastic bag


    3. The attempt at a solution

    I was thinking not only the force of the jerk like the answer online said but wouldn't it be as well because the roll is ƩF = 0 and the quick acceleration of the one piece while the rest remain unmoved?

    I don't know if that is confusing sorry if it is.
     
  2. jcsd
  3. Sep 8, 2012 #2

    CWatters

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    Is the roll free to rotate?

    If so ask yourself why the paper would ever tear?
     
  4. Sep 8, 2012 #3
    I am making an assumption saying it is free to rotate, every single one I have encountered is. usually it tears because of the perforated edges. As well as I am assuming that the force and the jerk kind of the theory of the bus - when the bus accelerates you move forward and when it decelerates you move backward. the paper towel that you grabbed in my mind has the same theory its moving at a constant rate with a sudden change.
     
  5. Sep 8, 2012 #4

    CWatters

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    I think the word you are looking for is "Inertia".
     
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