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Homework Help: Free body diagram of man in a box

  1. Oct 5, 2012 #1
    1. The problem statement, all variables and given/known data
    A 60 kg man stands in a 30 kg box on a light weighing machine.
    If the box is kept at rest due to force applied by the man by the rope , what is the weight shown by the weighing machine?

    2. Relevant equations

    3. The attempt at a solution
    .answer given in book is 15 kg.
    But if the net force man i think will his weight-weight of the box=300N
    I don't think i am proceeding correctly.
    I just need a hint for the free body diagram.
    Thanks in advance

    Attached Files:

  2. jcsd
  3. Oct 5, 2012 #2


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    Science Advisor
    Homework Helper

    hi 1/2"! :wink:

    as often in these problems, you need two free body diagrams …

    in this case, one for the man (on his own), and one for the man-and-box …

    how many external forces forces are there in each case? :smile:
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