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Homework Help: Mass hanging in a boxcar accelerating

  1. Apr 8, 2016 #1
    1. The problem statement, all variables and given/known data
    A mass of 1 kg hangs inside a boxcar of a train. If the train accelerates at 7 m/s^2, what is the approximate tension in the rope?

    A: 12 N

    2. Relevant equations

    3. The attempt at a solution
    I originally thought of doing this problem as pythagorean theorem, but I wanted to work out the x and y components for practice. Breaking up the components:
    Ty-mg = may


    Thus, T2=102+702
    T=71 N

    The problem sets it up just like I do but get 12 N for their answer:

    What am I doing wrong? Thanks in advance!
  2. jcsd
  3. Apr 8, 2016 #2


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    Staff: Mentor

    Can you show us your free body diagram for this problem? That is generally the first/best step on these problems. :smile:
  4. Apr 9, 2016 #3


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    Staff: Mentor

    Check the mass value used for the calculation of the x-component.
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