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Homework Help: Work and kinetic energy help

  1. Oct 11, 2005 #1
    Hi there, I'm new here, and I desperately need help with this work/energy business. Here's my problem:

    A mail bag with a mass of 140 kg is suspended by a vertical rope of length 8.00 m.
    a) What horizontal force is necessary to hold the bag in a position displaced sideways a distance 3.00 m from its initial position?
    b) How much work is done by the worker in moving the bag to this position?

    I know that the angle from the vertical will be 22 degrees, and that the tension in the rope will be 1272 N (or am I wrong?), but I don't know where to go from there.

    By the way, this is for a Mastering Physics problem, and I've already found out that 476.5 N [1272*cos(68)]is a wrong answer.

    Thank you!
  2. jcsd
  3. Oct 12, 2005 #2


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    Homework Helper

    You got the tension wrong, that's all. It looks like your method is OK.
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