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Homework Help: Determine the distance of the center of gravity from the end X of the plank?

  1. May 18, 2008 #1
    1. The problem statement, all variables and given/known data
    A non-uniform plank of wood XY is 2.50m long and weighs 950N. Force-meters (spring balances) A and B are attached to the plank at a distance of 0.40m from each end, as illustrated in the Figure below

    http://img266.imageshack.us/img266/2377/physicsp23bgh5.png [Broken]​
    [/URL]
    When the plank is horizontal, force-meter A records 570N

    (i) Calculate the reading on force-meter B
    (ii) Determine the distance of the center of gravity from the end X of the plank.

    2. Relevant equations
    Moment = Force x Perpendicular Distance

    3. The attempt at a solution
    (i) [tex]A + B = 950N[/tex]
    [tex]B = 950 - 570 = 380N[/tex]

    (ii) I don't know how to solve this question, need help! :frown:
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. May 18, 2008 #2

    CompuChip

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    Science Advisor
    Homework Helper

    In equilibrium, all the moments (A, B, gravity) cancel out.
     
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