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Homework Help: HELP! Simple center of Gravity problem

  1. Mar 16, 2009 #1
    2) A Uniform Boars has a mass of 1.5kg and length of 100cm, Note the Weight is negligible.

    A) Where should it be supported so that it will balance a 10g mass places at an end, a 60kg mass on the other end, and a 40kg mass placed 30 cm to the 10g mass?

    The answer should be 0.511m

    a. First you need to convert all g to kg and cm to m


    (10g)(1X10-3kg1g) = 0,010kg

    (40g)(1X10-3kg/1g) = 0.040kg

    (60g)(1X10-3kg/1g) = 0.060kg

    (30cm)(1X10-2m/1cm) = 0.30m

    (100cm)(1x10-2m/1cm) = 1.0m

    (0cm)(1x10-2m/1cm)= 0 m

    Using the center of mass equation you get

    Xcg = W1X1 + W2X2 + W3X3 / W1 + W2 + W3


    Xcg = (0.010kg)(0m) + (0.060kg)(1.0m) + (0.040kg)(0.30) / (0.010kg) + (0.060kg) + (0.040kg)

    = 0.0720kg.m / 0.110 kg

    = 0.645 m

    I am not sure where I went wrong and why I have a higher number then the answer. Any help would be great!

    thank you!!!
  2. jcsd
  3. Mar 16, 2009 #2


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    Homework Helper

    Sorry, I don't understand your units. What are they g's or kg? They looked mixed in your use of them.

    Also the mass of the board is not insignificant. Is this another typo?
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