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Conservation of Energy Question

  1. Jan 14, 2016 #1
    Having problems with part (c) here, question is attached below in full.

    1. The problem statement, all variables and given/known data
    Force%20in%20beams%20problem.png

    Using the equation 1/2 * Load * Displacement = Sum of (P^2 * L/2AE)

    From the past questions I have the following info, these are also included in the solutions so are accurate:

    A = 1x10^3 m^2
    FAB = 90kN
    FBC = 120kN
    Length of AB = 1.5 m
    Length of BC = 2 m

    2. Relevant equations

    3. The attempt at a solution
    My attempt at the solution:

    1/2 * 150 x 10^3 * Displacement = 1/(2 * 1x10^-3 * 205x10^9) * ((90x10^3^2 * 1.5)+ (120x10^3^2 * 2))

    Displacement = ((90x10^3^2 * 1.5)+ (120x10^3^2 * 2)) / 1x10^-3 * 205x10^9 * 150x10^3

    = 1.33 mm

    The correct answer, per the solutions, is 2.08 mm.

    Any idea where I've gone wrong?

    Thanks.
     
  2. jcsd
  3. Jan 14, 2016 #2
    Any ideas?
     
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