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Homework Help: 3D sum of forces/static object

  1. Oct 5, 2011 #1
    1. The problem statement, all variables and given/known data
    A Bob is centered on a force plate attatched to three pulleys of different heights by string. these pulleys are located at 360*, 270* and 140* on the plate with masses to make the bob centered of .075kg, .054, and .080 respectively. The measured angles for each string were 46.4*, 41.5*, and 35.6* The object is to see how close to a theoretical 0 net force equilibrium we can get. The Bob weighs .1375kg.

    2. Relevant equations
    string A: .075*9.8=.74N, angle was measured to be arctanΔ6.3/Δ6=46.4*. Then for the horizontal force I have X=.74sin46.4=.54N. Y=.74sin46.4=.51 and I am unsure how to get the Z force. This is where I am stuck. I have completed the previous equations for all 3 strings and for the x and Y vectors by using FTx=ƩFx-Fbob=1.54-1.34=.2, Fty=ƩFy-Fbob=0. I am really stuck. Any help would be appreciated. Thanks.
  2. jcsd
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