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Homework Help: A beam question

  1. Jun 7, 2005 #1
    ok, i don't know how to start this problem :blushing:

    the beam in the drawing weighs 3000 kg. It is attached to the wall by means of a simple union and without friction in point A. It is attached to the wall by means of a cable CD. The moment applied in point B is 6000 kg*m. Calculate graphically the force in point A and tension in cable CD:

    lots of questions here:

    0) when they say graphically... what exactly do the mean? you know, that you have to draw the lines with their exact length and their angle and with a ruler measure the resultant force...

    1) UNITS: the kilograms here are kilograms force?, or should i convert them to newtons?

    2) REACTION IN POINT A: I assume there will be a reaction in the X and Y axis.

    3) the main question here is: the momentum applied, how should i consider it when balancing the forces, does this thing have to do with flexural moments and that stuff? or i just translate the momentum applied to F*d?

    thanks in advance for any help you can give me

    Attached Files:

  2. jcsd
  3. Jun 7, 2005 #2


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    Homework Helper

    Remember that unlike the force, that can only move along its line of action without doing a force-couple (force momentum) system, the momentum is a free vector and you can put it anywhere.

    The momentum will only affect the sum of moments equation.

    [tex] \sum \tau [/tex] also represented as [tex] \sum M [/tex]

    Notice calculating sum of momentum on point B, won't make it 0 (It's a Free Vector).
  4. Jun 7, 2005 #3
    thanks a lot, i really appreciate it

    and i really hope you're Somewhere in the Sunny Caribbean

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