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Free Body Diagram

  1. Mar 7, 2009 #1
    hey, i just want a confirm if this is correct. imagine a built-in or a fixed bar in the side of a wall. when drawing a free body diagram for the point where the wall and the bar are fixed there should be forces in both x and y and a moment of force. if we label the x and y forces on the bar, does it matter on which direction we define it as?
    Code (Text):

    ie

    ^  Ay                                                      
    |                                                            
    |                                                    
    |                                                        
    |----------->    Ax        


                OR


     | Ay
     |
     |
     |
    \|/ <-----------  Ax                        
               
     
    cuz, if you solve for Ax or Ay, even if it's -ve, it just means that positive motion is acting in the opposite direction....right?

    any help would b appreciated.
    cheers,
     
  2. jcsd
  3. Mar 7, 2009 #2
    Physics is invariant under coordinate transforms, especially linear non accelerating coordinate transforms like this.
     
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