Free Body Diagram

unknown_2
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:
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,

Answers and Replies

Klockan3
Physics is invariant under coordinate transforms, especially linear non accelerating coordinate transforms like this.