Ok, you'll have to wait for my picture. Basically we are doing trusses, and I'm not sure where I'm going wrong here.
We are to find the tension/compression in each member(line) of the truss.
Ok, from my picture. F1 is directly at B(in neg y direction), and is 2800N. F2 is at point D(in the neg x direction) and is 2100N.
The distances between A&B, and B&C are 4m. A is a pin system(basically has x and y forces).....and C is held up by a cable(I believe only supports in the y direction).
I also drew another picture, which consists of little circles on each joint, and arrows pointing in the directions of the tensions(and forces acting on the "circles").
The Attempt at a Solution
Ok, I'm only going to post some of this, to see if I started correctly(where I think I messed up).
So, from my picture, I took overall equilibrium. So, I chose to sum moments about point A=0(with a counter-clockwise rotation I chose).
moments at pt A = 0= 8Cy -2800(4) - 2100(3.4641)
Cy = 1259.33N up
Sum Forces in +x direction=0
Ax - 2100 = Ax=2100N to the right
Sum forces in +y direction = 0
Ay + Cy - 2800 = Ay = 1540.67N up
If this is correct, then I'll post more. Next, I drew that other picture, and started at points and found the tension(as I draw them all in tension to begin with) at each point.
View attachment problem 6.bmp