(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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").

2. Relevant equations

3. 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.

Thanks,

Brad

View attachment problem 6.bmp

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# Forces on a Truss

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