Finding Forces in Truss Members Using Method of Sections

  • Thread starter Thread starter J-dizzal
  • Start date Start date
  • Tags Tags
    Method Trusses
AI Thread Summary
The discussion revolves around determining the forces in truss members BC and CG using the method of sections. A participant is struggling with their calculations, specifically questioning their angle θ and the assumption of member CH as a zero-force member. They initially calculated a tension of 3.66N, but this was deemed incorrect due to miscalculations related to the asymmetrical loading of the structure. Feedback highlights that the reactions Ay and Fy were incorrectly assumed to be 14 kN. The conversation emphasizes the importance of accurately assessing loading conditions in truss analysis.
J-dizzal
Messages
394
Reaction score
6

Homework Statement


Determine the forces in members BC and CG. The forces are positive if in tension, negative if in compression.
20150715_190800_zpseupbftpt.jpg

Homework Equations


ΣF=0
ΣM=0

The Attempt at a Solution


20150715_190729_zpszsi20agz.jpg

im not sure what I am doing wrong here, i think it might be my angle θ?
I got 3.66N tension as my answer but its wrong, i just started trusses and not sure what I am doing wrong.
 
Last edited:
Physics news on Phys.org
Im working on a similar problem and am making the same mistake, maybe CH needs to be found? but i think its a zero force member.
 
J-dizzal said:

Homework Statement


Determine the forces in members BC and CG. The forces are positive if in tension, negative if in compression.

Homework Equations


ΣF=0
ΣM=0

The Attempt at a Solution


20150715_190729_zpszsi20agz.jpg

im not sure what I am doing wrong here, i think it might be my angle θ?
I got 3.66N tension as my answer but its wrong, i just started trusses and not sure what I am doing wrong.
Your calculations appear to state that Ay = Fy = 14 (kN?)

The structure is not loaded symmetrically, so these reactions are incorrect.
 
  • Like
Likes J-dizzal
SteamKing said:
Your calculations appear to state that Ay = Fy = 14 (kN?)

The structure is not loaded symmetrically, so these reactions are incorrect.
thank you sir.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

How do I calculate forces in a truss cross section?
Replies
2
Views
578
How to Determine Forces in Members BC and CG Using the Section Method?
Replies
1
Views
4K
Is There an Easier Method for Solving Truss Problems?
Replies
1
Views
2K
Statics: Statically Indeterminate Unstable Plane Truss
Replies
4
Views
5K
How to check the Stability of ANY Truss?
Replies
1
Views
2K
Help understanding how to determine Compress or Tension in Truss
Replies
3
Views
7K
Truss-Member Forces- Method of sections
Replies
1
Views
4K
Statics: Forces in a truss, method of joints
Replies
3
Views
7K
Solve Truss Joints Using Method of Joints
Replies
6
Views
3K
What do the numbers in the method of joints analysis for trusses represent?
Replies
3
Views
3K

Hot Threads

Recent Insights

Back
Top