Finding Forces in Truss Members Using Method of Sections

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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.
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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.
 
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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.
 
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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 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
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