Understanding Method of Sections: Why is Fy=2T2 - 981? | WikiBooks

  • Thread starter On Radioactive Waves
  • Start date
  • Tags
    Statics
In summary, the conversation is about the method of sections and a question regarding a factor of 2 in the equation Fy=0=2T2 - 981. The person is struggling to understand this concept and is seeking clarification. They also mention a previous discussion on the topic.
  • #1
On Radioactive Waves
137
0
Okay, so I am trying to understand the method of sections so I can finish my homework. I look at http://en.wikibooks.org/wiki/Statics/Method_of_Sections" and for the life of me, I can't understand why at the bottom of the page it says Fy=0=2T2 - 981 .

Where does the factor of 2 come from? Why not just T2? I feel like I am missing something completely obvious. Sorry for the poor notation.

I am posting this here because it is not my homework problem, and there is no work for me to show. I would just appreciate an answer, so I can do my homework. I'm totally missing the bus on this concept right now...
 
Last edited by a moderator:
Physics news on Phys.org
  • #3
Thanks.
 

FAQ: Understanding Method of Sections: Why is Fy=2T2 - 981? | WikiBooks

How is the equation Fy=2T2 - 981 derived?

The equation Fy=2T2 - 981 is derived using the method of sections, which is a technique used to solve for unknown forces in a truss or beam. The equation represents the sum of all vertical forces acting on a particular section of the truss, where 2T2 is the vertical component of tension in the two members that intersect at that section, and 981 is the downward force of gravity (981 N/m^2) acting on any objects attached to that section.

What do the variables T and Fy represent in the equation?

The variable T represents tension, which is the force acting along a member of the truss. Fy represents the sum of all vertical forces acting on a particular section of the truss, including the downward force of gravity and the vertical component of tension in the intersecting members.

Why is the downward force of gravity represented as a negative value in the equation?

The downward force of gravity is represented as a negative value because it acts in the opposite direction of the positive y-axis. In order to accurately calculate the sum of all vertical forces, the force of gravity must be subtracted from the positive forces acting in the vertical direction.

How does the method of sections help in solving for unknown forces in a truss?

The method of sections allows us to isolate a specific section of the truss and analyze the forces acting on it. By drawing a free body diagram and applying the equations of equilibrium, we can solve for the unknown forces in that section. This technique is particularly useful for trusses with multiple unknown forces that cannot be solved using the method of joints.

Are there any assumptions made when using the method of sections?

Yes, there are a few assumptions that are made when using the method of sections. These include: assuming the truss is in static equilibrium, assuming the members of the truss are perfectly straight and do not bend or deform, and assuming all joints are frictionless. These assumptions may not hold true in real-life situations, but they allow us to simplify the analysis and solve for unknown forces using basic principles of physics.

Similar threads

Engineering Moment of a force about point O
Replies
4
Views
2K
Static variable in static method - how to use?
Replies
3
Views
1K
I How is the direction of a harmonic wave expressed?
Replies
6
Views
1K
3-link planar manipulator: a statics conceptual question
Replies
1
Views
1K
Calculating Residue at -2: Math Methods w/ Arfken et al.
Replies
4
Views
1K
Understanding Tension on a Pulley
Replies
6
Views
2K
I How to understand experiment to measure heat capacity of solid?
Replies
1
Views
1K
Virtual Work and Static Equilibrium
Replies
3
Views
1K
Why is there a vertical force on the pin in this static equilibrium setup?
Replies
8
Views
2K
Is There an Easier Method for Solving Truss Problems?
Replies
1
Views
1K

Hot Threads

Recent Insights

Back
Top