Solve Force in Member HE: Trusses Homework

In summary, the conversation is about determining the force in member HE for a truss. The attempt at a solution involves solving for the reaction forces at G and using them to find the force GF. The system of equations for this is solvable despite having both GH and GF with x and y components. The number of unknowns and equations allows for a solution to be found.
  • #1
jlg
2
0

Homework Statement


Determine the force in member HE for the truss in the figure. All members are length 0.8m except GH.
570.jpg


The Attempt at a Solution


I solved for the reaction forces at G and got Gx = 1039 N , Gy = -1200 N, A = 1800 N. My professor said to then draw a FBD of G and solve for GF. Am I crazy or is that unsolvable because both GH and GF have an x and y component, so I'd be left with something like:

Fx = GFsin + GH sin = 1039
Fy = GFcos + GH cos = -1200
 
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  • #2
jlg said:
Am I crazy or is that unsolvable because both GH and GF have an x and y component, so I'd be left with something like:

Fx = GFsin + GH sin = 1039
Fy = GFcos + GH cos = -1200

How many unknowns do you have? How many equations do you have? The above system of equations is very solvable.
 
  • #3


I would first like to commend your efforts in solving the truss problem and seeking clarification from your professor. It is important to have a clear understanding of the problem before attempting to solve it.

You are correct in your thinking that the forces in members GH and GF cannot be solved simultaneously with the given information. This is because there are two unknowns (GF and GH) and only two equations (Fx and Fy). In order to solve for both forces, we would need additional information, such as the angle of inclination for each member.

In this case, it seems like your professor is asking you to solve for the force in member GF by considering the equilibrium of forces at point G. This means that you will need to draw a free-body diagram of point G and use the equations of equilibrium (ΣFx = 0 and ΣFy = 0) to solve for GF.

I suggest discussing this further with your professor to clarify the instructions and see if any additional information can be provided to help solve for both GH and GF. It is also important to note that truss problems can have multiple solutions, so your professor may be looking for a specific approach or solution method.

In conclusion, your thinking is correct and it is not possible to solve for both GH and GF with the given information. Keep up the good work and continue to seek clarification and guidance from your professor.
 

1. What is a truss in engineering?

A truss is a structural element that consists of interconnected members forming triangular shapes. It is commonly used in engineering and construction to support loads and reinforce structures.

2. How do you solve for forces in a truss member?

To solve for forces in a truss member, you can use the method of joints or the method of sections. In the method of joints, you analyze the equilibrium of each joint to determine the forces in the members connected to it. In the method of sections, you cut the truss into sections and analyze the equilibrium of each section to determine the forces in the members.

3. What is the difference between tension and compression in truss members?

Tension is a pulling force that elongates or stretches a material, while compression is a pushing force that shortens or compresses a material. In truss members, tension and compression are opposite forces that work together to resist external loads and maintain the stability and integrity of the truss structure.

4. How do you determine the load bearing capacity of a truss?

The load bearing capacity of a truss depends on various factors such as the material properties, the design and configuration of the truss, and the type and magnitude of the loads applied. To determine the load bearing capacity, engineers use mathematical calculations and computer simulations to analyze the stress and strain distribution within the truss and ensure that it can withstand the expected loads.

5. Can a truss fail?

Yes, a truss can fail if it is not designed and constructed properly or if it is subjected to loads that exceed its load bearing capacity. Common causes of truss failure include inadequate support, excessive loads, material defects, and construction errors. It is important for engineers to carefully design and analyze truss structures to ensure their safety and stability.

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