Need help clarifying statics problem.

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In summary, the conversation discusses the process of finding the magnitude of the internal force in member BC. The speaker mentions solving for the reaction forces at A and D, and suggests using a free body diagram to find the horizontal and vertical components of force at B and C. However, another speaker points out that this method may not work due to the truss being subject to bending. The conversation concludes with a discussion on why taking the moment is necessary in this situation.
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jackspicer
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Homework Statement


What is the magnitude of the internal force in member BC?

Homework Equations


So I figured out the reaction force at A and D by taking the moments about point A to find the vertical force at D and then summing the x and y components to find the forces at A.

The Attempt at a Solution



So I solved for the reaction forces for A, and D already. Why can't I split the truss into three members? Why can't I take member AD and have a free body diagram for that member and solve for the Fx and Fy for Bx and By by summing the forces? Do I absolutely have to take the moment? Can I not do

Ax-Bx=0
Ay-By+Dy=0

To find the components of B? This method doesn't seem to work.
Why do I have to take the moment?
 
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  • #2
This is not a pure truss since the horizontal and vertical members are subject to bending. When taking a FBD of AD, you must include the horizontal component of force at D, found by first taking a FBD of the vertical member.
 

FAQ: Need help clarifying statics problem.

1. What is the purpose of statics in science?

Statics is a branch of mechanics that deals with the study of objects at rest or in a state of constant motion. It is used to analyze and predict the behavior of structures and systems under various forces and loads.

2. How is statics different from dynamics?

While statics deals with objects at rest or in a state of constant motion, dynamics deals with objects in motion and the forces that cause that motion. Statics is concerned with the balance of forces while dynamics is concerned with the change in motion caused by those forces.

3. How do I approach solving a statics problem?

The first step in solving a statics problem is to identify all the external forces acting on the object or system. Then, apply the principles of equilibrium to determine the unknown forces or reactions. Make sure to draw accurate free body diagrams and use the appropriate equations and concepts for the given problem.

4. What are some common mistakes when solving statics problems?

Some common mistakes include not properly labeling forces or using incorrect units, not considering all the external forces, and not using the correct equations for the given problem. It is also important to check for mathematical errors and to make sure the final answer makes sense in the context of the problem.

5. Are there real-world applications of statics?

Yes, statics has many real-world applications in engineering, architecture, and construction. It is used to design stable structures such as bridges, buildings, and machines. It is also used in the analysis of forces in sports equipment and vehicles, and in the design of prosthetics and other medical devices.

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