# Find Reactions of 4000lb Crate in Truss Figure 1

• kennyvs
In summary, the problem involves a 4000lb crate attached to a truss by light inextensible cables. The goal is to determine the reactions at joints A and E of the truss. The Moment arm equation is used to find the Fx and Fy forces at these joints. There are no supports at joints B, D, and C, so there are no reactions at those joints. The joint forces must sum to 0, and the member forces can be determined by considering the forces at each joint.
kennyvs

## Homework Statement

A 4000lb uniformly weighted crate is attached by light inextensible cables to the trus show below. Simply determine the reaction at A and E of the truss show below

Figure 1 attachment

## Homework Equations

I used the Moment arm equation of M = F*Distance

## The Attempt at a Solution

I know how to find out the Fx and Fy force of A and E, but I am having trouble determine the Fx and Fy force of B D C

#### Attachments

• Figure 1.JPG
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Last edited:
Hi, kennyvs, welcome to PF!
The problem asks you to determine the reactions at A and E, which you know how to find. There are no supports at B, D, and E, therefore, there are no reactions at those joints. Are you trying to take this problem one step further by determining the member forces? Each of the joint forces must sum to 0. For example, at joint D, the cable exerts a 2000 pound downward pull on the joint, so the member BD must exert an upward pull of 2000 pounds on that joint. But I'm not sure what you are trying to do.

I think i got what i need to complete the assignment. Initially I don't know what the force at B D C are, but knowthnx to your reply ^^ now i can find moment A with the force from joint B, D, C. Thnx

## 1. What is the purpose of finding reactions of a 4000lb crate in truss Figure 1?

The purpose of finding reactions in a truss structure is to determine the forces acting on each member of the truss. This information is crucial in ensuring the structural integrity and stability of the truss.

## 2. What is the process for finding reactions in a truss structure?

The process for finding reactions in a truss structure involves applying the principles of statics, specifically the equations of equilibrium, to determine the unknown forces acting on the truss members. This typically involves breaking down the truss into smaller sections and solving for the reactions at each support.

## 3. How does the weight of the crate affect the reactions in the truss?

The weight of the crate will add a downward force on the truss, which will in turn affect the reactions at each support. The magnitude and direction of these reactions will depend on the position of the crate within the truss.

## 4. Can the reactions in a truss structure be calculated by hand or is specialized software needed?

The reactions in a truss structure can be calculated by hand using the principles of statics. However, for more complex truss structures, specialized software such as finite element analysis may be needed to accurately determine the reactions.

## 5. How do the reactions of a 4000lb crate in truss Figure 1 impact the design of the truss?

The reactions of the 4000lb crate will influence the design of the truss as they determine the maximum load that the truss can support. If the reactions exceed the capacity of the truss, the design may need to be modified to ensure safety and stability.

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