# 3D Equillibrium Statics Problem - Reaction Forces/Moments

• mjgarrin
In summary, the student is having difficulty determining the reaction forces and moments in a rigid body. He has included a sketch of his problem, and is hoping someone can help him to solve it. The student has added a fixed rod to the equation, and is not sure the moments are accurate.
mjgarrin
Hello, it has been quite some time since my statics class, and I am having a problem determining the reaction forces and moments in a rigid body. I have included a sketch of my problem, and I am hoping someone can help guide me to a solution. I apologize if the sketch is a bit crude.I have a beam that is fixed at one end. On the opposite end, there is a vertical force acting directly on the beam (F1 = 1,000 lbf), and a horizontal force acting on a bar attached to the beam (F2 = 250 lbf).

The beam is supported by a roller, and has a reaction load in the vertical directly only, located 30 inches from the end of the beam.

The beam is also supported by a rod, located 12 inches from the fixed support, and the rod is at an 18 degree angle.

I am trying to find the reaction Forces as well as the Moments to show this scenario in static equilibrium.

Thank you.

#### Attachments

• Statics problem.png
19.2 KB · Views: 413
Can you describe the application? 1000 pounds is a lot of force...

I just gave made up numbers just to get an idea how to solve such a problem. I agree, the forces may not translate well to the size of the beam. Any force would work.

Sum forces in the x, y, and z directions and equate to zero. Also choose a convenient point(s) to sum moments around and equate to zero. Start here and let's see how many unknowns you have. Also since it's a 3D system I would recommend using cartesian vector notation.

I think the added fixed rod is causing me some issues. I tried summing the forces and moments, and got the following in the attached sketch. I think the forces are right, but I am not sure the moments are accurate...

#### Attachments

• Statics problem2.png
38.2 KB · Views: 414

## What is a 3D equilibrium statics problem?

A 3D equilibrium statics problem involves analyzing forces and moments in a three-dimensional space to determine the stability and balance of a system. This is often used in engineering and physics to design structures and predict their behavior under different conditions.

## What are reaction forces and moments?

Reaction forces and moments are the forces and moments that act on a structure or object in response to an external force or moment. These are equal and opposite to the external forces and moments and are necessary for an object to maintain its equilibrium.

## How do you calculate reaction forces and moments?

Reaction forces and moments can be calculated using the principles of Newton's laws of motion and the equations of static equilibrium. This involves analyzing all the external forces and moments acting on an object and setting them equal to the reaction forces and moments to solve for their values.

## What factors can affect the reaction forces and moments in a 3D equilibrium statics problem?

The reaction forces and moments in a 3D equilibrium statics problem can be affected by several factors, including the magnitude and direction of the external forces and moments, the geometry and material properties of the object, and the supports and constraints in the system.

## What are some common applications of 3D equilibrium statics problems?

3D equilibrium statics problems are commonly used in engineering and physics for designing structures such as bridges, buildings, and machines. They can also be applied in analyzing the stability of objects in various scenarios, such as determining the maximum weight a shelf can hold or predicting the behavior of a rocket during launch.

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