# Number of total reactions in a structure

• fonseh
To determine the total reactions for this type of question, you need to consider all the external forces acting on the structure and the supports at the cut section.In summary, the author stated that the total reactions for the given example is 9 because there are 3 reactions at the cut section, 2 reactions at the pin support, and 1 reaction at the roller support, making a total of 9 reactions. To determine the total reactions for this type of question, one must consider all external forces and supports at the cut section.
fonseh

## Homework Statement

In the example A , Why the author stated the total reactions = 9 only ? How to determine the total reactions for this type of questions ?

## The Attempt at a Solution

we can see that there is a total of 3 reactions (vertical , horizontal and moment) at the cut of the 4 parts , right (circled part) , and 3 reactions below . So , the total reactions is 4x3 + 3 = 15.

#### Attachments

• 9.jpg
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When ever you have a closed loop as in this frame, you cut it, and you count the set of internal reactions (only once) as reaction forces.

Looking at the loop we get a total of 3+3 reactions (note that the internal reactions of AD and DA are the same and we do not count them as 6 , but 3 unique ones)
Looking at the supports , one is a pin ∴ 2 reactions and the other is a roller ∴ 1 reaction.

In conclusion, we have 3+3+2+1 =9 reactions

fonseh

## What is the definition of "Number of total reactions in a structure"?

The number of total reactions in a structure refers to the total number of chemical reactions that occur within a specific structure or system. These reactions can involve the breaking or forming of chemical bonds, resulting in a change in the structure's composition or properties.

## How is the number of total reactions in a structure determined?

The number of total reactions in a structure is determined through various methods, such as experimental analysis, computational simulations, or theoretical calculations. These methods involve examining the chemical components and interactions within the structure to identify and quantify the reactions that occur.

## Why is the number of total reactions in a structure important?

The number of total reactions in a structure is important because it provides insight into the complexity and functionality of the system. It can help scientists understand how the structure functions and how it may respond to different stimuli or changes in its environment. This information can be valuable in fields such as materials science, chemistry, and biology.

## Can the number of total reactions in a structure change?

Yes, the number of total reactions in a structure can change. This can occur due to external factors, such as temperature, pressure, or the introduction of new chemical components. It can also change over time as the structure undergoes natural processes, such as decay or aging.

## How does the number of total reactions in a structure relate to its stability?

The number of total reactions in a structure is closely related to its stability. A higher number of reactions indicates a more complex and dynamic system, which may be less stable. On the other hand, a lower number of reactions may indicate a more stable and structured system. However, stability also depends on other factors, such as the strength of chemical bonds and external forces acting on the structure.

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