# Calculating Reactions A, B, and C for a Solid Desk - Helpful Tips and Solutions

• twoflower
In summary, the conversation is about someone trying to figure out the reaction of a solid desk based on a given picture. They need to compute the reactions A, B, and C at specific points on the picture, using known dimensions. The person has already computed the reaction C, but is struggling with calculating reactions B and A. They are asking for help in finding the right equations to use.
twoflower
Hi all!

## Homework Statement

What I'm trying to figure out is a reaction of a solid desk (don't know if this is the proper term) given this picture:

http://twoflower.matfyz.cz/inc/eng.gif

I need to compute the reactions A, B and C (they corresponding to points denoted by 'a', 'b' and 'c' on the picture.) The dimensions 'a', 'b' and 'c' are constants and I know them.

## The Attempt at a Solution

So far I computed the reaction C from this equation:

$\cos 60 * F_3 + C*\sin 30 = 0$

But I cannot figure out, how to compute the reaction B and A, I can't put the right equations together...

Could someone please point me to the right direction?

best regards.

Last edited by a moderator:
Form an equation of the sum of moments with respect to points a and b.

Hello there,

It looks like you are trying to calculate the reactions for a solid desk given a picture and known dimensions. This is a common problem in structural analysis, and there are a few helpful tips and solutions that may assist you in finding the correct equations to use.

Firstly, it's important to identify all the forces acting on the desk. In this case, we have the weight of the desk itself (F_3), the force at point C (reaction C), and the forces at points A and B (reactions A and B). These forces can be represented by vectors, with their magnitudes and directions.

Next, you can use the principles of statics to solve for the unknown reactions. This means that the sum of all forces in the x and y directions must equal zero, and the sum of all moments must also equal zero. By setting up and solving these equations, you should be able to find the values for reactions A and B.

It may also be helpful to draw a free body diagram, which is a simplified representation of the forces acting on the desk. This can help you visualize the problem and identify any missing information.

I hope this helps guide you in the right direction. Good luck with your calculations!

## 1. What is the reaction of a solid desk?

The reaction of a solid desk refers to how the desk responds to different external forces, such as weight, pressure, or temperature changes.

## 2. How does the material of the desk affect its reaction?

The material of the desk can greatly affect its reaction. For example, a wooden desk may expand or contract in response to changes in humidity, while a metal desk may be more resistant to these changes.

## 3. Can the reaction of a solid desk be altered?

Yes, the reaction of a solid desk can be altered by changing its material, shape, or size. Additionally, adding support structures or reinforcements can also affect its reaction.

## 4. How do scientists study the reaction of a solid desk?

Scientists may use various methods, such as conducting experiments, performing simulations, or using mathematical equations, to study the reaction of a solid desk. They may also analyze the desk's structural properties and materials to better understand its reaction.

## 5. Why is it important to study the reaction of a solid desk?

Studying the reaction of a solid desk can help us understand the behavior of different materials and structures under different conditions. This knowledge can be applied in various industries, such as construction and design, to create more durable and efficient structures.

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