# Unusual problem for my course and struggling

• Mechanical94
In summary, the conversation discusses the support and design of a boom AC, which is connected to a bracket at C by a high-strength steel pin. The design critical components are the rectangular bar BD and the pin at C, with factor of safety values of 3.0 and 3.3, respectively, against failure. The required thickness of the bar BD (with width b) and the diameter of the pin at C need to be determined. The known data includes a load of 10 kN, a length of 3 m, a height of 2 m, b = 25 mm, and a shear stress of 250 MPa for the bar and 400 MPa for the pin. The method of using
Mechanical94
A boom AC is supported by a rectangular steel bar BD, and it is attached to a bracket at C by a high-strength steel pin. Assume that the pin at B is adequate to sustain the loading applied to it, and that the design critical components are the bar BD and the pin at C. The factor of safety against the failure of BD by yielding in uniaxial tension is 3.0. The factor of safety against a shear failure of the pin at C is 3.3. Determine the required:

a) Thickness, t of the rectangular bar BD, whose width is b; and, b) Diameter, d, of the pin at C.

known data

P = 10 kN,
L = 3 m,
h = 2 m
Bar BD: b = 25 mm,
shear stress = 250 MPa
Pin C: = 400 MPa

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this is my efforts on this question i believe i have part a correct in this however i can't piece together how to do part b in it

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Mechanical94 said:
this is my efforts on this question i believe i have part a correct in this however i can't piece together how to do part b in it

That's fairly hard to read. We prefer that you type your work into the forum posts (preferably with Latex, but at least type in the equations). If you could take a closer picture of your figure (or scan it), that would be a help too. Thanks.

hopefully these photos are clearer, i got an answer of 12mm for the thickness and cannot get a solution to part b

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The dimensions used in your answer don't match with the symbolic notation used in the question. You could try using the property that when a body is acted upon by three forces that are in equilibrium, then they must all meet at one point (otherwise there is a turning moment). You could use that property to determine the force on the hinge at C. Even if you don't do it that way, the method I suggest acts as a check on the method you do use.

so my answer of 12mm was incorrect?

## 1. What can I do if I am struggling with an unusual problem in my course?

If you are struggling with an unusual problem in your course, the first thing you should do is reach out to your professor or teaching assistant. They will be able to provide you with guidance and resources to help you understand and solve the problem.

## 2. How can I approach an unusual problem in my course?

When approaching an unusual problem in your course, it is important to break it down into smaller, more manageable parts. This will help you to identify the key concepts and tackle each part systematically.

## 3. What resources are available to help me with an unusual problem in my course?

There are several resources available to help you with an unusual problem in your course. These may include textbooks, online tutorials, study groups, and office hours with your professor or teaching assistant. Utilizing these resources can provide you with a better understanding of the problem and potential solutions.

## 4. What should I do if I am still struggling with an unusual problem after seeking help?

If you are still struggling with an unusual problem after seeking help, try approaching it from a different angle. Sometimes, a fresh perspective or a different approach can help you to see the problem in a new light. You can also try discussing the problem with your classmates to gain new insights and ideas.

## 5. How can I prevent struggling with unusual problems in the future?

To prevent struggling with unusual problems in the future, it is important to stay organized and keep up with your coursework. Make sure to attend lectures and take thorough notes, and review your notes regularly. It can also be helpful to practice problem-solving techniques and seek help early on if you encounter any difficulties.

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