# 3D statics - is there a simpler, shorter way to solve problems?

• Femme_physics
In summary: I once had a program (Windows 3.1) called Design View.It was a marvelous program that allowed you to draw vectors and automatically prepared a spreadsheet for you and performed the calculations straight off your drawing.If you then amended the spread sheet it would amend the drawing or if you amended the drawing it would recalculate the spreadsheet.That sounds like something that would be very helpful. :)
Femme_physics said:
Do I have to do three 2D free-body-diagrams like I did here ->

https://www.physicsforums.com/showthread.php?t=503368 Or is there a shortcut?

I take it you mean these drawings?
http://imageshack.us/photo/my-images/41/3dattempt.jpgWell, there is a method using 3D vectors and outer vector products, but I think you did not meet those friends yet.
And even with them, you're actually doing the very same thing!

So the answer, in my humble opinion, is: no, there is no shortcut.
You have to make all 3 drawings.

On the other hand, your calculations could have been a bit shorter.

Yes I meant those drawing."On the other hand, your calculations could have been a bit shorter.
"

How?

You kept using trigonometry, to calculate force components from lengths.
This is not necessary.

It's simplest if you always use the force components, like Tx, Ty, Tz.
And that you do not keep calculating from a projection of T with an angle.

True, but that can be said of 2D's as well. This is not the part that really delays me I just want to write things in details. :)

What I saw my lecturer do in class quite baffled me. He did sum of all moments to the AXIS! I didn't think that was possible..? So I was fairly confused in class.

Femme_physics said:
True, but that can be said of 2D's as well. This is not the part that really delays me I just want to write things in details. :)

What I saw my lecturer do in class quite baffled me. He did sum of all moments to the AXIS! I didn't think that was possible..? So I was fairly confused in class.

Let me see if I can explain.

A "moment" is a measure how strongly a body will rotate.
In 2D a body will rotate around a point.
In 3D a body will rotate around an axis.
When you make a 2D drawing from a 3D problem, the 3D axis turns into a 2D point.

If you have a pole and look at it, it looks like a line doesn't it?
Now if you keep the pole straight away from your eye, it starts to look like a point, does it not?

If you want to calculate a moment in 3D in respect to a specific axis, you can make a 2D projection along the axis and do it as you're used to.
Or you can try and calculate the various distances to this axis in 3D.

In 2D a body will rotate around a point.
In 3D a body will rotate around an axis.
When you make a 2D drawing from a 3D problem, the 3D axis turns into a 2D point.

I see.

[/quote]
Or you can try and calculate the various distances to this axis in 3D.
[/quote]

I don't think it's all that difficult to do, but calculating moment to an axis gives me more unknowns, no?

I'll show what I mean in a 3D statics problem I'll post.

I'm sorry to break it to you that much (even most) engineering calculation is copious tedious repetition of some simple formula.
Of course, since it is simple, it lends itself well to automatic (computer) calculation and there are many computer programs available to do just that.

But you still need to understand what the computers are doing otherwise garbage in = garbage out.

I once had a program (Windows 3.1) called Design View.

It was a marvelous program that allowed you to draw vectors and automatically prepared a spreadsheet for you and performed the calculations straight off your drawing.
If you then amended the spread sheet it would amend the drawing or if you amended the drawing it would recalculate the spreadsheet.

Marvelous, but I have never managed to get it to run successfully on later versions of Windows, although I still keep the original disks.

## 1. What is 3D statics and why is it important?

3D statics is a branch of mechanics that deals with the analysis of forces and moments acting on three-dimensional objects in a state of equilibrium. It is important because it allows us to understand the behavior of structures and objects under different loading conditions, which is crucial in fields such as engineering, architecture, and physics.

## 2. Can 3D statics problems be solved using a simpler and shorter method?

Yes, there are various methods and techniques that can be used to simplify and shorten the process of solving 3D statics problems. Some common methods include using vector algebra, simplifying complex structures into smaller components, and utilizing symmetry and equilibrium principles.

## 3. Is there a specific formula or equation for solving 3D statics problems?

No, there is no one specific formula or equation for solving 3D statics problems. The approach to solving these problems depends on the specific problem at hand and may involve a combination of equations, principles, and techniques.

## 4. How can I improve my understanding of 3D statics?

To improve your understanding of 3D statics, it is important to have a strong foundation in vector algebra, trigonometry, and mechanics. It is also helpful to practice solving various types of problems and to seek guidance from textbooks, online resources, or a tutor.

## 5. Can 3D statics be applied to real-world situations?

Yes, 3D statics is commonly used in real-world situations, especially in fields such as engineering and architecture. It is used to analyze and design structures such as buildings, bridges, and machines, and to ensure their stability and safety under different loading conditions.

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