Solving 3D Statics Problem: Calculating Tension and Reactions

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The discussion focuses on solving a 3D statics problem involving a rectangular board supported by clutching devices and a cable. Participants emphasize the importance of treating the problem as 3D rather than simplifying it to 2D, highlighting the need to account for all force components and moments. The calculations for tension in the cable and reactions at the supports are discussed, with participants correcting each other's misunderstandings about the forces involved. There is also a debate about the accuracy of the solution manual's answers, particularly regarding the values of forces at the supports. Ultimately, the conversation reinforces the complexity of 3D statics and the necessity of careful analysis in such problems.
  • #31
Femme_physics said:
Okay my Bz is off

Can you tell me why?

You're using T, but what you should use, is Tx and Tz.
 
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  • #32
Oh, right! Hah, see it's tricky! ;)Thanks, working on it!
 
  • #33
Femme_physics said:
Oh, right! Hah, see it's tricky! ;)


Thanks, working on it!

Yeah, I know.
It's like bending your mind into a new direction it's not accustomed to! :smile:

Welcome to the world of 3D!

And perhaps you'd also like "Flatland" (see for instance http://en.wikipedia.org/wiki/Flatland" ), where you need your mind to get rid of a dimension! :cool:
 
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  • #34
Woah, I've been living in a 2D world this whole time, there's a whole new world open in front of me! Unbe*******livable!

I'm scared. Mom?:bugeye:
 
  • #35
Femme_physics said:
Woah, I've been living in a 2D world this whole time, there's a whole new world open in front of me! Unbe*******livable!

I'm scared. Mom?:bugeye:

And?
Did it help?
Could your mom protect you from the third dimension (wait till you get to the fifth!)
Or could she help you to understand it? :smile:

Or are you on your own exploring the world!
 
  • #36
It's kinda very scary in here...things go to the left and to the right, and up and down, but then...they also go into the page and out of the page! I'm scared of going into the page with those vectors... I need someone to protect me... no, not mommy, she's kinda still scared of 1D world. I need someone with the fortitude, skill and knowledge to deal with the monsters of the 3rd dimension! They can be scary for a 3D newbie!
 
  • #37
Femme_physics said:
It's kinda very scary in here...things go to the left and to the right, and up and down, but then...they also go into the page and out of the page! I'm scared of going into the page with those vectors... I need someone to protect me... no, not mommy, she's kinda still scared of 1D world. I need someone with the fortitude, skill and knowledge to deal with the monsters of the 3rd dimension! They can be scary for a 3D newbie!

Let me know if you find someone like that!
Then he (she?) can protect me too!
 
  • #38
You need a tesseract (Google has it) to travel between the dimensions.

:wink:
 
  • #39
Hehe, I know it ;) I saw Carl Sagan once explaining about it! :)

I'll scan my next attempt when I get home in a few hours, it's too long to rewrite with big black marker. Meanwhile I'm tackling other problems (*coughs* expect another thread *coughs*)^^
 
  • #41
Femme_physics said:
My By is different than yours, ILS, from some reason

You caught me!
Your answer is right.

That also means I made another mistake...
I'll leave it to you to find it! :smile:Btw, I didn't hear your *cough* in time. Perhaps next time! :wink:
 
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  • #42
I like Serena said:
You caught me!
Your answer is right.

That also means I made another mistake...
I'll leave it to you to find it! :smile:


Btw, I didn't hear your *cough* in time. Perhaps next time! :wink:

:approve:

:)

I'll try and solve it completely tomorrow morning. Thank you! :)
 
  • #43
Solved :) I don't have a scanner to show the entire way buuuuuuuuuuuuuut these are MY results:

Bx = 0
By = 10
Bz = 68
Ay = 65
Ax =24
Az = 8
T = 99

I'll probably scan the paper this evening if I feel there's need, but I reckon it's all true here :)
 
  • #44
Good morning Fp! Nice to see you again! :smile:

I see you found my missing mistake as well!
And you were quicker than I thought you would be!

Nice work! :smile:
 
  • #45
I like Serena said:
Good morning Fp! Nice to see you again! :smile:

I see you found my missing mistake as well!
And you were quicker than I thought you would be!

Nice work! :smile:

Undermining my velocity eh? tsk tsk tsk :wink::cool:

All made possible thanks to you :redface:

Edit: I'm sensing a smiley epidemic infecting me. Uh oh. :eek::frown:
 
  • #46
Femme_physics said:
Undermining my velocity eh? tsk tsk tsk :wink::cool:

All made possible thanks to you :redface:

Edit: I'm sensing a smiley epidemic infecting me. Uh oh. :eek::frown:

Uh, oh! :bugeye::shy: Is it :-p contagious? :redface:
 
  • #47
:rolleyes:

Apparently! :bugeye:

:shy::redface:
 
  • #48
Now that you are in a good mood from having conquered 3D vectors, perhaps you might like to think about

'The hairy ball theorem'

This basically states that you can't brush all the hairs on a tennis ball in the same direction.

:rolleyes:

Laugh if you like but it is an important but lighthearted statement about vector fields, which you will eventually (or even soon) come across.

The usual mathematical presentation makes them appear hugely difficult, and there ae many questions at PF. This approach makes them easy and accessible.

Either way vector fields are very important in engineering and applied physics.

go well
 
  • #49
This basically states that you can't brush all the hairs on a tennis ball in the same direction.

Says who?!? *orders a tennis ball and a brush from ebay!*

Just you wait.

Either way vector fields are very important in engineering and applied physics.

Vector fields sounds like a lot of vectors...

The usual mathematical presentation makes them appear hugely difficult, and there ae many questions at PF. This approach makes them easy and accessible.

Rather interesting, overall. I always like your extra feedback. Educational, inspiring, interesting. I wonder if I ever run into it in my studies.
 
  • #50
When you are brushing, imagine each hair is a little vector arrow. All the brushed hairs form a vector field.

On the tennis ball you will find that there is always (at least) one point where there is a change of direction.

We use vector fields when we do fluid mechanics, internal stress analysis, electric and magnetic field theory etc etc.
We imagine little vector arrows attached to each fluid particle or whatever and work out the overall effect they have (their vector sum).
 

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