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Old 8th August 2013, 11:06 AM   #401
beachnut
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Originally Posted by enik View Post
... Letís use the 35 foot truss from NIST NCSTAR 1-6B. This first scenario is a 1000 lb force on the top side of the truss at a modulus of elasticity of 30 x 106 psi.
... Here is the question, what is happening to the reaction forces?
You use NIST 1-6B, a full up model of the floor with fire protection. Makes your work useless for the task at hand. Any layperson can see your mistake. You use insulated data, for insulated reality. Is this special engineering for spreading the inside job? What is next, you failed this time, using the wrong data.
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Old 8th August 2013, 12:52 PM   #402
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Originally Posted by enik View Post
I apologize, my initial analysis did use a nylon rope, which was flexible. Let me change it to a steel rope that is already taut.
Attachment 28750

Now if we pull on the already taut steel rope, we get...

pull in of the columns because, we are pulling them in (I had to apply a magnification for clarity in the FEA results). Care to guess what happens if we double the load on the already taut steel rope?

So we agree that by pulling on steel columns with a steel (or taut) rope, we get pull in. Letís move back to your ďcentenary sag is a very effective force multiplierĒ.

Letís use the 35 foot truss from NIST NCSTAR 1-6B. This first scenario is a 1000 lb force on the top side of the truss at a modulus of elasticity of 30 x 106 psi.

The second scenario is the same force but with a modulus of elasticity of 8.7 x 106 psi.

And letís take that modulus down to 1.7 x 106 psi.

It may be a little difficult to see, but the displacement in the middle of the truss is increasing (I had to apply a magnification factor again for clarity)?

Here is the question, what is happening to the reaction forces?
Catenary behavior occurs when a member can no longer carry vertical forces purely through bending. To do this with a truss, you will need to remove a truss web member or two or push said members into a buckled state to generate catenary behavior.
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Old 8th August 2013, 04:26 PM   #403
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Originally Posted by Newtons Bit View Post
Catenary behavior occurs when a member can no longer carry vertical forces purely through bending. To do this with a truss, you will need to remove a truss web member or two or push said members into a buckled state to generate catenary behavior.
...or heat the truss.

You are quite correct about "catenary behavior" (my emphasis above). However the discussion between me and enik is not about catenary behaviour. It is a dispute one of the underlying factors.

My comment was correct. My "layman's explanations" prove that. So does your simple example.

enik's denials are false.

Sorry to appear pedantic BUT there is a false claim by Tony Sz still unresolved. In essence he claimed that catenary sag and bending resistance effects in the beam cannot co-exist. That is hogwash so I'm covering my arse in case Tony ever deigns to support his false claim. Rebutting the claim would be straightforward but I would need to go back to engineering basics given that the situation was outside the scope of normal engineering design parameters and the associated assumptions.

There is another point of engineering pedantry which may arise if ever I need to rebut that false claim by Tony. But I'll not confuse the current discussion by diverging.
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Old 8th August 2013, 04:46 PM   #404
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Originally Posted by ozeco41 View Post
...or heat the truss.

You are quite correct about "catenary behavior" (my emphasis above). However the discussion between me and enik is not about catenary behaviour. It is a dispute one of the underlying factors.

My comment was correct. My "layman's explanations" prove that. So does your simple example.

enik's denials are false.
In that case, you should have no problem with my question in Post 400.
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Old 8th August 2013, 04:48 PM   #405
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Originally Posted by Newtons Bit View Post
Catenary behavior occurs when a member can no longer carry vertical forces purely through bending. To do this with a truss, you will need to remove a truss web member or two or push said members into a buckled state to generate catenary behavior.
My question about the reaction forces should be a no-brainier for you. Right?
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Old 8th August 2013, 05:17 PM   #406
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Originally Posted by enik View Post
My question about the reaction forces should be a no-brainier for you. Right?
Yes, of course. Assuming that the truss has not yielded, there will be very little (or none, depending on the type of analysis) difference in reaction forces and that they are purely vertical.

The reaction forces for your steel cable example will be parallel to the cable direction (cables are tension only!) and the sum of the vertical reactions of both ends will be equal and opposite to the vertical load applied to the middle of the cable. (self-weight calculated otherwise)
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Last edited by Newtons Bit; 8th August 2013 at 05:22 PM.
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Old 8th August 2013, 06:23 PM   #407
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Originally Posted by enik View Post
In that case, you should have no problem with my question in Post 400.
True but I'm not going to follow your derail.

I have responded to your false claim that my comment to Tony Sz was wrong. It isn't. And I have rebutted in detail many of your false assertions. You have neither responded to those rebuttals nor posted your own claim about the subject of my original statement of a bit of simple physics. Your example is not about that "bit of simple physics". No matter how many times you shift the goalposts you will not fool me. Take that reality on board.

Sure I could follow your goalpost shift. Newton has in his post. His post is correct for the shifted scenario. It is simple basic engineering.

(Side Note: Any other members who may be unsure as to what is the goalpost shift either post the question or PM me. My previous posts give layman level explanations of the issue that enik has disagreed with. Those explanations of mine have not been addressed and certainly not rebutted by enik. Newton's posts, insofar as they overlap that issue, are fully supportive of my original claim. I have spent a lot of time clearly showing enik's bits of evasive dishonest trickery. I don't want to assit enik with the derailing tactics he is playing.)

Originally Posted by enik View Post
My question about the reaction forces should be a no-brainier for you any reasonably competent engineer. Right?
FTFY I can analyse your different scenario as readily as I analyse the one you falsely criticised. I won't at least before you respond reasonable to what I have said.

This post by Newton explains in words some of the same points of principle that I have explained in my previous posts BUT it applies to a different scenario:
Originally Posted by Newtons Bit View Post
Yes, of course. Assuming that the truss has not yielded, there will be very little (or none, depending on the type of analysis) difference in reaction forces and that they are purely vertical.

The reaction forces for your steel cable example will be parallel to the cable direction (cables are tension only!) and the sum of the vertical reactions of both ends will be equal and opposite to the vertical load applied to the middle of the cable. (self-weight calculated otherwise)
...every point agreed....within that scenario.
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Old 8th August 2013, 07:36 PM   #408
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Originally Posted by Dcdrac View Post
it seems Tony although I am no structural engineer by an stretch, that your points have been answered and shown to be incorrect by people who are structural engineers.

I have learnt a fair bit from them but what I have learnt from you is you do not seem to know when to accept defeat.
It would seem to me that you still have a lot to learn. Who would be the structural engineers you mention?
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Old 8th August 2013, 07:57 PM   #409
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Old 9th August 2013, 06:27 AM   #410
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Originally Posted by ozeco41 View Post
...or heat the truss.

You are quite correct about "catenary behavior" (my emphasis above). However the discussion between me and enik is not about catenary behaviour. It is a dispute one of the underlying factors.

My comment was correct. My "layman's explanations" prove that. So does your simple example.

enik's denials are false.

Sorry to appear pedantic BUT there is a false claim by Tony Sz still unresolved. In essence he claimed that catenary sag and bending resistance effects in the beam cannot co-exist. That is hogwash so I'm covering my arse in case Tony ever deigns to support his false claim. Rebutting the claim would be straightforward but I would need to go back to engineering basics given that the situation was outside the scope of normal engineering design parameters and the associated assumptions.

There is another point of engineering pedantry which may arise if ever I need to rebut that false claim by Tony. But I'll not confuse the current discussion by diverging.
I'm quite confused as to what your and enik's dispute is about now.
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Old 9th August 2013, 06:35 AM   #411
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Two questions Tony.

1. How do you derive the bolded/red statement you make below...
Originally Posted by Tony Szamboti View Post
This is why John Skilling was able to say the Twin Towers could have one exterior face and its corners completely removed and be missing half the columns from the two normal side walls and the building could still take a 100 mph wind.
...from the bolded/red statement below?
Originally Posted by Tony Szamboti View Post
For those who need a citation to John Skilling's comment about the strength of the perimeter walls, Glanz and Lipton mention it in their book City in the Sky.

The Vierendeel trusses would be so effective, according to the engineers' calculations, that all the columns on one side of a tower could be cut, as well as the two corners and several columns on the adjacent sides, and the tower would still be strong enough to withstand a 100-mile-per-hour wind. --City in the Sky, p 133

How do you get "half the columns for the two sides (meaning 28 from one side and 28 from the other) from "several columns from the adjacent sides"?

2. Is the quote from the book that you reference being made by Skilling himself or the authors? I don't see quote marks or a reference to Skilling saying that.
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Old 9th August 2013, 07:42 AM   #412
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Originally Posted by Newtons Bit View Post
I'm quite confused as to what your and enik's dispute is about now.
It is a denial by enik of a simple fact of physics which I stated as an explanatory comment to Tony Szamboti.

It arose whilst Tony was in debate with femr2 and Tony claimed that enik had "proved" something.

My recollection was that Tony was claiming more than had in fact been "proved". That discussion led to me making this comment to Tony SZ:
Originally Posted by ozeco41 View Post
I am relying on memory - haven't researched historic posts.....[BUT for your "could not"]...... to be correct it would require catenary sag to not produce enough force to bend the columns. I don't recall that being shown...I could be wrong. But catenary sag is a very effective force multiplier....
So my claim was one of basic physics - "catenary sag is a very effective force multiplier" - the apparent limit to "catenary" arose from the discussion. The principle however is not confined to catenary. Any "taut rope pushed sideways" will exert a pull in force on the end attachments that is much larger than the applied "push sideways force". You proved the generic point with a specific example back a couple of posts with this part of your drawing:


Your example shows ~45 kip "pull in" for 1 kip applied sideways force. (near enough - T is not the actual horizontal vector but the angle is small)

That simple fact of physics is all that I relied on in my original explanation for Tony. And Tony accepted that aspect without question.

Whatever his agenda enik is persisting in trying to prove me wrong by changing the scenario/assumptions/ whatever. I have presented explanations at very simple lay person level. Enik true to his style ignores my explanations and tries to change the subject. I won't fall for it.

Hence my extreme care to agree with what you correctly stated in each of your recent posts BUT noting that your examples were from a different scenario.

Last edited by ozeco41; 9th August 2013 at 07:45 AM. Reason: spelling
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Old 9th August 2013, 08:07 AM   #413
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The way I understand the "ozeco41 vs. enik catenary sag" debate...

Quote from Tony...
Originally Posted by Tony Szamboti View Post
Enik showed that the trusses and floors by themselves could not generate enough force to pull in and cause buckling of the perimeter columns, although they could transmit the force generated by downward moving outer core columns which were fully capable of generating the required force.

Quote from ozeco41 in response to Tony's quote above...
Originally Posted by ozeco41 View Post
I am relying on memory - haven't researched historic posts because the issue is minor - I recall several discussions and the problem that sometimes besets FEA work of assumed contexts which do not match reality.

Then, at first examination I do not see how the two options you identify "could not generate" BUT "could transmit" can be correct. The "could transmit" almost certainly correct - masses of force from core column sinking >>> plenty of tensile strength in joists >>>enough to bend perimeter cols. So for "could not generate" to be correct it would require catenary sag to not produce enough force to bend the columns. I don't recall that being shown...I could be wrong. But catenary sag is a very effective force multiplier. If "could not generate" is in fact claimed my interest in the rationale (and the numbers) could be aroused.

EXCEPT that the issue is moot unless it is needed to resolve the discussion you v femr2.

Nevertheless I may do some post archaeology.
As I understand it, ozeco41 is saying that catenary sag is an effective force multiplier and that he did not recall it being shown anywhere the catenary sag cold NOT produce enough force to bend the columns.

enik then quoted this part of ozeco41's quote above...
Originally Posted by ozeco41 View Post
...But catenary sag is a very effective force multiplier.

...and then stated this...
Originally Posted by enik View Post
You will need to provide some calculations to further this argument.
So, based on ozeco41's latest post above, he provided calculations that show that "catenary sag is an effective force multiplier.

The question I have is this. Was enik asking for calculations showing basic catenary sag (as provided by ozeco41 above) or was enik asking for calculations showing how the catenary sag affected the columns? If it is the latter, then enik is asking for the same thing that ozeco41 said he doesn't remember seeing.

Am I getting this right?

Last edited by Gamolon; 9th August 2013 at 08:08 AM.
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Old 9th August 2013, 08:36 AM   #414
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Originally Posted by Gamolon View Post
The way I understand the "ozeco41 vs. enik catenary sag" debate...

[Context described correctly by Gamolon] ...
...
Yes
Originally Posted by Gamolon View Post
As I understand it, ozeco41 is saying that catenary sag is an effective force multiplier and that he did not recall it being shown anywhere the catenary sag cold NOT produce enough force to bend the columns...
Correct but those are two separate points. Three if the lawyer in me gets legally pedantic.

A) The first one "catenary sag is an effective force multiplier" is a simple fact of applied physics - a "truism". That is where enik is saying I am wrong and moving goalposts all over the planet to try to sucker me into a different argument. I'm not falling for it.

B) The second one - legal pedantry - "that he did not recall it being shown anywhere" was true - at the time I could not remember.

C) The third one "the catenary sag could NOT produce enough force to bend the columns.." is more complicated. Believe it or not it is NOT the topic of the current discussion. It should be because it is the OP for this thread but.... Leave it for now.

Originally Posted by Gamolon View Post
...enik then quoted this part of ozeco41's quote above...

...and then stated this...
Quote:
You will need to provide some calculations to further this argument.
Correct. But the point did not need calculations and calling for unnecessary calculations is a standard evasion trick played by enik (and Tony Sz)

Originally Posted by Gamolon View Post
...So, based on ozeco41's latest post above, he provided calculations that show that "catenary sag is an effective force multiplier...
Yes - mea culpa. I compromised my tough stand. The problem was that I had to do a trade off. There were lay persons reading and some posting on the topic. enik was trying to fool them. He knows that he won't fool me so I posted the "lay persons explanations" so he has less chance of fooling the lurkers -- with near zero calculations but ...I put some very simple ones in. BTW enik wont count them - they are not FEA.

However Newtons bit also posted some more engineering looking calcs.....
Originally Posted by Gamolon View Post
...The question I have is this. Was enik asking for calculations showing basic catenary sag (as provided by ozeco41 above) or was enik asking for calculations showing how the catenary sag affected the columns? If it is the latter, then enik is asking for the same thing that ozeco41 said he doesn't remember seeing....
Yes - and remember that "what I don't remember seeing" is a actually "what I DIDN'T remember seeing" at the time I made the comment. I've since done the extensive post archaeology. Here and across on 911Forum. It doesn't help. It is just as vague and foggy as most of enik's posts. But I'm 90% sure enik didn't prove what he and Tony Sz claim he did prove. BUT that discussion can wait until we get back to the actual original real OP topic of this thread. If that miracle ever eventuates.

Originally Posted by Gamolon View Post
...Am I getting this right?
Actually even I'm getting confused. BUT will you accept "I think so?"
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Old 9th August 2013, 08:44 AM   #415
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Originally Posted by ozeco41 View Post
Actually even I'm getting confused. BUT will you accept "I think so?"
Absolutely!

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Old 9th August 2013, 09:11 AM   #416
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Originally Posted by Gamolon View Post
Absolutely!

Thank you.

The current disagreement with enik is his evasion tactic - the issue of physics is without doubt. Waste of bandwidth discussing further.

The complexity is with the OP of this thread. And I'm not going there unless the original protagonists re-open discussion AND both sides make errors which need correction.

Let's hope it dies a natural death.

Cheers.
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Old 9th August 2013, 09:52 AM   #417
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Originally Posted by Newtons Bit View Post
Yes, of course. Assuming that the truss has not yielded, there will be very little (or none, depending on the type of analysis) difference in reaction forces and that they are purely vertical.
Yes. Too bad Ozeco41 didn't answer up similiarly.
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Old 9th August 2013, 10:20 AM   #418
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Originally Posted by enik View Post
Yes. Too bad Ozeco41 didn't answer up similiarly.
similarly, Too bad? How does this tie in to the inside job claims you have made, the CD fantasy? How did you put it it? "Inside Job Evidence is in the Physics of WTC #1". Does this stand in your fantasy inside job? How does the failed FEA you have support your Inside Job Evidence?

Where is your paper published, or letter, refuting Usmani's work? https://www.era.lib.ed.ac.uk/bitstre...1/WTCpaper.pdf What did Usmani say about your effort? Your challenge was beat up before it was posted. Is that moving the goal post to exclude Usmani, wave your hands declare some BS stuff, etc? The paper is published where? Your Pulitzer Prize winning inside job evidence, with the help of Physics, is published where? Why have zero newspapers grabbed your outstanding work and got the Pulitzer? Watergate was big Pulitzer material, why is 911 truth inside job CD stuff not making the grade? Will this work push you into the Pulitzer race with your local Newspaper? If I knew 911 was an Inside Job and I proved NIST was wrong on the Sagging floor, I would have nothing... lol

How does NIST 1-6B fit with your no insulation analysis? Explain in detail. Is this work going to be your thesis?

Last edited by beachnut; 9th August 2013 at 10:26 AM.
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Old 9th August 2013, 10:39 AM   #419
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Originally Posted by enik View Post
Yes. Too bad Ozeco41 didn't answer up similiarly.
What was your point behind that question?
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Old 9th August 2013, 07:52 PM   #420
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Originally Posted by Newtons Bit View Post
What was your point behind that question?
It has to do with his post on page 8, basically being in disagreement with the NIST report on a single element which he though was relevant to what Ozeco was talking about in the Tony Szamboti new publication thread.

Which doesn't make such sense to me... the section he was referencing mentions several different factors working in tandem and the impression I get is that he's centering all his criticism around that single one point of interest... along with the whole strong holding of using FEA measurements absolutely...

And I've yet to figure out what the implications are supposed to be, if running under the assumption the question he raises is valid...
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Old 10th August 2013, 12:19 AM   #421
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Originally Posted by Grizzly Bear View Post
It has to do with his post on page 8...
Whilst your comments are true the original issue was much simpler. In the enik post you refer to enik is already well away from the question he is evading.

I made an offer in this post:
Originally Posted by ozeco41 View Post
If I put it down to 10 year old understanding level:Step One: The Principle. Fix a rope tightly between two trees. Lean sideways on the middle of the rope. The force pulling the trees together is a lot bigger than the force you applied. That is the ten year old bit. If this nonsense continues I may try it on my six year old grandson and see if he agrees. Then take photos and post them....
Well a surprise visit from 6yo grandson happened at short notice so here are the photos to show that a 6yo can understand the simple principle I stated and enik disputes:

The Experimental Set-up. A rope stretched taut between two columns:
The First Experiment "Does sideways pressure cause pull in AND how easy is it?
A force of "one (smallish) 6yo push" - approx 500mm "sag" and ~100mm "column inwards displacement".

The Second Experiment
Inwards force applied directly to column.
A force, also of "one (smallish) 6yo push" - directed inwards and applied directly to the column. "column inwards displacement" ~25 mm.
Originally Posted by ozeco41 View Post
So that is the principle proved.
Some comments from the post experiment interview of the performer. Excuse the leading questions.
Q1 Grandpa: Which was easier - pushing the rope or pushing the tree.
A1 Grandson: "Pushing the rope" (Note the language concession of "tree" rather than "column". IMO justified given the age and vocabulary of the performer.)
Q2 Grandpa: Why was it easier?
A2 Grandson: "The rope makes it easier." Note the direct to the objective perception of that answer.

Several other Q & A's not needed.
The two "pushes" were calibrated by the specification "Push as hard as you can" in each case and audiometric judgement of similar levels of vocalised grunting from the performer.

I rest my case.
1) I was right; AND
2) A six year old understands the relevant point.

Last edited by ozeco41; 10th August 2013 at 02:05 AM. Reason: removed an ambiguity
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Old 10th August 2013, 01:13 PM   #422
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That is 100mm displacement of the column on the right, or only the total displacement of both? I assume the former. In which case the same force quantity applied to the rope as directly to the column is obviously 4 times as 'effective' at displacing the column. I would regard 400% as qualitatively 'very effective'.
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Old 10th August 2013, 01:24 PM   #423
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Suggestion for changing rope deflection to vertical:

Young lad sits on rope in first part of experiment. Measure deflection.

Second run has another two ropes, these are anchored just below existing rope. They are then run half way between columns at which point it is threaded over a simple pulleys. Young lad now grabs the ropes and is suspended by the. Measure deflection.
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Old 10th August 2013, 01:29 PM   #424
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Originally Posted by jaydeehess View Post
That is 100mm displacement of the column on the right, or only the total displacement of both? I assume the former. In which case the same force quantity applied to the rope as directly to the column is obviously 4 times as 'effective' at displacing the column.
The displacements were for the column on the right - the column on the left had larger cross section and was significantly more resistant to bending moment.

My choice of columns was limited - those are two outside my front door.

Originally Posted by jaydeehess View Post
I would regard 400% as qualitatively 'very effective'.
Point proved.

Last edited by ozeco41; 10th August 2013 at 02:05 PM.
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Old 10th August 2013, 01:36 PM   #425
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Originally Posted by ozeco41 View Post
Whilst your comments are true the original issue was much simpler. In the enik post you refer to enik is already well away from the question he is evading.
I was talking about the more recent discussions obviously... the OP and the original challenge though boils down to the same problem. I really have no problem with him having a disagreement, but narrowing the scope to the extreme and not outlining the consequences of such thinking is in my mind his fatal mistake, not the actual experiment or the challenge. As you fully know... little mistakes grow exponentially the more dependent conclusions and data are on the assumptions.


In effect... I actually think the matter is even simpler than you argue...
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Old 10th August 2013, 01:41 PM   #426
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Originally Posted by jaydeehess View Post
Suggestion for changing rope deflection to vertical:

Young lad sits on rope in first part of experiment. Measure deflection.

Second run has another two ropes, these are anchored just below existing rope. They are then run half way between columns at which point it is threaded over a simple pulleys. Young lad now grabs the ropes and is suspended by the. Measure deflection.
We "crossed in posting"

Those are reasonable options for further study BUT my purpose is already achieved -- my two claims demonstrated:
1) "sag is a very effective force multiplier" ("catenary sag" is a valid sub set of "sag") AND
2) A six year old boy understands which one moves the column easier - which fact is validly stated technically as "is a very effective force multiplier"


Last edited by ozeco41; 10th August 2013 at 01:47 PM. Reason: Punctuation
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Old 10th August 2013, 01:45 PM   #427
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Originally Posted by Grizzly Bear View Post
I was talking about the more recent discussions obviously...
Understood.
Originally Posted by Grizzly Bear View Post
..In effect... I actually think the matter is even simpler than you argue...
Agreed - the simple technical issue didn't need any argument.
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Old 10th August 2013, 02:09 PM   #428
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Originally Posted by ozeco41 View Post
We "crossed in posting"

Those are reasonable options for further study BUT my purpose is already achieved -- my two claims demonstrated:
1) "sag is a very effective force multiplier" ("catenary sag" is a valid sub set of "sag") AND
2) A six year old boy understands which one moves the column easier - which fact is validly stated technically as "is a very effective force multiplier"

True. There may also be issues with what 'I am helping grandpa' with by interfering parental units.
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Old 10th August 2013, 02:26 PM   #429
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Originally Posted by jaydeehess View Post
True. There may also be issues with what 'I am helping grandpa' with by interfering parental units.
Sure - but the whole episode relied on Family Entertainment Arrangements.


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Old 3rd February 2014, 09:56 PM   #430
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I guess we've seen the last of enik...
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Old 4th February 2014, 12:00 AM   #431
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Originally Posted by Newtons Bit View Post
I guess we've seen the last of enik...
Some months back he announced on The911Forum that he was withdrawing from intensive 9/11 discussion. Since he regards that forum as "home" I would expect that he doesn't see any need to announce anything here which he would regard as "enemy territory"

That said - after he had abused me over some issues here we took the discussion over to 911Forum and reached a more or less amicable agreement that I had been right on the central issue of our three way discussion here.

I give him high marks for being willing to do that.
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Old 4th February 2014, 08:19 AM   #432
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Originally Posted by ozeco41 View Post
Some months back he announced on The911Forum that he was withdrawing from intensive 9/11 discussion. Since he regards that forum as "home" I would expect that he doesn't see any need to announce anything here which he would regard as "enemy territory"

That said - after he had abused me over some issues here we took the discussion over to 911Forum and reached a more or less amicable agreement that I had been right on the central issue of our three way discussion here.

I give him high marks for being willing to do that.
He seems like a fellow that, once shown the correct concepts, could get himself out of teh "Truth".
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Old 4th February 2014, 07:37 PM   #433
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Originally Posted by Newtons Bit View Post
He seems like a fellow that, once shown the correct concepts, could get himself out of teh "Truth".
Yes.
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