Challenge: Demonstrate Sagging floor Trusses Pulling in Perimeter Columns

Grizzly Bear said:
It has to do with his post on page 8...
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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:
ozeco41 said:
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....
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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:
catsag1.jpg
The First Experiment "Does sideways pressure cause pull in AND how easy is it?
catsag2.jpg
A force of "one (smallish) 6yo push" - approx 500mm "sag" and ~100mm "column inwards displacement".

The Second Experiment
Inwards force applied directly to column.
catsag3.jpg
A force, also of "one (smallish) 6yo push" - directed inwards and applied directly to the column. "column inwards displacement" ~25 mm.
ozeco41 said:
So that is the principle proved.
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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.
 
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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'.
 
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.
 
jaydeehess said:
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.
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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.

jaydeehess said:
I would regard 400% as qualitatively 'very effective'.
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Point proved.
thumbup.gif
 
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ozeco41 said:
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.
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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...
 
jaydeehess said:
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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We "crossed in posting" :o

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"

:rolleyes:
 
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ozeco41 said:
We "crossed in posting" :o

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"

:rolleyes:
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True. There may also be issues with what 'I am helping grandpa' with by interfering parental units.:D
 
Newtons Bit said:
I guess we've seen the last of enik...
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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.
 
ozeco41 said:
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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He seems like a fellow that, once shown the correct concepts, could get himself out of teh "Truth".
 
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