Hardfire: Physics of 9/11

BigAl said:
The beams hit by the jets were boxes about 8 inches by 18 inches (from memory) made of steel six tenths of an inch thick.

The description of the machine in this video says that it can cut material up to 150mm (~6 inches) thick with a water jet.

WaterJet Cutting Machine In Operation on 3mm Stainless Steel
http://www.youtube.com/watch?v=sorgD9nhIQk​



The beams were not intended to take a local load in a horizontal direction. They folded like a cheap suit. A speeding car could to a pretty good job one.

(This is like talking to my cat.)
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You know wwhat they say Al...sleeping with prostitutes is like making your cat dance with you on her hind legs. You know it's wrong, but you try to convince yourself that she's enjoying it as well.
 
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The steel in the core was wide-flanges (an I in cross-section) and some built-up tubes. The exterior columns were built-up tubes.
 
bill smith said:
Al the columns were 14 x 14 . Are you sure about the six-tenths of an inch ?
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Give or take a tenth, yes.

The exterior beams were not square. Anyone that stood at a window saw that.

I'm fuzzy on the width and depth but when i saw the thickness documented, I was struck by it, too. I can't find a link to the publication it was in. Maybe someone else will chip in.

It was a paper that diagrammed all the masses in a 757 and attempted to calculate where all the momentum went as the body of the plane penetrated the "screen" of exterior columns. It went to some length to document the beam dimensions.


Bill, here's your aluminum cladding that you say you can't find enough of.

 
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BigAl said:
Give or take a tenth, yes.

The exterior beams were not square. Anyone that stood at a window saw that.

I'm fuzzy on the width and depth but when i saw the thickness documented, I was struck by it, too. I can't find a link to the publication it was in. Maybe someone else will chip in.

It was a paper that diagrammed all the masses in a 757 and attempted to calculate where all the momentum went as the body of the plane penetrated the "screen" of exterior columns. It went to some length to document the beam dimensions.


Bill, here's your aluminum cladding that you say you can't find enough of.

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Thanks. No it's not the cladding I have a problem with. It's a lot of the structural steel, the 5,000 floor pans and the 110 acres of rebar/wire mesh floor reinforcing that I have a problem with.Plus most of the concrete.
 
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Toke said:
The washer video was pretty jerky.
Your models show that mass distribution influence both swaying frequency and speed of collapse.

I am with you so far.

The problem comes when you draw conclutions from it.

You (or bill?) claim that the swaying from impact should have been obvius to the naked eye.
No, not enough swaying for that.

You claim that the collapse should/could have slowed down to a stop.
No, once it got moving there was no stopping it.
It would have taken something far stronger and more massive than the building to stop the drop, like the ground.

It looked like your washer model had a basic error.
The drop distance to first toothpick were higher than the distance between the rest of them. That means the tootpicks can be far too strong and you can still get the first few to break.
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If you listened to the audio I said that 20 washers dropped from 1 inch broke a toothpick one third of the time and dropped from two inches broke a toothpick 100% of the time.

If you ASSUME that it is possible for the top of the north tower to have crushed the rest of the building then what you say makes some degree of sense. But if you have to PROVE that it could then you have a problem.

But my objective was to show that STATIONARY MASS causes the falling mass to slow down in addition to the toothpicks. I have communicated with a number of people on other boards saying that the mass in the towers would just add to the falling mass and it would keep going and accelerating.

NOT POSSIBLE! The conservation of momentum would prevent it and the energy lost breaking and dislocating the supports would eventually stop the whole thing in the unlikely event that it did not fall down the side which is the more probable result.

So I got a MINIMUM of 15 broken toothpicks with no mass to support.

And a MAXIMUM of 9 broken with mass.

So I showed that mass slows the collapse down faster, it did not increase the destructive power. I was NEVER trying to make a scale model.

R. Mackey talking about making a scale model without talking about everyone knowing the distribution of steel and concrete in the towers is contradicting himself. Why are you talking about a scale for distance without talking about the mass I am working with. My stack of 20 washers is only 3.8 ounces.

Do you know the distributions of steel and concrete that were in the WTC. Because if you don't you are talking BS.

psik
 
bill smith said:
Thanks. No it's not he cladding I have a problem with. It's a lot of the structural steel, the 5,000 floor pans and the 110 acres of rebar/wire mesh floor reinforcing that I have a problem with.Plus most of the concrete.
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Problem solved HERE, with a little browsing. A truther site no less.

Thanks to Gravy's work for the link

BV
 
psikeyhackr said:
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If you listened to the audio I said that 20 washers dropped from 1 inch broke a toothpick one third of the time and dropped from two inches broke a toothpick 100% of the time.

If you ASSUME that it is possible for the top of the north tower to have crushed the rest of the building then what you say makes some degree of sense. But if you have to PROVE that it could then you have a problem.

But my objective was to show that STATIONARY MASS causes the falling mass to slow down in addition to the toothpicks. I have communicated with a number of people on other boards saying that the mass in the towers would just add to the falling mass and it would keep going and accelerating.

NOT POSSIBLE! The conservation of momentum would prevent it and the energy lost breaking and dislocating the supports would eventually stop the whole thing in the unlikely event that it did not fall down the side which is the more probable result.

So I got a MINIMUM of 15 broken toothpicks with no mass to support.

And a MAXIMUM of 9 broken with mass.

So I showed that mass slows the collapse down faster, it did not increase the destructive power. I was NEVER trying to make a scale model.

R. Mackey talking about making a scale model without talking about everyone knowing the distribution of steel and concrete in the towers is contradicting himself. Why are you talking about a scale for distance without talking about the mass I am working with. My stack of 20 washers is only 3.8 ounces.

Do you know the distributions of steel and concrete that were in the WTC. Because if you don't you are talking BS.

psik
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I've already done a conservation of mass study. The upper block continues to accelerate even with the conditions that are most favorable to collapse arrest.
 
NOT POSSIBLE! The conservation of momentum would prevent it and the energy lost breaking and dislocating the supports would eventually stop the whole thing in the unlikely event that it did not fall down the side which is the more probable result.
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The energy gained from gravity when the upper part drop a floor is alot higher than the energy lost breaking a floor, so no slowdown from that. And it grows with the amount of mass falling.

You should be aware that "conservation of momentum" is a tricky one and superseeded by "conservation of energy".
Conservation of momentum already deduct alot of energy going to losses in the collision, if you deduct it again you will get a wrong result.

I think you should make a horizontal model with dominoes and compare the results.
Try set them up in singles and doubles and see which one crosses the room first.

Like II II II II II II
and I I I I I I I I I I

I am looking forward to the video.
 
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Do not post other users private information, and that includes names that you may have found elsewhere. Please refer to other members by the names they use here unless it is clear that the other user has no objection.
Replying to this modbox in thread will be off topic  Posted By: Tricky
 
Tricky said:
Do not post other users private information, and that includes names that you may have found elsewhere. Please refer to other members by the names they use here unless it is clear that the other user has no objection.
Replying to this modbox in thread will be off topic  Posted By: Tricky
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you may want to check rule 8 again tricky. re: "not otherwise publicly available"

which it is

http://heiwaco.tripod.com/contact.htm

I mention this because I was warned in 06 regarding posting personal information for another engineer but my warning was rescinded when I had shown to the moderation staff via a pm that the engineer in question had already put his personal information out there on the web.
 
Toke said:
The energy gained from gravity when the upper part drop a floor is alot higher than the energy lost breaking a floor, so no slowdown from that. And it grows with the amount of mass falling.

You should be aware that "conservation of momentum" is a tricky one and superseeded by "conservation of energy".
Conservation of momentum already deduct alot of energy going to losses in the collision, if you deduct it again you will get a wrong result.

I think you should make a horizontal model with dominoes and compare the results.
Try set them up in singles and doubles and see which one crosses the room first.

Like II II II II II II
and I I I I I I I I I I

I am looking forward to the video.
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I am not wasting my time on dominoes.

No comment on your not knowing the distribution of mass in the WTC?

c. Determine the amount of kinetic energy lost due to the collision.
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http://www.mcbridehq.com/ClassHP/LAHS/APPhys/Handouts/3 - Momentum Wrapup.htm

I already computed a short gravitational collapse with conservation of momentum and demonstrated that mass variation affected time I didn't bother doing kinetic energy. But since there were no supporting forces to be overcome the collapse could not possibly stop.

http://the911forum.freeforums.org/post2501.html#p2501

No one has found a problem with it since last July when I first put it on Dawkin's site, but a lot of dummies have demonstrated that they did not understand it and declared it was irrelevant.

psik
 
No matter what brought the towers down the conservation of momentum cannot have been violated. This is the equation for an inelastic collision in which two masses stick together. If the second mass is stationary then v2 is zero.

Conservation of Momentum:

(m1 * v1) + (m2 * v2) = (m1 + m2) * v3
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So ten stories accelerate at 1G for one story, hit one floor, loose a small part of their speed, and 11 floors then accelerate at 1G for a distance of one story toward the next.

Or the 10 stories start at stationary, at the next floor they are slowed a bit but still moving. Next floor again the 11 stories have accelerated one floor more and are slowed a bit but still going faster than above.


The speed of falling would increase all the way down.
The speed of acceleration would also increase as the relationship between falling and stationary masses changes.
 
Toke said:
So ten stories accelerate at 1G for one story, hit one floor, loose a small part of their speed, and 11 floors then accelerate at 1G for a distance of one story toward the next.

Or the 10 stories start at stationary, at the next floor they are slowed a bit but still moving. Next floor again the 11 stories have accelerated one floor more and are slowed a bit but still going faster than above.

The speed of falling would increase all the way down.
The speed of acceleration would also increase as the relationship between falling and stationary masses changes.
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People keep talking about FLOORS and thinking about those square donut floor slabs. Didn't the CORE of the top 16 stories of the north tower have to come down on the CORE of the stationary portion below?

Suppose you had two boxes of Captain Crunch and you hold one in each hand with you arms spread as far as possible. Then you smash them together as hard as you can. Is the box in you left hand going to remain intact and crush the one in your right? Is the box in you right hand going to remain intact and crush the one in your left? NO! They are both going to get crushed. That is going to consume energy in both.

That is one thing wrong with my collapse of washers. My 20 falling washers are practically a solid mass and will not absorb any energy.

The was not the case in the WTC. For every level destroyed in the lower intact portion there would have to be one destroyed in the upper falling portion.

93 levels getting heavier and stronger going down vs 16 getting lighter and weaker going up. Which had to win? What other forces had to be involved for the bottom not to win?

How has this nonsense dragged on for SEVEN YEARS?

Where is that distribution of steel and concrete data (from an official source)?

psik
 
psikeyhackr said:
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People keep talking about FLOORS and thinking about those square donut floor slabs. Didn't the CORE of the top 16 stories of the north tower have to come down on the CORE of the stationary portion below?

Suppose you had two boxes of Captain Crunch and you hold one in each hand with you arms spread as far as possible. Then you smash them together as hard as you can. Is the box in you left hand going to remain intact and crush the one in your right? Is the box in you right hand going to remain intact and crush the one in your left? NO! They are both going to get crushed. That is going to consume energy in both.

That is one thing wrong with my collapse of washers. My 20 falling washers are practically a solid mass and will not absorb any energy.

The was not the case in the WTC. For every level destroyed in the lower intact portion there would have to be one destroyed in the upper falling portion.

93 levels getting heavier and stronger going down vs 16 getting lighter and weaker going up. Which had to win? What other forces had to be involved for the bottom not to win?

How has this nonsense dragged on for SEVEN YEARS?

Where is that distribution of steel and concrete data (from an official source)?

psik
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You're wrong on multiple levels, but this isn't the thread the place to discuss this topic.
 
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