9/11 Physics from Non-Experts

[Furcifer]

Sorry, my bad, not even 1 second. I don't have this spread sheeted, but the time to impact the second floor is only increased by 0.16s, and this is assuming the same "impact energy to collapse one floor" and only 1 story (3.7m) of initial collapse. Since the 6.29ee8 J would also be scaled down by the reduced mass, i think the overall collapse time would remain within the margins of error already established.

 

[beachnut]

So you don't want to talk about the live eyewitnesses captured on videotape.

So you are just a regular truther, sounds like an explosion, must be?

The better question what is wrong with this video. Are you able to do youTube?

http://www.youtube.com/watch?v=sBfkAzWbnvM

About witnesses, we have witnesses, thousands, none of them heard RDX, or CD cutter charges, as Jones puts it, on 9/11. Nice try, but sounding like and being are two different things. And this has been discussed and debunked so much. Find something new, something with some real evidence, not hearsay stuff. (skip the Dan Rather and other on the spot junk, I was watching TV on 9/11, Dan and the rest sounded as dumb as the truthers sound now)

It was a gravity collapse from steel failing in fire. Anyone who thinks steel is some super never failing stuff, only has to see one steel frame fire. Without fire protection steel will fail faster than wood. Sorry but you should study up on things. You could 20 or 30 years behind in experience on 9/11.

 

[beachnut]

Was there no pulverization of concrete? Or was there some pulverization of concrete? How much? Have you seen any photos from gound zero. Everything is buried in essentially sand. These photos outnumber the ones with any substantial pieces of concrete by 100 to 1 based on the 1000s of photos I have seen. Lets see your evidence! Links please.

Let me see your thousands of photo by time, collapse plus 1 minute. Let me see photos with dates on them. Most the truther photos are during the clean up. Yes Virginia, that is drywall dust on the ground, have you worked with dry wall before, it gets everywhere. Plus I see large chunks, I saw them everywhere.

So go ahead how much explosives would it take to do 9/11. Since the towers alone had the energy of 100 to 250 tons of TNT energy in each tower, what is missing to make a mess of the WTC complex. I will make you day how much energy do we need?

Still not one sound of CD explosions on 9/11. Why did the people I have talked to who saw both planes hit, miss the sound of CD? Why is you hearsay junk proof, when the witnesses I talk to say different, and why are those people not in the truth movement who the truth movement have quote mined to death. The same old stuff. Get some new material you have been debunked, look it up.

You have no line of photos by date. I have a floors fused together by the fall, just pressed together that Jones says are molten metal. Jones is a liar, why not correct his work first? Better add the glass to your mass of the WTC. Do not forget the water.

Back to thread topic what do you think about the video?

http://www.youtube.com/watch?v=sBfkAzWbnvM this one?

 

[Newtons Bit]

Thanks Newtons, that's what I used 25 psf. I was just trying to justify it for the other guys.

My deadload includes everything you mention except the exterior wall. The mass of the exterior wall is mostly the steel external column assemblies which are alread accounted for. I just compared the weight of the external column assemblies to the weight of aluminum cladding and windos and decided to ignore it. It would be more accurate to include it but it won't change my result much.

The wall is not an insignificant mass. There's many different components, and I can guarentee you that it weighs at least 10psf. Assuming it does, that's a grand total of 12000kips, not trivial. 6000 tons or whatever you guys work in (sheesh!)

 

[beachnut]

Sorry, my bad, not even 1 second. I don't have this spread sheeted, but the time to impact the second floor is only increased by 0.16s, and this is assuming the same "impact energy to collapse one floor" and only 1 story (3.7m) of initial collapse. Since the 6.29ee8 J would also be scaled down by the reduced mass, i think the overall collapse time would remain within the margins of error already established.

You must stop using that sigma stuff

 

[gumboot]

No offence, but these totals suck. 25lb for a computer?

I just weighed by old 17" CRT monitor and it alone came to 35lbs.

How much paper was there in the WTC? I have no idea, but I imagine it was a lot. Paper is heavy. Hundreds of offices, all with their paper records stacked away nice and neat. Boxes and boxes of fresh paper at every photocopier and printer.

One thing to consider when looking at live load design spec is that live loads have increased a lot since the early 1970's when the towers were built.

To begin with average office building occupant density has tripled. Secondly, individual office items has greatly increased.

Back in the 70's you might have one enormous office computer, if you really needed it. You'd have a typing department, that did all the typing for everyone on typewriters. Most people would be working at their desks with pen and paper.

Also, companies have to keep paper records normally, even in this high-tech age. In fact, anyone who has worked in offices for a long time will tell you that the arrival of the PC has actually INCREASED paper work. And all of that paperwork has to be filed away and stored. For some companies in the towers that could be decades and decades worth of paper work.

These days, you've got 3x as many people, everyone has at least one computer, you've got big heavy printers/photocopiers, big heavy data storage banks (and the massive air conditioning units you need to keep them cool!). You're going to need vastly more paper handy to supply all of your office's dozens of printers and copiers. You've got the added weight of all those Audio-Visual facilities modern offices have - televisions, VCRs, DVD players, projectors, and so forth, all the additional electronics required for networking the 200+ PCs on every floor, the list goes on.

The fact that tenants had to have parts of the building structurally reinforced for their specific purposes indicates quite clearly that the safety factor was insufficient to support the live load.

-Gumboot

 

[Furcifer]

You must stop using that sigma stuff

Yes I know, this is more of an integration than anything else

 

[gumboot]

Was there no pulverization of concrete? Or was there some pulverization of concrete? How much? Have you seen any photos from gound zero. Everything is buried in essentially sand.

It's not sand, it's dust. Most of it isn't concrete.

-Gumboot

 

[Furcifer]

Yes Virginia, that is drywall dust on the ground, have you worked with dry wall before, it gets everywhere. Plus I see large chunks, I saw them everywhere.
So go ahead how much explosives would it take to do 9/11. Since the towers alone had the energy of 100 to 250 tons of TNT energy in each tower, what is missing to make a mess of the WTC complex. I will make you day how much energy do we need?

These are two VERY good points. I never understood the "dustification" argument. As beachnut has pointed out, if you look at drywall/gypsum the wrong way it turns to dust. Let alone smash it with the force of 20 tons of TNT every second for 10 seconds. Which leads to his final point, how much explosive do you need to accomplish the "truther" goal? The video evidence clearly shows the building was not "dustified" in front of the collapse wave, but if we are to believe the conspiracy, we need to believe it was, which requires a god awful amount of explosives,which would have certainly "smushified" the people found in the lower levels after the collpase!

 

[gumboot]

I worked at a garden centre for a while, and we sold a lot of gypsum (it's excellent for breaking up clay soil, and Auckland is all clay). As a result I spent a lot of time offloading and packing away big bags of gypsum.

I can personally attest to its weight and how a very small amount can spread over a very large area.

-Gumboot

 

[SYLVESTER1592]

Still waiting

This is all very academical. We are going to recalculate the weight. Great, of course with an agenda… Now instead of looking at the data of the materials used as described by others (for instance Fernandez at MIT), we are going to estimate and calculate. I still have not seen an answer to my question and opposed to Mackey, I think it is relevant. The reason for the question is that the debris corresponds with the amount of material that went into building the towers. An exaggeration would be noticed immediately. J.E. Fernandez writes: “The material expenditures on the towers were enormous; 192,000 tons of steel, 425,000 cubic yards of concrete, 43,600 windows with 572,000 square feet of glass, 1,143,000 square feet of aluminum sheet, 198 miles of ductwork and 12,000 miles of electrical cable.” http://web.mit.edu/civenv/wtc/PDFfiles/Chapter I History.pdf Even when we assume much of this weight is not above ground, I question whether these numbers were considered in the calculations. Others in this thread have already called attention to the interior of the building, so I won’t repeat that discussion. Now steel and floor surfaces and elevators and such are one thing, but this summation of materials and the earlier stated amount of debris do not permit me to follow the conclusions of Mr. Urich, despite his calculations. At least the question stands. If your calculations are right, where did all the material go… I have asked nicely, but do expect a satisfying answer, no answer means no defense and in my opinion prompt rejection of your conclusions. You do realize... Anyone else, buying into this because the math works would still end up with this problem. My only conclusion at this moment in time is that an explanation that explains the massive amount of debris and the massive amount of building materials used for the construction, must be given and fitted to Urichs calculations, in order to make Urichs calculations acceptable. I’m not an engineer or great physicist, but mass does not disappear and reappear in conventional mechanics as far as I know (except maybe when you are S. Jones and work on cold fusion using muons, but I would have to look into that closer when time permits). Maybe I'm still confused...Still waiting patiently… Sincerily, SYL

 

[TellyKNeasuss]

For those who are interested, my article is at:

...journalof911studies.com/letters/wtc_mass_and_energy.pdf

I've seen several claims that each tower had 212,500 cubic yards of concrete in it. Your paper implies, if I did the arithmetic correctly (not guarenteed, considering the state of my checkbook) that each tower had about 65,000 cubic yards of concrete. Any ideas on why such a large difference?

 

[gumboot]

The Empire State Building is estimated at nearly half again what GregoryUrich came up with for one WTC tower.

Yet each WTC tower had almost double the floor area. Explain.

-Gumboot

 

[gumboot]

I've seen several claims that each tower had 212,500 cubic yards of concrete in it. Your paper implies, if I did the arithmetic correctly (not guarenteed, considering the state of my checkbook) that each tower had about 65,000 cubic yards of concrete. Any ideas on why such a large difference?

I got 34,000 cubic yards of concrete just for the floors. On top of that there's the stairwells.

-Gumboot

 

[jaydeehess]

These are two VERY good points. I never understood the "dustification" argument. As beachnut has pointed out, if you look at drywall/gypsum the wrong way it turns to dust. Let alone smash it with the force of 20 tons of TNT every second for 10 seconds. Which leads to his final point, how much explosive do you need to accomplish the "truther" goal? The video evidence clearly shows the building was not "dustified" in front of the collapse wave, but if we are to believe the conspiracy, we need to believe it was, which requires a god awful amount of explosives,which would have certainly "smushified" the people found in the lower levels after the collpase!

The amount of explosive is only part of the problem.
One could calculate the energy required to pulverise 50% or 90% of the concrete flooring and equate that to x amount of a certain type of explosive. However, the placement of said explosives would then have to be 100% efficient in transferring its energy into pulverising the concrete. Even approaching that level of efficiency would absolutely require that the explosives be installed within the concrete and distributed widely throughout it on all floors. All of this would exacerbate the already complicated and vastly unneccessary nature of such a plot.

Simply put, even in a conspiracy to cause the collapse of these structures there is no reason to also require the pulverisation of the concrete flooring.

In the real world I can take a 16 oz. hammer to the sidewalk outside and each blow will raise a tiny bit of dust from the concrete. Breaking any amount of concrete will release dust. Add into the 110 storey, high speed, rock tumbler, 500,000 square feet of relatively fragile drywall (a very low ball estimate) and you end up with a hell of a lot of dust.

 

[jaydeehess]

I got 34,000 cubic yards of concrete just for the floors. On top of that there's the stairwells.

-Gumboot

I believe that many of the totals include the concrete that made up the basement walls. This need not be considered at all in any estimation of falling mass or of pulverised concrete.

 

[Furcifer]

The amount of explosive is only part of the problem.
One could calculate the energy required to pulverise 50% or 90% of the concrete flooring and equate that to x amount of a certain type of explosive. However, the placement of said explosives would then have to be 100% efficient in transferring its energy into pulverising the concrete.

Another very good point. Basically the only way to accomplish this would be to strip the walls and replace them with some sort of "explosive" drywall. And then there is the issue of making it happen sequentially. Oh, and making sure the "explosive drywall" was installed only on the floors below the impact point. I'm not trying to be a donkey about this either, i'm just trying to apply some logic .

 

[R.Mackey]

Let me put this to bed

I still have not seen an answer to my question and opposed to Mackey, I think it is relevant. The reason for the question is that the debris corresponds with the amount of material that went into building the towers.

I agree that this is a valid question -- sorry if I gave the alternate impression. The amount of debris trucked away should give a pretty good estimate, if not perhaps the best, of how much material there actually was.

Anyway, for Gregory Urich, two things.

First, I apologize for misspelling your name a few times. I don't know how that "L" got in there. Perhaps the "L" key on my keyboard is demanding equal time, or maybe the NWO is trying to send me a subliminal message to execute Plan L, I don't know. In any case, it was careless of me.

Second, in a previous post I identified several sources of error in your calculation. I don't know what the real answer is, of course, because as you correctly note, there is no readily available work that rigorously estimates the tower mass. However, there is an alternate tack, namely that of reductio ad absurdum.

Consider the following: Using your table from Page 4, let us consider your estimate binned into two fractions -- the total that is structural, and the total that is not. The latter total will include all live loads and all dead but non-structural loads, superimposed or fixed.

Following your calculations, we find that the structural load only, containing structural steel and concrete, totals to 159,135 metric tons, while the nonstructural load is 58,536 metric tons. Or, if we prefer archaic units, 175,416 short tons versus 64,525 short tons.

Now let's consider the total tower area. Each WTC tower had 110 floors (neglecting the sublevels, since it isn't quite clear whether to include them or not) each of 63.4 meters on a side. This totals to 442,151 m², or 4,759,040 ft² in caveman speech.

Let's suppose we're all in agreement with the structural figures, and only consider the remainder. Everything besides the bare steel and concrete flooring works out to 96 kg / m², or if you prefer, 27 lb / ft².

That's everything. That total includes windows, window washing equipment, drywall, floor tile, roofing, ceilings, fire insulation, stairwells, interior walls, carpeting, telephone and electrical wires, junction boxes, circuit breakers, lighting, data lines, plumbing, drinking fountains, toilets and sinks, emergency sprinklers, fire extinguishers and hoses, janitorial and supply cabinets, doors, Westinghouse cubicles, desks, workstations, mainframes, false flooring, copy machines, file cabinets, backup generators and UPS systems, tables, chairs, televisions, microwaves, refrigerators, projectors, air conditioners and heaters, ducting, intercoms, elevators and counterweights, trash cans, paint, pictures, office plants, and of course people, with all of their luggage, clothing, and accessories.

All that, in 96 kg / m².

Is this credible? No. We have several architects and structural engineers who will attest to this. Or, if you prefer instant gratification, here is a quick collection of city requirements, showing that the live load alone exceeds your calculation, by at least 150% in each case. And many of the items above don't even count as live load.

Look at this another way: Suppose all of your figures are correct. This structure of yours, 217,671 metric tons all told, is 73% load bearing structure. 73%!! Not very efficient use of concrete and steel, is it? If you were designing a building, and told your customer that for every single kilogram of contents you would need 3.74 kilograms of structure, do you think you'd win the contract?

Or perhaps a third way: Suppose you treated the WTC towers as a giant warehouse, in which you stored plywood. How much could it handle? Well, it would only accept 96 kg / m² of load, and using an optimistic figure of 500 kg / m³ of plywood... you'd only be able to stack it 19 centimeters high before the building couldn't take any more. Absurd.

It should be obvious by now that nobody would build such a structure. It would be an enormous waste of money.

In closing, again I note that a careful accounting of the true WTC mass is going to be a difficult and complicated undertaking. I don't know if the true mass was closer to 400,000 or 500,000 metric tons per tower. But there's no way that your figure, a mere 217,671 tons, has any bearing on reality. You wind up with a structure that is totally off balance with respect to efficiency, and the WTC Towers were among the most efficient buildings ever constructed.

If you truly are here in search of critical review, please consider the above points, and treat your early results with the skepticism they warrant.

Personally, I'm curious to see if this "Letter" winds up being "published" anyway...

 

[AZCat]

Another very good point. Basically the only way to accomplish this would be to strip the walls and replace them with some sort of "explosive" drywall. And then there is the issue of making it happen sequentially. Oh, and making sure the "explosive drywall" was installed only on the floors below the impact point. I'm not trying to be a donkey about this either, i'm just trying to apply some logic .

You could coat 4" rebar with C4...

A couple of years back I calculated the amount of explosives needed using Hoffman's energy calculations for the pulverization of the concrete. His "net energy deficiency" was 9,741,600 MJ, which is equivalent to approximately 2,300 tons of TNT (2,100,000 kg). I had difficulty finding an equivalent for plastic explosive, but based on some sketchy numbers figured between 1,300 and 1,700 tons of RDX (1,200,000 to 1,500,000 kg).

2,300 tons TNT is a cube measuring approximately 35 feet (11 meters) on each side.
1,,300 to 1,700 tons RDX is a cube measuring approximately 28-31 feet (8-1/2 to 9-1/2 meters) on each side.

As a comparison, I pointed out that the Oklahoma City bombing in 1995 used 2-1/2 tons of AFNO (2,300 kg), which is slightly less powerful than TNT.

As someone upthread pointed out, this is based on a 100% energy transfer from explosion to pulverization. I have no idea what the real rate would be, but I'd be willing to bet it is considerably less than 100%.

 

[jaydeehess]

Another very good point. Basically the only way to accomplish this would be to strip the walls and replace them with some sort of "explosive" drywall. And then there is the issue of making it happen sequentially. Oh, and making sure the "explosive drywall" was installed only on the floors below the impact point. I'm not trying to be a donkey about this either, i'm just trying to apply some logic .

Actually I was thinking that it would require that trenchs be dug in the concrete flooring, explosives set in the trench, detonators installed and then the trench refilled with new concrete. For the best use of the energy of these explosives in pulverising the concrete one would want to time the trenchs to detonate starting with those closest to the core and then inward ending with the trenchs closest to the core, and of course you need each floor to be timed to match the collapse itself.

The falling debris will take care of the drywall.