new compilation - video of tower collapses - How Strong is the Evidence?

[Viva_La_Revolution]

http://www.plaguepuppy.net/public_html/collapse%20update/#stills

How Strong Is The Evidence For A Controlled Demolition?

There are quite a few still pictures showing what can only be described as explosive ejections of material from the towers, pulverized concrete and shattered pieces of the steel perimeter columns thrown out even in the early stages of the collapses. Some of these, for example the south tower pictures below, show clear rings of explosions running completely around the building just below the point of collapse. In other pictures we see extremely energetic ejection of debris that simply cannot be accounted for by gravitational forces. The immense volume of pulverized material generated early in the collapse gives rise to a phenomenon usually seen only in volcanoes, a pyroclastic flow that can be seen in some of the videos racing down the surrounding streets.

Gallery of Explosion Pictures

One of the best sources for still photos of the collapses and their aftermath is Here Is New York,
http://hereisnewyork.org/
the source of several of the pictures on this page. This collection of pictures can be searched by topic, with a very large number of actual collapse pictures. Many of these images show the explosive nature of the collapses, the violent ejection of large amounts of powdered concrete and shattered steel and the huge pyroclastic clouds formed.

[ROH]

1. Thanks for the link to the pictures at...

"Here is New York", including some very useful images.


You wrote: "How Strong Is The Evidence For A Controlled Demolition?"

Check out these links:
http://www.911research.com/wtc/analysis/towers.html
http://www.911research.com/wtc/analysis/proofs/speed.html
http://www.911research.com/wtc/analysis/proofs/volume.html
http://www.911research.com/papers/dustvolume/volumev3.html
http://www.911research.com/wtc/analysis/fires/index.html

[LARED]

3. Not very strong in this "analysis"

From http://www.911research.com/wtc/analysis/proofs/speed.html

Air resistance alone could account for the slowing of the falls to the point where each tower took about 15 seconds to completely come down.

Is really not possible. It takes over 50 percent of the potential energy available to slow the free fall to 15 seconds by air resistance alone. Or another way to state this is that the energy utilized via air resistance to slow the fall is over 50% of the energy available in a tower. The amount of air mass required to utilize this energy is not available.

The potential energy of the towers is mass * gravity * height


All of that potential energy is converted into kinetic energy or 0.5 * mass * velocity^2. If air resistance is enough to slow the fall from 9.2 seconds to 15 seconds it is easy to find the percentage of energy needed by the air to accomplish this. The difference between the two is the so called air resistance. Take this and divide it by the total energy and it is a very large percentage.

[ROH]

4. I'm not sure you have really understood this yet, have you?

You have already written about this general subject in another thread, including several self-contradictory comments, and a self-deleted message:
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=125&topic_id=40404&mesg_id=40404


Now you write:
-------------------------------
If air resistance is enough to slow the fall from 9.2 seconds to 15 seconds it is easy to find the percentage of energy needed by the air to accomplish this.
-------------------------------

For clarification please mention the percentage figure you have calculated, and how you have derived this percentage.


You also write:
-------------------------------
It takes over 50 percent of the potential energy available to slow the free fall to 15 seconds by air resistance alone. Or another way to state this is that the energy utilized via air resistance to slow the fall is over 50% of the energy available in a tower.
-------------------------------

No, aren't you simply confusing the relationship between two different aspects: air resistance and the tower's potential energy? The original article mentions a block of wood "ten inches on a side" falling a total distance of approximately 1,365 feet subject to air resistance from the roof of a tower (note that the WTC North Tower was 1,368 feet in height excluding the antenna, while the South Tower was 1,362 feet in height).

You brought up the subject of the element lead, so I asked you to also picture a lead block of the same dimensions as that block of wood. Both of these blocks (one wood, one lead) are dropped at the same time from 1,365 feet in the air from the roof of the tower. Remembering that this is not an experiment in a vacuum, which block hits the ground first? Let's call this Question 1, and hopefully you can now answer this question, please.

For Question 2, instead of the two blocks being dropped from the roof of a tower, the two blocks (one wood, one lead) are dropped at the same time out of an airplane's cargo bay at a height of 1,365 feet above the ground. In these circumstances which block would hit the ground first?

So please give your answers to these questions, and then explain the relevance of the potential energy of a tower for your answers to both questions, particularly the second question?

[LARED]

5. But, have you???

I took a different approach to the problem because after your comments it was clear I needed to explain stuff in better detail. Principles I took for granted that everyone would understand was not going to be a realistic approach so I’ve spelled it out in detail.

The author indicates that

Air resistance alone could account for the slowing of the falls to the point where each tower took about 15 seconds to completely come down.

Creating a simplified model of energy conservation one can get a perspective on the amount of energy required to slow the tower collapse from 9.2 to 15 sec.

Let me explain. The total available energy of a tower can be expressed as potential energy.

PE = mgh m= mass, g =gravity 32.2 ft/sec^2 h= height = 1350.

To find the free fall speed with no air resistance, one uses to the conservation of energy principle. The potential energy of a tower is converted to kinetic energy during its collapse conserving mass and energy.

KE = ½mv^2 (m =mass, v = velocity)

So because PE is equal to KE then => mgh= 0.5mv^2

Since v =at, a= acceleration or g in this case, and t= time. mgh = 0.5m(at)^2

t = (2h/a)^.5 or 9.17 sec.

So far we have figured out free fall time by using the conservation of energy principle. (very basic stuff and relevant)

So we can extend this concept a little to include the author’s conclusion that air resistance alone can account for a fall time of 15 seconds.

Assuming this, one can state that the total energy expended in the collapse scenario where it takes 15 seconds is the sum of the free fall energy plus the air resistance energy. (This of course neglects the energy utilized in the destruction of the building)

Lets describe it as;

KE(fall in 15 sec) = KE(freefall) + energy of the air drag. Lets call that (Eair)

So substituting PE for KE(freefall) to simplify

1/2mv^2 = mgh + Eair

Or

Eair= 1/2mv^2 - mgh

Since we don’t know the final velocity for the 15 second collapse and v = 2h/t, we will substitute for v.

Eair = 1/2m(2h/t)^2 - mgh

Mass of a tower is approx 500,000 tons

Eair = m(0.5(2h/t)^2- gh)

Eair= -2.73 e13 (the neg means it is operating opposite to freefall)

Looking back at the total available energy in absolute terms.

PE = mgh = 4.34 e13

The ratio is 2.73 / 4.34 = 0.63 or 63 percent

So, providing enough energy to slow down a tower’s descent from 9.17 sec to 15 sec, requires approx 63 percent of the total energy available in the towers. This energy is manifested as air drag.

Considering this 63 percent energy number requires a mass of air to resist the fall it might be instructive to look at how much air mass was available. At 1350 feet tall and 200 by 200 feet square there is approx 54 million cubic feet in a tower. The mass of air inside is just over 2,000 tons using standard air density. I’ll double it to consider outside air.

The ratio of the mass of air and the mass of the tower is then 4,000/500,000 or 0.008. So for every pound of air resisting freefall there is 125 pounds of tower to resist. Where does the pound of air mass of air get the energy to slow down 125 pounds of tower? From the tower of course. As it impacts the air in freefall. How does an energy ratio of 0.63 jive with a mass ratio of 0.008. It does not. There is simply not enough air mass to counter freefall in the way the author concludes.

It is not a simple matter to determine air drag on a collapsing structure like the WTC. It might be impossible. But what my little exercise in energy conservation shows is that there no way possible there is enough air mass to impede the towers enough to slow it fall from 9.17 second to 15 seconds.

Of course if the air resistance is negligible and the real energy consumer was work in the form of the building being destroyed, hence slowing it’s descent to 15 seconds that would make sense.

I almost forgot, the lead hits first in both cases.

[ROH]

7. You are simply ignoring all the other energy sources in the WTC towers...

You write:
------------------------------
The total available energy of a tower can be expressed as potential energy.

PE = mgh m= mass, g =gravity 32.2 ft/sec^2 h= height = 1350.
------------------------------

No, that equation only gives the gravitational potential energy of a tower. You are merely considering the mass and height of the towers, and you are taking no account of the specific design considerations of the structures; remember that the WTC towers were even "over-engineered" - see: http://www.911research.com/wtc/analysis/design.html

For example, consider the steel core columns:
http://www.911research.com/wtc/arch/core.html
http://www.911research.com/wtc/analysis/collapses/steel.html
------------------------------
The primary core columns were steel box-columns measuring 36 inches by 16 inches. These columns were continuous for their entire height, going from their bedrock anchors in the sub-basement to near the towers' tops, where they transitioned to H-beams.

The only large remnants of the towers standing after the collapses were base sections of the perimeter walls extending upward several stories. Some of these sections were about 200 feet wide by 80 feet tall. Virtually all of the remaining steel was broken up into small pieces:

* There were no remnants of the core structures that rose much above the rubble piles.
* Most of the perimeter walls above the standing bases were broken up into the three-floor by three-column prefabricated sections, and many of those sections were ripped apart at the welds.
* There were no large sections of the corrugated pans underlaying the floor slabs or the trussing beneath them.
------------------------------

Do you realize the extent of the kinetic energy released when each piece of steel snaps, however that breakage was caused?

If your energy discussion is to be worthwhile, you need to look at all the sources of energy not just the gravitational potential energy.


The subject of the WTC collapses is very important, and you have already unsuccessfully attempted to claim that the original writer was wrong in particular respects. So would you please at least conclude the earlier discussions about your incorrect views before attempting to make other arguments? Please would you reply to the following questions:

Question 1: Using your own proposition for clarity...
You have two basket balls. One is filled with air and the other is filled with lead. Both are dropped from 200 feet in the air. Which one hits the ground first? You originally answered: "The lead filled one is at least 1000 times denser that the air filled one, yet both will hit the ground simultaneously because the drag of air on them is the same." Would you now give a different answer, or would you still claim that your original answer is correct?

Question 2: You wrote: "The density of the wood has nothing to do with the density of the towers and the density of either has nothing to do with fall time." Do you now appreciate that fall time through air depends upon the density of the object?

Question 3: You wrote: "The author of the article starts with the false premise that the density of the tower has some material effect on the fall time ..." Do you now consider that the author's premise is correct? If not, please explain why this seems to be a false premise to you?

[LARED]

8. Other energy sources?????

What other energy sources?

[ROH]

9. Check out:

http://www.911research.com/papers/dustvolume/volumev3.html
for energy calculations.

Would you answer the three questions I asked, please, or do you prefer not to answer for some reason?

[LARED]

11. Been checked out and was good for a laugh

Yes, I've read Hoffman's fantasy. Even he only speaks about potential energy as the source.

Regarding your questions.

Question 1: Actually I would give a different question as I screwed up what I wanted to say. I've already indicated I messed up trying to get my point across. And before you ask again the answer is incorrect. Happy?

Question 2: Again my point was the density of wood has nothing to do with the density of the towers. Apples and oranges.

Question 3: The author's premise that towers density has a material effect on the fall time is still silly. It's effect is minuscule.

Now I've answered your questions so kindly answer mine.

What other sources of energy are you talking about?

[ROH]

12. Haven't you missed the point yet again?

You wrote:
------------------------------
Even he only speaks about potential energy as the source.
------------------------------

No, he also refers to the energy released by the fires that preceded the collapses. He continues in his article by concentrating on the gravitational potential energy in his calculations as being the major universally acknowledged energy source at this time.

The main points to emphasize are that he states: "The imbalance between sources and sinks is striking, no matter the relative shares of the thermodynamic and water vaporization sinks in accounting for the expansion. ... The amount of energy required to expand the North Tower's dust cloud was many times the entire potential energy of the tower's elevated mass due to gravity. ... The official explanation that the Twin Tower collapses were gravity-driven events appears insufficient to account for the documented energy flows."

Question 1: Do you agree with this comment in the article: "However, FEMA's Building Performance Assessment Report gives an estimate: "Construction of WTC 1 resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure." That is equal to about 111,000 KWH (kilowatt hours) per tower."?



You wrote:
------------------------------
Actually I would give a different question as I screwed up what I wanted to say. I've already indicated I messed up trying to get my point across. And before you ask again the answer is incorrect.
------------------------------

Thank you for being willing to acknowledge your mistake. I appreciate that. If you had properly read the references in the first place, you would not have wasted time making false assertions that frankly indicated that you had a poor knowledge of basic physics.


You wrote:
------------------------------
Again my point was the density of wood has nothing to do with the density of the towers.
------------------------------

Now you have reverted to contradicting yourself once again. In your earlier message in reply to his comments: "The rubble from the tower probably had similar average density to our block of wood, since the floor slabs consisted of corrugated sheet metal and lightweight concrete, and the perimeter steel columns were hollow with walls only 1/4th inch thick at the towers' tops.", you wrote: "Possible ..."

Question 2: You can't have it both ways: do you think that the comparative densities are (a) possibly similar, or (b) definitely not?


You wrote:
------------------------------
The author's premise that towers density has a material effect on the fall time is still silly.
------------------------------

So let's get this straight: despite all your earlier extensive protestations to the contrary, you now accept that the author's premise has been correct all along, but it just seems "silly" to you. Thank you for acknowledging another error on your part.


You wrote:
------------------------------
What other sources of energy are you talking about?
------------------------------

The article states that "the amount of energy required to expand the North Tower's dust cloud was many times the entire potential energy of the tower's elevated mass due to gravity." Therefore, following the conclusion of the article, this would mean that there are other energy sources which you have not allowed for, and those are the energy sources that I am referring to. Some commentators have speculated that these other energy sources were explosives, but whatever the actual nature of these sources, the article concludes that there is a major discrepancy between the gravitational potential energy source and the total of the energy sinks. Will you allow for this discrepancy (i.e. other sources of energy) in your calculations?

[LARED]

13. Now you're avoiding my question

You stated

No, that equation only gives the gravitational potential energy of a tower. You are merely considering the mass and height of the towers, and you are taking no account of the specific design considerations of the structures; remember that the WTC towers were even "over-engineered"

What over-engineering added energy to the collapse?

You then add

Do you realize the extent of the kinetic energy released when each piece of steel snaps, however that breakage was caused?

If your energy discussion is to be worthwhile, you need to look at all the sources of energy not just the gravitational potential

You seem to indicate the kinetic energy is a source. Are you stating by that statement?

On to your last comments

No, he (Hoffman) also refers to the energy released by the fires that preceded the collapses. He continues in his article by concentrating on the gravitational potential energy in his calculations as being the major universally acknowledged energy source at this time.

Please explain to this poor engineer how those fires added energy to the collapse.

Your response to my question is to quote Hoffman’s work of imagination

The article states that "the amount of energy required to expand the North Tower's dust cloud was many times the entire potential energy of the tower's elevated mass due to gravity." Therefore, following the conclusion of the article, this would mean that there are other energy sources which you have not allowed for, and those are the energy sources that I am referring to.

I am not interested in what Hoffman “thinks,” I have made it clear I consider his work to be pure sophistry. Where do you think the other energy sources came from that slowed to towers descent to 15 sec?

Some commentators have speculated that these other energy sources were explosives, but whatever the actual nature of these sources, the article concludes that there is a major discrepancy between the gravitational potential energy source and the total of the energy sinks.

Remember that the energy sources you seek must act to slow the fall? What outside energy sources would do that? Also if you look at my equation the air drag is considered an energy source, not a sink, to account for the additional energy required to slow the fall. Why not just admit you are clueless as to the implications of my little energy balance?

Will you allow for this discrepancy (i.e. other sources of energy) in your calculations?

Sure, right after you tell me what they are?

[ROH]

14. No. Do you ever realize the extent of the hypocrisy of your comments?

I asked you the following two questions:

Question 1: Do you agree with this comment in the article: "However, FEMA's Building Performance Assessment Report gives an estimate: "Construction of WTC 1 resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure." That is equal to about 111,000 KWH (kilowatt hours) per tower."?

Question 2: You can't have it both ways: do you think that the comparative densities are (a) possibly similar, or (b) definitely not?

For some reason you chose not to answer either question. In fact you have already clearly ignored the second question in an earlier thread. So can you answer these questions?


You wrote:
------------------------------
What over-engineering added energy to the collapse?

You then add

Do you realize the extent of the kinetic energy released when each piece of steel snaps, however that breakage was caused?

If your energy discussion is to be worthwhile, you need to look at all the sources of energy not just the gravitational potential

You seem to indicate the kinetic energy is a source. Are you stating by that statement? (sic.)
------------------------------

If you actually read the comments, you would see that I wrote that kinetic energy was released. I did not state that kinetic energy was the source; if you can answer and comprehend the basis of Question 1 above, you may be able to appreciate FEMA's remark that construction of WTC 1 "resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure".


You wrote:
------------------------------
Please explain to this poor engineer how those fires added energy to the collapse.
------------------------------

In fact the author stated: "The accepted source of this energy was the gravitational potential energy of the towers, which was far greater than the energy released by the fires that preceded the collapses."


You wrote:
------------------------------
I have made it clear I consider his work to be pure sophistry.
------------------------------

Question 3: Which one of his figures do you disagree with, and why do you disagree with that figure?


You wrote:
------------------------------
What outside energy sources would do that?
------------------------------

Considering the proposition of an explosive, wouldn't an explosion occurring below a falling object exert an upward force on that object. If you think it would not, please explain your reasoning.


You wrote:
------------------------------
Where do you think the other energy sources came from that slowed to towers descent to 15 sec?
------------------------------

The author's postulation is air resistance, and in fact you have already stated yourself (with the regard to the distance under discussion) that you think it is possible that in the air a block of wood, ten inches on a side, might take 50 percent longer to fall than it would in a vacuum.

The author writes: "Air resistance alone could account for the slowing of the falls to the point where each tower took about 15 seconds to completely come down."

Some simulations to illustrate air resistance: http://www.interactivephysics.com/simulationlibrary/airresistance.html


You wrote:
------------------------------
Sure, right after someone you tell me what they are? (sic.)
------------------------------

Again if you can answer Question 1 you may understand the relevance of FEMA's remark that construction of WTC 1 "resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure".

Putting that information into your calculations might be a worthwhile step for you.

[LARED]

15. You like to ask a lot of questions

But do not seem to have the capacity to answer any.

I'll try one more time.

What other energy sources

You need need to answer this question honestly to show me you're capable of dicussing this.

After that I'll anwser anything you like.

Putting that information into your calculations could be a worthwhile starting point for you.

That's already in my calculation -> PE

From Hoffman's fantasy piece.

However, FEMA's Building Performance Assessment Report gives an estimate: "Construction of WTC 1 resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure." That is equal to about 111,000 KWH (kilowatt hours) per tower.

[ROH]

16. So you are still choosing to avoid answering the questions!

You write:
------------------------------
What other energy sources
------------------------------

I have already answered you, but you seem unable to comprehend.

So let's take the discussion slowly in simple a/b/c terms:

(a) You have only discussed basic gravitational potential energy of an object in terms of mass x gravity x height.

(b) What about the storage of potential energy that results from the construction of a complex building structure. FEMA's Building Performance Assessment Report provides us with an estimate: "Construction of WTC 1 resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure."

(c) Air resistance is distinct to the potential energy of a tower; consider an object falling in air nowhere near to a tower. Surely you can appreciate that!


You write:
------------------------------
That's already in my calculation -> PE
------------------------------

Calculate the resulting number of joules of energy for yourself derived from mass x gravity x height. Then look again at FEMA's comments: "Construction of WTC 1 resulted in the storage of more than 4 x 10^11 joules of potential energy over the 1,368-foot height of the structure." I take it that you are satisfied with FEMA's comments, since you have mentioned their report yourself in other threads? I can't be sure whether you accept this figure or not, because, for reasons best know to yourself, you have simply declined to answer the question so far.


Now, would you please at least attempt to answer the questions I have put to you.

[LARED]

19. Yes, simple seems to be the operative idea

In my energy system the potential energy I used is defined as mgh because I am making a comparison between the height and mass of the building and how that mass gets turned into kinetic energy. FEMA's estimate of stored potential energy is not material to my system. I don't know how they arrived at it, as they do not say. Again it does not matter in my system.

My simple model uses the same method one uses to find the free-fall time or velocity of an object dropped from a height. A very basic energy balancing method found in any high school physics book. Absent of air resistance all the potential energy gets converted to kinetic energy. Knowing that KE = 1/2MV^2 one can find velocity based on time and height. Of course you understand this.

If you assume the free-fall energy was countered by air resistance and you know the actual fall time and distance, you can relate the amount of potential energy converted into work countering air resistance.

It's not sophisticated, It's not supposed to be. I only used it to make a comparison between the available gravitational PE and how much of it gets used countering air resistance if one uses 15 seconds a the fall time. The number is a very high percentage

The air resistance requires air mass to counter the mass of the tower collapsing. The mass ratio of the tower to air is at least 250 to 1. Meaning there is a huge requirement for air mass to counter the towers fall at the percentage of energy required. There is no way there is enough air alone to counter the fall creating a time of 15 seconds.

If you have a comment that is constructive please post it.

[ROH]

21. Thank you for giving more information about your line of reasoning...

You write:
------------------------------
The air resistance requires air mass to counter the mass of the tower collapsing. The mass ratio of the tower to air is at least 250 to 1.
------------------------------

It's interesting to note that the original writer's suggestion of a wood block gives an approximate density ratio in air of 461.5 to 1:
* the density of wood is approximately 0.6 gm/cm^3 (wood densities obviously vary to some extent: http://www.mcelwee.net/html/densities_of_various_materials.html ), and
* the density of air at STP is 0.0013 gm/cm^3.

STP could be an important factor to consider: in the supposed pancaking collapse theory how much compression of air would occur as one floor collapsed swiftly (less than 1/6th of a second on average per floor) onto the floor below?


Anyway please correct your earlier calculations, tidy your presentation (e.g. show specific units such as joules or KWH), reconsider FEMA's official figures, and we can then take the whole discussion further if you wish.

[ROH]

22. I am interested in your energy ideas if useful additional information...

can be gleaned from them.

I think you probably misunderstood when I mentioned that your equation of a tower's gravitational PE is wrong. The most important point is that you are calculating a WTC tower's gravitational PE using the equation mgh with m = the mass of the tower, g = the acceleration due to gravity, and h = 1350 feet (i.e. the approximate height of a WTC tower). This is wrong unless you are assuming that the center of mass of the tower is at the top of the tower. Working on the basis of a uniform linear mass density, integrate the potential energy formula over the height of the tower:
the center of mass of the tower is at its geometric center, halfway up.

So, working on the basis of your other figures, the calculation of a WTC tower's gravitational PE should be approximately 500000 x 2000 x 32.2 x 1350 / 2 = 2.17 e13 (half your original answer of 4.34 e13).

Your Eair value involves the result of your tower's gravitational PE equation, so your Eair calculation also needs to be corrected.

[ROH]

17. You know that your equation of a tower's gravitational PE is wrong anyway?

You wrote:
------------------------------
The total available energy of a tower can be expressed as potential energy.

PE = mgh m= mass (500,000 tons), g =gravity 32.2 ft/sec^2, h= height = 1350.
------------------------------

Check basic physics information and you will see that your equation for the gravitational PE of a tower is incorrect. So please correct this howler first if you still want to continue to pursue your line of reasoning.

[LARED]

18. Well, good observation (pointing out you did not read the whole piece)

I wonder if you also made the observation that I used pounds (500,000 tons * 2000 pounds/ton) when I added it altogether at the end. Of course not. You're not interesting in a discussion.

This indicates to me you are more interested in obfuscating my point regarding air resistance not being capable of slowing the towers fall to 15 sec, than you are in discussing the energy balance I devised. Try actually attempting to grasp the basic energy transfer principles and you might actually figure it out. I'm not trying to devise a rigorous description of the collapse, I'm merely pointing out that there is not anything close to enough air mass acting alone to slow the fall to 15 seconds.

I'm beginning to believe the "H" in ROH stand for Hoffman. You certainly have his flair for sophistry.

[ROH]

20. I read the whole piece when it first appeared, but why do you possibly...

expect me (or anyone else) to point out all of your multifarious errors to you? How many mistakes have you made in total now, accepted even by your own admission? I'm not your supervisor or manager after all.

Anyway I thank you again for now acknowledging more errors in your comments. Your willingness (at least when you are pressed) to recognize your various discrepancies is appreciated.


You write:
------------------------------
I wonder if you also made the observation that I used pounds (500,000 tons * 2000 pounds/ton) when I added it altogether at the end.
------------------------------

In fact you didn't state any energy units at all for the PE figure you calculated (i.e. 4.34 e13), so that is one reason I suggested that you formulate your calculation into joules for comparison with FEMA's own figures.


You write:
------------------------------
This indicates to me you are more interested in obfuscating my point regarding air resistance not being capable of slowing the towers fall to 15 sec, than you are in discussing the energy balance I devised.
------------------------------

Your indications are wrong. If you correct all the errors in your calculations, take into account FEMA's quote about the potential energy, and show appropriate units (e.g. joules or KWH, etc.) for clarity we can certainly discuss any relevance it may have with respect to air resistance and to the analysis of: http://www.911research.com/papers/dustvolume/volumev3.html


You write:
------------------------------
I'm not trying to devise a rigorous description of the collapse, I'm merely pointing out that there is not anything close to enough air mass acting alone to slow the fall to 15 seconds.
------------------------------

In that case:

1. Why did you state (with the regard to the distance under discussion) that you think it is possible that in the air a block of wood, ten inches on a side, might take 50 percent longer to fall than it would in a vacuum?

2. Why do you bring a tower's potential energy into an air resistance discussion, when air resistance is distinct to the potential energy of a tower; again consider an object falling in air nowhere near to a tower? Do you find any difficulty in appreciating the distinction between them?

Will you answer any of the outstanding questions? On the basis of your previous responses, it is more likely that you will shy away from the questions.

You have so far, after several abortive attempts, offered no serious rebuttal to any of the comments in the articles originally referenced (in the earlier thread) by "spooked911". Thank you for making some attempts anyway.

[philb]

2. I've looked at the pictures and read the studies and think case is strong

that the towers werent' brought down by fire. It took a lot of energy to blast apart those steel beams and throw them outward, and to pulverize all of that concrete. Gravity would not do it; and the studies I've seen support that conclusion.

[ROH]

6. Link:

http://www.911research.com/wtc/analysis/collapses/steel.html

[Christophera]

10. Evidence Shows A Building Built For Demolition

Ther required quantities of explosives could not have been placed optimally nor distributed optimally, both absolutely needed to effect what was seen.

There were no free escaping gas jets. All the explosion was moving heavy mass with an effciency never seen. The pulverized result proves this. The free fall proves this.

Here is the only explanation that uses all of the information consistent with itself.

http://algoxy.com/psych/9-11scenario.html