9-11 Presentation at NMSR, May 19 2010

[triforcharity]

pssssst............your talking to yourself. out of your ass.

ftfy. :d

 

[Slartibartfast]

And with that, I bow out. If we can't agree on this, there's nothing more to discuss.

Mackey was right, you can't fix stupid.

Almond,

I've watched your impressive (if ultimately futile) effort here, and thought that I would give it a try (I might be a noob, but I've got a little game... )

Originally Posted by ergo
OMFG. The bowling ball does not have the same kinetic energy or momentum if it is pieces of bowling ball. What part of this don't you understand? When it falls to the floor (which was not the analogy I used) both the ball and the floor must absorb the impact. Got it?

Ergo,

Would you agree that a 5 kilo bowling ball moving at, say 100 m/s has the same kinetic energy as 5 kilos of bowling ball bits moving at 100 m/s? (Namely they both have 50 kiloJoules of kinetic energy.) The same is true of the upper block, whether it is intact or in bits, right? Now there is some energy loss due to energy to eject materials and loss of mass, but let's set that aside for now.

Here is what I believe happened upon impact with the ground (this is simpler than the impact of the upper block with the lower block, so it's a good place to start - please let me know what you don't agree with or what I'm not considering that you were trying to imply with your bowling ball impact example. (The exact numbers I'm using are not important, but I like to get a ballpark feel for the quantities involved). Assume that WTC1 had 400 gigaJoules of gravitational potential energy on the morning of 9/11 and that it collapsed in 12.59s resulting in a seismic event measuring 2.3 on the Richter scale. At the moment before the crash reached ground level there was a mass of debris traveling down at about 66 m/s which translates to about 215 GJ of kinetic energy (the rest already having been dissipated in destroying the structure of the building, pulverizing concrete, ejecting the dust cloud and debris, etc. After impact there was a stationary pile of debris, so we will treat the impact as if it were a single inelastic collision. Since there is no motion after the impact, 215 GJ of kinetic energy was dissipated. Where did that energy go? Well, a negligible amount went into vibrations in the air (sonic energy), roughly 12 GJ went into vibrations in the Earth (seismic energy) and the rest was converted into thermal energy in the rubble and the ground via internal friction due to the deformation of materials. Do you agree with this analysis?

 

[Sam.I.Am]

Welcome Slartibartfast. You can't argue with someone who doesn't listen even after numerous people have shown in many different ways that he's wrong, but good luck trying. Try not to get too many splinters in your forehead while slamming your head on the desk. The chicks don't dig that look.

 

[Slartibartfast]

Welcome Slartibartfast. You can't argue with someone who doesn't listen even after numerous people have shown in many different ways that he's wrong, but good luck trying. Try not to get too many splinters in your forehead while slamming your head on the desk. The chicks don't dig that look.

Don't worry about me, I've got a hard head and some irrepressible optimism that needs curing...

 

[ergo]

Almond,

Here is what I believe happened upon impact with the ground

The impact of what with the ground? Thank you.

Assume that WTC1 had 400 gigaJoules of gravitational potential energy on the morning of 9/11 and that it collapsed in 12.59s resulting in a seismic event measuring 2.3 on the Richter scale. At the moment before the crash...

The "crash" of what, again? Thank you.

... reached ground level there was a mass of debris traveling down at about 66 m/s...

How does debris travel down at 66m/s through 80 and 90 intact floors of structural steel and concrete? Thank you.

...which translates to about 215 GJ of kinetic energy (the rest already having been dissipated in destroying the structure of the building, pulverizing concrete, ejecting the dust cloud and debris, etc.

Again, you can't have that kind of velocity accompanying crushing and pulverizing.

After impact,

Of what against what? Thank you.

there was a stationary pile of debris, so we will treat the impact

of what?

as if it were a single inelastic collision. Since there is no motion after the impact,

The impact of what against what?

215 GJ of kinetic energy was dissipated.

Not sure how it matters, but are you picking this value out of your ass? You don't show how you arrive at it.

Where did that energy go?

Who cares?

Well, a negligible amount went into vibrations in the air (sonic energy), roughly 12 GJ went into vibrations in the Earth (seismic energy) and the rest was converted into thermal energy in the rubble and the ground via internal friction due to the deformation of materials.

Again, how do you arrive at your number, and what is the relevance of this to anything we've been discussing? Thank you.

Do you agree with this analysis?

I can hopefully answer that when you explain what it is you're analyzing and why it matters to prove or disprove crush-down, crush-up in the WTC.

 

[Sam.I.Am]

This is the level of discussion that you can expect here from someone like ergo. Nitpicking the obvious and irrelevant so that they can think that they make points while handwaving away that which is actually relevant.

Watch out for the splinters...

 

[ergo]

A lot of "debunkers" seem to specialize in vague and imprecise language and dodging plainly spoken, direct questions.

I can only assume it's to mask that

1) they don't really have a clue what they pretend to have a clue about, or
2) they have a clue but know that what they are arguing is indefensible so they mumble vaguenesses, clichés and platitudes, use bizarre, broken logic, and/or hurl insults and accusations in the hopes that you will be too distracted to see the gaping holes.

 

[Slartibartfast]

Ergo,

I am just trying to establish the basic physics of the situation and determine where you disagree with what Almond was saying (you may assume that I agree with Almond). I don't think that a productive debate can occur without agreeing on the ground rules (in this case, the physics involved).

The impact of what with the ground? Thank you.

The impact of the falling debris with the ground.

The "crash" of what, again? Thank you.

'Crash' again referring to the impact of the debris with the ground.

How does debris travel down at 66m/s through 80 and 90 intact floors of structural steel and concrete?

66m/s is the speed that an object that traveled from the top of the WTC to the ground in 12.59s at constant acceleration would be going when it hit the ground. Consider it a rough estimate of the average speed of debris upon hitting the ground (Again, the exact value of the numbers are not important - I just find it intuitively helpful. Also, you can't do calculations of without numbers... ) Since the collapse did travel down through 90 or so intact floors in the space of roughly 13s, we know that the collapse front was moving at something like that speed when it impacted ground level. I'm assuming nothing about HOW the debris traveled through all those floors, just that they did travel through all of those floors.

Again, you can't have that kind of velocity accompanying crushing and pulverizing.

Why not? The velocity had to be something like that given the time of collapse - this is not meant to be anything more than a very rough estimate (I'm interested in the concepts of energy and momentum as these are what you seem to disagree about, not the exact values of these quantities for the collapse). I can make a case for where all of the gravitational potential energy went in the collapse, but I don't think that it is germane here.

Of what against what?

The falling debris impacting the ground.

Not sure how it matters, but are you picking this value [the kinetic energy of the debris before impact] out of your ass? You don't show how you arrive at it.

I don't think it matters to this conversation, but I got the number by assuming that the ratio of the value in question to the total GPE was equal to the ratio of the squares of the velocity calculated above and the free-fall impact velocity.

Who cares? [what happened to the energy]

Since energy is always conserved, it is a useful quantity in analyzing events like this (plus your disagreement with Almond involved energy).

Again, how do you arrive at your number [~12 GJ of seismic energy], and what is the relevance of this to anything we've been discussing?

A seismic event which registers 2.3 on the Richter scale (like the collapse of WTC1) dissipates about 12 GJ of energy. In order to resolve the disagreement over the kinetic energy of the bowling ball/bowling ball pieces we need to consider kinetic energy and what happens to it.

I can hopefully answer that when you explain what it is you're analyzing and why it matters to prove or disprove crush-down, crush-up in the WTC.

I'm trying to establish the basics of conservation of energy in order to provide a basis for discussing a crush-down/crush-up collapse. No reasoned debate is possible if the two sides disagree about the physical principles involved.

 

[Slartibartfast]

A lot of "debunkers" seem to specialize in vague and imprecise language and dodging plainly spoken, direct questions.

I can only assume it's to mask that

1) they don't really have a clue what they pretend to have a clue about, or
2) they have a clue but know that what they are arguing is indefensible so they mumble vaguenesses, clichés and platitudes, use bizarre, broken logic, and/or hurl insults and accusations in the hopes that you will be too distracted to see the gaping holes.

I'll do my best to answer any questions you ask - I am attempting to establish a consensus on the physics involved in this discussion which I believe is essential to any sort of reasonable debate. As far as what I do (or don't) have a clue about, I am a mathematical biologist (I have a PhD in math from Duke) who specializes in cell cycle modeling and I have a solid understanding of Newtonian physics from several years as a physics major as an undergrad. I'm not an expert in this, but as I said in my first post, I do have some knowledge in this area.

I believe that what I'm arguing is correct and will defend it to the best of my ability, so if you think I'm being vague, I'll gladly explain my arguments better, I'll try to keep the clichés and platitudes to a minimum, keep my logic as clean as possible (as a mathematician I have pretty strong feelings about logic and the idea of 'proof'), and I'll let you focus your attention where you will. As you might have noted from my earlier response, any numbers that I use come from somewhere and I'm always willing to clarify what calculations or sources I used to arrive at any of them.

 

[ergo]

The impact of the falling debris with the ground.

The debris did not impact the ground until the last lower floor, supposedly, was crushed through. That supposed crushing through produced debris which would already be in contact with the ground. So technically, there was no "impact" of debris with the ground. It would be debris with debris. Nor was it "falling". It was supposedly crushing through. This is not just semantics. This is getting the "debunkers" to explain their argument using the terms that were introduced and that exist as the official collapse theory.

66m/s is the speed that an object that traveled from the top of the WTC to the ground in 12.59s at constant acceleration would be going when it hit the ground. Consider it a rough estimate of the average speed of debris upon hitting the ground ... Since the collapse did travel down through 90 or so intact floors in the space of roughly 13s, we know that the collapse front was moving at something like that speed when it impacted ground level. I'm assuming nothing about HOW the debris traveled through all those floors, just that they did travel through all of those floors.

Obviously I don't agree with this model of the collapse.

Why not? The velocity had to be something like that given the time of collapse -

I agree that the collapse front, for lack of a better term, descended at that speed. I do not agree that debris moved through a third of a kilometre high of building at that speed.

Since energy is always conserved, it is a useful quantity in analyzing events like this

Still waiting to find out what you're analyzing.

A seismic event which registers 2.3 on the Richter scale (like the collapse of WTC1) dissipates about 12 GJ of energy. In order to resolve the disagreement over the kinetic energy of the bowling ball/bowling ball pieces we need to consider kinetic energy and what happens to it.

Okay.

I'm trying to establish the basics of conservation of energy in order to provide a basis for discussing a crush-down/crush-up collapse. No reasoned debate is possible if the two sides disagree about the physical principles involved.

I'm not sure in what ways you think you have established the "basics", and it sure wasn't a convincing start, but I'll suspend my disbelief for now. Why are you using conservation of energy which is applicable only to isolated systems?

 

[ergo]

I believe that what I'm arguing is correct and will defend it to the best of my ability, so if you think I'm being vague, I'll gladly explain my arguments better, I'll try to keep the clichés and platitudes to a minimum, keep my logic as clean as possible (as a mathematician I have pretty strong feelings about logic and the idea of 'proof'), and I'll let you focus your attention where you will. As you might have noted from my earlier response, any numbers that I use come from somewhere and I'm always willing to clarify what calculations or sources I used to arrive at any of them.

Great.

 

[Slartibartfast]

The debris did not impact the ground until the last lower floor, supposedly, was crushed through. That supposed crushing through produced debris which would already be in contact with the ground. So technically, there was no "impact" of debris with the ground. It would be debris with debris. Nor was it "falling". It was supposedly crushing through. This is not just semantics. This is getting the "debunkers" to explain their argument using the terms that were introduced and that exist as the official collapse theory.

Each piece of debris was torn loose from the structure of the building and ended its 'career', so to speak, in an inelastic collision with the ground (or the rubble pile). As the purpose of this example is just an attempt to get us both on the same page as far as the physics are concerned, I don't think this point is important to clear up right now (although if you would like to elaborate on what the distinction you're trying to make here is, that's fine by me).

Obviously I don't agree with this model of the collapse.

That's a given - as I said, I'm just trying to lay out a scenario in which we can come to a consensus about the physics right now. One question from earlier that you did not answer: do you agree that two objects or groups of objects with the same mass traveling at the same speed have the same kinetic energy?

I agree that the collapse front, for lack of a better term, descended at that speed. I do not agree that debris moved through a third of a kilometre high of building at that speed.

That was just an estimate of the speed of the debris immediately before impact - at that point the speed of the mass of debris and the speed of the collapse front would be roughly equivalent regardless of whether or not they attained that speed with or without help (i.e. explosives).

Still waiting to find out what you're analyzing.

Until we reach some kind of consensus regarding the physics of energy and momentum, we wont be 'talking the same language' so to speak. (Also, as someone trained in mathematics I have a compulsion to make sure that everyone is using the same definitions. )

I'm not sure in what ways you think you have established the "basics", and it sure wasn't a convincing start, but I'll suspend my disbelief for now. Why are you using conservation of energy which is applicable only to isolated systems?

This comment illustrates exactly why I'm doing this - energy is conserved universally. While the total energy of a system is only conserved if the system is isolated, every instance of work conserves energy while converting it from one form to another or transferring it from one place to another. Unfortunately, I can't give you a link to support this until I've made a few more posts... (any basic physics text or Wikipedia would work, however - pun intended )

 

[dafydd]

Each piece of debris was torn loose from the structure of the building and ended its 'career', so to speak, in an inelastic collision with the ground (or the rubble pile). As the purpose of this example is just an attempt to get us both on the same page as far as the physics are concerned, I don't think this point is important to clear up right now (although if you would like to elaborate on what the distinction you're trying to make here is, that's fine by me).




That's a given - as I said, I'm just trying to lay out a scenario in which we can come to a consensus about the physics right now. One question from earlier that you did not answer: do you agree that two objects or groups of objects with the same mass traveling at the same speed have the same kinetic energy?




That was just an estimate of the speed of the debris immediately before impact - at that point the speed of the mass of debris and the speed of the collapse front would be roughly equivalent regardless of whether or not they attained that speed with or without help (i.e. explosives).




Until we reach some kind of consensus regarding the physics of energy and momentum, we wont be 'talking the same language' so to speak. (Also, as someone trained in mathematics I have a compulsion to make sure that everyone is using the same definitions. )



This comment illustrates exactly why I'm doing this - energy is conserved universally. While the total energy of a system is only conserved if the system is isolated, every instance of work conserves energy while converting it from one form to another or transferring it from one place to another. Unfortunately, I can't give you a link to support this until I've made a few more posts... (any basic physics text or Wikipedia would work, however - pun intended )

The inverted commas around career were not needed,the word was used in the right context.Things career along,not careen,as they do in the States.Careen means to drag a ship onto dry land and scrape the barnacles and seaweed off the bottom.Sorry for the diversion,back on topic.

 

[Slartibartfast]

The inverted commas around career were not needed,the word was used in the right context.Things career along,not careen,as they do in the States.Careen means to drag a ship onto dry land and scrape the barnacles and seaweed off the bottom.Sorry for the diversion,back on topic.

Noted.

 

[TruthersLie]

The inverted commas around career were not needed,the word was used in the right context.Things career along,not careen,as they do in the States.Careen means to drag a ship onto dry land and scrape the barnacles and seaweed off the bottom.Sorry for the diversion,back on topic.

Just like a Brit to abuse the english language so. As I tell all of my brit friends, I need a british to english dictionary because they have made such a ham of it.


career is what you do for a living over a long period of time.

A buoy is pronounced booo eeeee, not BOY

You don't need to add a U to every O in words... hence it is honor, color.

And lastly, your interesting use of pants, panties, jumpers, trainers and the vulgar FANNY.

Tsk tsk tsk.

 

[bill smith]

Just like a Brit to abuse the english language so. As I tell all of my brit friends, I need a british to english dictionary because they have made such a ham of it.


career is what you do for a living over a long period of time.

A buoy is pronounced booo eeeee, not BOY

You don't need to add a U to every O in words... hence it is honor, color.

And lastly, your interesting use of pants, panties, jumpers, trainers and the vulgar FANNY.

Tsk tsk tsk.

I always see American as a kind of English shorthand. Often convenient but seldom satisfactory. That's why they say that England and America are two countries seperated by a common language I suppose.

 

[DGM]

The debris did not impact the ground until the last lower floor, supposedly, was crushed through. That supposed crushing through produced debris which would already be in contact with the ground. So technically, there was no "impact" of debris with the ground. It would be debris with debris. Nor was it "falling". It was supposedly crushing through. This is not just semantics. This is getting the "debunkers" to explain their argument using the terms that were introduced and that exist as the official collapse theory.

You really shouldn't use the term "technically".

"Technically" every piece of rubble was impacting the ground from the very beginning of the collapse. Just like rain falling on the roof of a building is in fact "impacting" the ground. It's doing this through the structure of the building. I won't even start with "falling".

So "technically" your above paragraph is wrong.

Remember "rock and a hard place".

 

[pgimeno]

A lot of "debunkers" seem to specialize in vague and imprecise language and dodging plainly spoken, direct questions.

I can only assume it's to mask that

1) they don't really have a clue what they pretend to have a clue about, or
2) they have a clue but know that what they are arguing is indefensible so they mumble vaguenesses, clichés and platitudes, use bizarre, broken logic, and/or hurl insults and accusations in the hopes that you will be too distracted to see the gaping holes.

Says the pot to the kettle. You're accusing the people who participate here of doing what you are doing. Please address post #368 instead of dodging it every time I ask. It's central to make you understand how wrong you are. If you agree that the top reaches the street level intact, then you are accepting that the crush-down/crush-up model is accurate. If you don't agree, it shows you're wrong in your belief that rubble is not able to crush. That's probably why you're dodging it.

And the question stated in that post is also relevant to understand why it's irrelevant that the top is intact or is in the form of rubble: what significant difference would it make for the rubble layer to be driven by an intact upper block or by more rubble?

You can dodge, but you can't escape.

And here's another new question for you, this one about pure physics:

You say that a bowling ball in pieces wouldn't have the same kinetic energy or momentum as a whole bowling ball (I assume you mean with the same total mass and velocity).

Please give a quantification of it in this simplified example: imagine a bowling ball split in half, with the two halves moving together.

1. How much energy do the combined two halves do, as compared to a whole ball?

2. Assuming you can survive an impact of half a bowling ball but not a whole bowling ball, would you survive an impact of the two halves together?

 

[ergo]

Each piece of debris was torn loose from the structure of the building and ended its 'career', so to speak, in an inelastic collision with the ground (or the rubble pile).

Much of the debris is in the form of dust, as we can see by the dust plumes in the pictures and that then covered Manhattan for days afterward, and as evidenced by the absence of larger chunks of matter at Ground Zero that one would normally find in natural collapses. That dust did settle of course, but it was not part of the "falling" debris that you are trying to include in this discussion of mass, and I don't think there has been an accurate estimate of how much of the buildings were converted into this dust, or what I like to call powder. Just sayin'.

Large amounts of other debris, as we know, fell outside the building, yes, landing on the ground, outside the building's footprint.

That's a given - as I said, I'm just trying to lay out a scenario in which we can come to a consensus about the physics right now. One question from earlier that you did not answer: do you agree that two objects or groups of objects with the same mass traveling at the same speed have the same kinetic energy?

I will agree that two objects with the same mass traveling at the same speed will have the same momentum. I am not clear in this example of how momentum would be distinct from kinetic energy. I also don't see the point of bringing into the discussion "groups" of objects. Just discuss the objects on their own.

While the total energy of a system is only conserved if the system is isolated, every instance of work conserves energy while converting it from one form to another or transferring it from one place to another.

Okay.

 

[ergo]

And the question stated in that post is also relevant to understand why it's irrelevant that the top is intact or is in the form of rubble: what significant difference would it make for the rubble layer to be driven by an intact upper block or by more rubble?

The properties of rubble. How it moves and how it behaves when encountering resistance, as compared to an intact block of storeys. Because it is in many different pieces, i.e., not held together by anything, rubble "falling" on top of a building will mostly flow over and outside it, not through it, except perhaps for some larger chunks. Rubble also cannot stay vertical as a mass for any significant length of time. The top of the rubble pile always flows down to the sides. That darn gravity again.