Acceleration of the falling top blocks.

[Furcifer]

As a scientist, I have considered this at great length. The main focus of mine for the last ten years has been an answer to the question, "What destroyed the World Trade Center?"

Funny, so did hundreds of scientists with actual expertise in buildings and materials. Who to believe? Who to believe.

 

[nomuse]

The fruit story is logical and makes sense, but you're forgetting that the WTC structure was not made of cardboard. It was made of steel, which is extremely strong.

Do you understand scaleability? The square-cube law?

At the relatively low speeds that gravity alone would produce, a twelve foot fall (as the gravity collapse model says was the initiator), would not produce a force strong enough to collapse lower floors.

Gravity is a force, which causes acceleration -- not a speed.

If you drop an object from the top of our atmosphere, it would land (ignoring air resistance) at around ten kilometers per second velocity.

And although MV = MV, Ke = 1/2MV^2. That Ke goes up FAST as the distance fallen increases.

This didn't happen, of course. I'm just saying that in the theoretical universe that the upper twenty floors fell twelve feet and hit the lower floor of the WTC, it probably would have held. It absolutely would have significantly slowed the descent of the upper floors, had this happened, which it didn't.

Okay, this is what you expect. That's fine; a lot of people have naive expectations about how objects and forces outside of their direct experience behave.

But you want to do science? You don't go with untested gut assumptions. YOU CALCULATE.

If you don't do the numbers and TEST how you think the behavior should happen, you aren't even doing cargo cult science. You just plain aren't doing it.

 

[ergo]

Twenty four seconds? Really?

The 9/11 idiot movement is always scrounging around for extra seconds in their collapse descent times. From the WTC 7 east penthouse to the lingering remnant of Twin Tower cores that held up for a few seconds after the buildings collapsed, they are desperate for that extra time it takes to pick your nose to try to somehow "prove" that the buildings didn't plummet to the earth in under 15 seconds. But of course even they can't agree amongst themselves, lol.

The descent time is really the measurement of the so-called "falling top blocks" from their starting point to hit the ground, as they theoretically (but impossibly) descend through the rest of the building. 12 seconds is about right.

 

[ergo]

Anyone still defending the gravity collapse model at this point is a moron or a liar. We know who the liars are. This is pre- high-school level physics.

 

[thedopefishlives]

Anyone still defending the gravity collapse model at this point is a moron or a liar. We know who the liars are. This is pre- high-school level physics.

That explains why you don't understand it.

 

[Furcifer]

Anyone still defending the gravity collapse model at this point is a moron or a liar. We know who the liars are. This is pre- high-school level physics.

No fooling, the towers stood for 20 some years without gravity making them collapse.
Everyone knows it's the fire damage that caused the towers to collapse. It's simple physics.

 

[000063]

The fruit story is logical and makes sense, but you're forgetting that the WTC structure was not made of cardboard. It was made of steel, which is extremely strong.

At the relatively low speeds that gravity alone would produce, a twelve foot fall (as the gravity collapse model says was the initiator), would not produce a force strong enough to collapse lower floors. This didn't happen, of course. I'm just saying that in the theoretical universe that the upper twenty floors fell twelve feet and hit the lower floor of the WTC, it probably would have held. It absolutely would have significantly slowed the descent of the upper floors, had this happened, which it didn't.

Someone did the math. The upper floors hit with about six times the mass of the entire tower. I don't know how you expect the lower section to withstand that.

 

[000063]

The 9/11 idiot movement is always scrounging around for extra seconds in their collapse descent times. From the WTC 7 east penthouse to the lingering remnant of Twin Tower cores that held up for a few seconds after the buildings collapsed, they are desperate for that extra time it takes to pick your nose to try to somehow "prove" that the buildings didn't plummet to the earth in under 15 seconds. But of course even they can't agree amongst themselves, lol.

If large portions of the building still stood, then by definition the building has not "totally collapsed".

The descent time is really the measurement of the so-called "falling top blocks" from their starting point to hit the ground, as they theoretically (but impossibly) descend through the rest of the building. 12 seconds is about right.

Ah. Moving the goalposts. Got it.

Found any evidence of barotrauma yet? Blown-out windows? Audio evidence of explosions consistent with explosives? Explained why explosives were in WTC 7 in the first place? Because in the scenario you're proposing, there would've been highly noticable explosions going off throughout the towers during the collapse. Where's the video of that? How did people who were inside the towers survive?

Anyone still defending the gravity collapse model at this point is a moron or a liar. We know who the liars are. This is pre- high-school level physics.

This coming from the man who once scoffed at someone using elementary-school physics to determine time of day by shadows, and has gotten less and less likely to actually respond to posts with any substantial points.

 

[thedopefishlives]

Someone did the math. The upper floors hit with about six times the mass of the entire tower. I don't know how you expect the lower section to withstand that.

One of our resident Truthers - was it ergo? - stated that they didn't think the Towers would collapse even if a "moon-sized field of rubble" was dropped on them. That should tell you all you need to know about their expectations.

 

[WTC Dust]

Responses in red.

How much does one floor hold? Can it hold 12 floors? Do some research before making up silly fantasy answers out of thin air.

The 1st floor was strong enough to hold 109 upper floors. The 2nd floor was strong enough to hold 108 upper floors. Etc. Was this the answer you were looking for?

What kind of aircraft impact were the towers designed to resist?

The kind made of an aluminum frame carrying jet fuel.

You have no idea because you failed to talk to Robertson the person who took did the design. He made it for a slow moving 707 lost in the fog low on fuel. The only rational accident that could happen, the one you never thought of. The design was verified by a study, it the WTC steel exterior was 1/2 inch, the 911 planes would have been stopped.

Huh?

Design of WTC impact by a plane 187 pounds of TNT in kinetic energy.
Flight 11, 1300 pounds of TNT in kinetic energy, oops too much.
Flight 175, 2093 pounds of TNT in kinetic energy, 11 times too much.

Both Twin Towers withstood the initial "hit" of damage, whatever it was. You say it was a plane crash. I say this is 100% incorrect, but even if it was correct, both buildings stood tall after the initial damage. 56 minutes. Standing tall. Then WTC 2 goes away. 102 minutes. Standing tall. Then WTC 1 goes away. You say this had something to do with a plane crash? Seriously? This "plane crash" as you call it, was long over. The only thing you had left after 56 and 102 minutes was some buildings standing there, looking like they were on fire. Then POOF! Metallic foam is produced from steel and concrete buildings. Why do you speak of such silliness as plane crashes or 11 times bigger plane crashes?

You failed to think before you make up your fantasy.

The truth is that I have obsessed about 9/11 for years. There's nothing I want to figure out more than this, and there's nothing this big and this important that I've ever worked on. Yeah, I've given this a bit of thought.

You don't understand physics or structural engineering, you don't know any facts about 911 or the WTC towers.

You are not clairvoyant, and you should be embarrassed as having presented yourself as such on the James Randi forum.

You don't understand momentum. You have no clue how long it took the towers to fall.

More clairvoyance? A shame.

 

[carlitos]

One of our resident Truthers - was it ergo? - stated that they didn't think the Towers would collapse even if a "moon-sized field of rubble" was dropped on them. That should tell you all you need to know about their expectations.

A classic. That was in reply to me.

Mr. Third Law, please answer the question. You keep insisting physics agrees with you. Show it.

* A speck of rubble, dropped from z height, will not initiate the collapse of the WTC tower.
* A pound of rubble, dropped from z height, will not initiate the collapse of the WTC tower.
* X tons of rubble, dropped from z height, will not initiate the collapse of the WTC tower.
* Y tons of rubble, dropped from z height, will initiate the collapse of the WTC tower.

(Y is assumed to be greater than X in the above)

I agree that Y tons of rubble may have the power to crush through or partially destroy a floor or floors below it.

Everyone here reading this can understand my point. At some point, you will reach enough rubble that it would crush the remaining floors of the WTC. You can pretend not to understand, but even you realize that a moon-sized field of rubble, dropped from some height, would crush a skyscraper.

I'm not sure even a moon-sized field or mountain of rubble, dropped from a height of 12 feet would entirely crush the WTC. No. If you had it coming down from a higher height, in a steady stream over a long period of time, we would certainly see some major damage. Total collapse? I'm not sure.

Assuming whatever height z, what is your calculation for Y above? How much energy would it need to generate? How much energy did the upper block apply on the floor below it? Why wasn't this enough to initiate collapse?

Because the buildings had inherent load-absorbing capacity, like any modern highrise. When force is coming from above, it is referring ultimately through the entire structure. It would take a much greater force, from a much greater height to "crush" the building. Gravity cannot do it, because the building's design prevents it, as do all modern highrise designs.

Mass of the moon = 7.3477 × 10²² kg
Mass of the upper floors that fell 12 feet = a bit lower than that

 

[phunk]

Responses in red.

When you put your responses inside someone else's quote, it means we can't use the quote function to reply to you. Don't do that.

 

[phunk]

The 1st floor was strong enough to hold 109 upper floors. The 2nd floor was strong enough to hold 108 upper floors. Etc. Was this the answer you were looking for?

This is incorrect. The floors were only built to hold their own contents. NONE of the weight of the floors above them were held by the floors, that weight was all attached to the core and perimeter columns.

If the upper block started to fall, the only way it could be "caught" by the building below it is for the columns of the upper block to somehow remain perfectly aligned with the columns below, and land perfectly on top of them. This became impossible as soon as the upper block began to tilt.

 

[ergo]

This is incorrect. The floors were only built to hold their own contents. NONE of the weight of the floors above them were held by the floors, that weight was all attached to the core and perimeter columns.

If the upper block started to fall, the only way it could be "caught" by the building below it is for the columns of the upper block to somehow remain perfectly aligned with the columns below, and land perfectly on top of them. This became impossible as soon as the upper block began to tilt.

Leaving aside the obvious problem of what happens to the falling upper section of building in this case, please tell us what officially endorsed floor failure collapse model you are citing here. What peer-reviewed engineering analysis that NIST didn't throw out describes this floor failure model? Thanks.

 

[phunk]

Leaving aside the obvious problem of what happens to the falling upper section of building in this case, please tell us what officially endorsed floor failure collapse model you are citing here. What peer-reviewed engineering analysis that NIST didn't throw out describes this floor failure model? Thanks.

I'm not citing any official model other than the design of the building. The floors were not attached to each other, they were only attached around their edges to the columns. The floors could not hold the whole building above them, this is a trivial fact. I know you've seen the pictures of the truss seats hundreds of times on this forum, do I really need to show them again?

It also shouldn't require an "official collapse model" for you to realize that if you break a column, the upper section can't hold up any load unless it's sitting on something that can hold just as much load. So it either has to land on top of the lower section again, or there needs to be something else it can land on that can hold it up. What do you propose could do that? Do you think the beams that horizontally stabilize the columns could bear that kind of vertical load? There isn't much of anything else the core columns could land on, and there's literally nothing else for the perimeter columns to land on.

 

[ergo]

I'm not citing any official model other than the design of the building.

So you're just making an amateur guess? That's fine, as long as you acknowledge this, and acknowledge that your amateur guess is not part of an engineering peer review.

I know you've seen the pictures of the truss seats hundreds of times on this forum, do I really need to show them again?

Actually, what we've seen is a spammed image that shows the floors under construction. An image that also seems to want to give the impression that the floors were precariously flimsy and that the steel cabling in the trusses is something in the order of less than an inch thick. What isn't shown in that spammed image are the bridging trusses and the complete assembly that secures the floor panels to the columns.

It also shouldn't require an "official collapse model"....

... for you to realize that if you break a column, the upper section can't hold up any load unless it's sitting on something that can hold just as much load.

This is nonsensical. Do you understand what you're saying?

So it either has to land on top of the lower section again, or there needs to be something else it can land on that can hold it up. What do you propose could do that? Do you think the beams that horizontally stabilize the columns could bear that kind of vertical load? There isn't much of anything else the core columns could land on, and there's literally nothing else for the perimeter columns to land on.

I don't think you understand your own argument.

 

[phunk]

So you're just making an amateur guess? That's fine, as long as you acknowledge this, and acknowledge that your amateur guess is not part of an engineering peer review.

Just like yours.

Actually, what we've seen is a spammed image that shows the floors under construction. An image that also seems to want to give the impression that the floors were precariously flimsy and that the steel cabling in the trusses is something in the order of less than an inch thick. What isn't shown in that spammed image are the bridging trusses and the complete assembly that secures the floor panels to the columns.

How does an image "want to give an impression"? The floors weren't flimsy, they were perfectly designed to carry their own load. This doesn't change the fact that they were long spans only supported at the edges and not designed to support the building above them. There is plenty of available documentation of the connections between the trusses and columns if you cared enough to look.

This is nonsensical. Do you understand what you're saying?

How is it nonsensical? How much load can a column with nothing under it support? Did they install hovercolumns in the wtc?

I don't think you understand your own argument.

Clearly, YOU don't understand my argument. What is going to hold up all of the columns of the upper block of the building once it tilts a little and the columns are no longer aligned with the columns in the building below?

 

[DGM]

Actually, what we've seen is a spammed image that shows the floors under construction. An image that also seems to want to give the impression that the floors were precariously flimsy and that the steel cabling in the trusses is something in the order of less than an inch thick. What isn't shown in that spammed image are the bridging trusses and the complete assembly that secures the floor panels to the columns.

So I take it you can show us this in plan? Why don't you just admit you have no clue how the building was constructed and save time. Why do you think you can find the truth by making crap up?

 

[NoahFence]

The 1st floor was strong enough to hold 109 upper floors. The 2nd floor was strong enough to hold 108 upper floors.

Dusty, of all the absurd statements you make, this one might take the cake.

 

[NoahFence]

So you're just making an amateur guess? That's fine, as long as you acknowledge this, and acknowledge that your amateur guess is not part of an engineering peer review.

To rational, sane, and honest people, not everything requires a model. Some things are as obvious as the nose on your face. This is one of those things. And you're not one of the sane, rational or honest people who can see it. That's on you.