New guy here: Questions for official hypothesis

Sizzler said:
If it isn't a single unit, how can it have a single unit measurement of KE?
I understand that it might still cause the floors to collapse, but not as fast as Bazant predicted.
This is a fair statement.
If the falling mass is not together, how can the mass of the building be born at its front?
If I pour a 20 pound bag of sand on a scale it will take more time to read "20 pounds" than if I just put that bag on the scale.
Do you get it?
Thus Bazants fall times are incorrect.
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You flunked physics! Tell the truth!

Bazants fall times are very good. You on the other hand...
 
WildCat said:
Ayup.... :rolleyes:
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What is so hard to understand?

When a falling mass of several units hits something, the applied KE to that something would be progressive.

When an equal falling mass of one unit hits something, the applied KE to that something would be more immediate?

No?
 
Sizzler said:
Bazant's model has the falling mass as a single unit. Thus the KE of the falling mass is realized at the front of this mass.

In reality, the upper block would have broken up, this would change the nature of the KE and thus the time of the fall.

Therefore, isn't Bazant's fall time totally wrong?
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You're assuming that Bazant's fall time is wrong -- and thus, demonstrating that you haven't understood anything at all.

There are several relevant Bazant papers: Bazant & Zhou (2002), Bazant & Verdure (2006), and Bazant, Le, Benson, and Greening (2007, in press). The discussion here seems to have been on the first paper, though it doesn't contain much discussion of timing -- it's about the likelihood of collapse.

The latter two papers do discuss timing, and their calculations match the observed results.

Get that? They match. So if there's an error, why do they get the right timing?

Your arguing that something should affect the timing doesn't answer this question. You have to show that it does. That is going to take far, far more knowledge than you've displayed. And you'll probably find that your intution is wrong, as it is in this case.

In other words, you're not asking a question. If you want to learn, ask real questions. Otherwise, be ignored. Other people have given you all you need to learn, but you haven't followed up on it, so why should we bother?
 
Jonnyclueless said:
Were there sacks involved? Yes. not actual sacks, but the sack in the analogy is the mechanism that keeps the rocks interacting with each other so they operate in some ways as a whole, and in some ways not. Same with the building top. It's not just a solid object, and it's not a million pieces each acting without influence from each other. It's more complex than you are thinking.

but this at least makes it more understandable as to where you are misunderstanding things.
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Someone back said the upper falling section would have broken up, but the total mass is the same.

I understand that.

But it isn't a single unit anymore. Thus KE is changed. Thus fall times are changed.

No?

Please explain why.
 
R.Mackey said:
You're assuming that Bazant's fall time is wrong -- and thus, demonstrating that you haven't understood anything at all.

There are several relevant Bazant papers: Bazant & Zhou (2002), Bazant & Verdure (2006), and Bazant, Le, Benson, and Greening (2007, in press). The discussion here seems to have been on the first paper, though it doesn't contain much discussion of timing -- it's about the likelihood of collapse.

The latter two papers do discuss timing, and their calculations match the observed results.

Get that? They match. So if there's an error, why do they get the right timing?

Your arguing that something should affect the timing doesn't answer this question. You have to show that it does. That is going to take far, far more knowledge than you've displayed. And you'll probably find that your intution is wrong, as it is in this case.

In other words, you're not asking a question. If you want to learn, ask real questions. Otherwise, be ignored. Other people have given you all you need to learn, but you haven't followed up on it, so why should we bother?
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so help me with this then

quoted from above:
Bazant's model has the falling mass as a single unit. Thus the KE of the falling mass is realized at the front of this mass.

In reality, the upper block would have broken up, this would change the nature of the KE and thus the time of the fall.

Therefore, isn't Bazant's fall time totally wrong?
Click to expand...
 
R.Mackey said:
I've been watching this with a mounting sense of dread... perhaps there's a Sticky Note that indicates where this thread went from "I'm new and I have questions" to "I have all the answers to YOUR questions."

This may sound cruel, but those of us familiar with the science have few to no outstanding questions about the inevitability of total, progressive, vertical collapse in ~ 15 seconds for both WTC 1 and 2. And if we had questions, we'd ask professors and scientists who have looked into the problem. This individual would certainly be well down the list of who to ask, even overlooking his apparent total grasp of the physics from zero in, oh, about 300 posts...

To Sizzler, if you have legitimate questions, feel free to ask. But do not ask questions that are merely veiled assertions. Those are non-starters.
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Challenged with physics; Maybe his physics was not engineering first year physics but some physical science class that allowed him to pass even though he does not understand any real physics. Could be a kid in high school, or in grade school. He has a lot of time to post, he could be Dylan, Ross, or some other truther acting dumb. Why do they always claim a basic understanding of physics and then post stundie quality examples.

nice post
 
R.Mackey said:
Sure.

"Changed the nature of KE" is nonsense. That's why you're wrong.

Easy.
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Why is it nonsense?

If I drop a bucket with sand in it, the mass is a single unit.

If I drop the sand without the bucket, the mass is not a single unit.


The KE of the sand in the bucket is applied at once.

The KE of the sand without the bucket is applied more progressively.

In the end, the KE is the same, but its application to another object is different.

Where did I go wrong with this?
 
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Sizzler said:
Why is it nonsense?

If I drop a bucket with sand in it, the mass is a single unit.

If I drop the sand without the bucket, the mass is not a single unit.


The KE of the sand in the bucket is applied at once.

The KE of the sand without the bucket is applied more progressively.

In the end, the KE is the same, but its application to another object is different.

Where did I go wrong with this?
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It's nonsense because you don't even have the vocabulary to discuss it correctly.

The correct verbiage is pressure and impulse. The first refers to the average force imparted during the impact, and the second refers to the net change in momentum applied.

Because of the sheer enormous scale and the inelastic nature of the upper block impact, it is more important to consider the total momentum of the problem than the energy. The upper block isn't going to instantly bounce off, nor are chunks of it going to do so. Even if heavily fragmented, we're talking about awfully big chunks. So that means we are dealing with an inelastic situation, i.e. things tend to stick together, and dissipate additional energy by damaging each other.

Since it's inelastic, the pressure isn't as important. The impulse is what matters. And impulse does not care whether it hits all at once, or in chunks. The only exception would be if the chunks were so small that each impact could be considered elastic, and if it happened over such a long time period that the average force did not exceed the elastic limits of the objects hit. Neither condition is true. Therefore, it doesn't matter whether it hits in one piece or many.

For a much more rigorous treatment, please actually read Bazant's papers, and check the ego at the door. You are starting at the extreme beginning of Newtonian mechanics. Throw out everything you think you know, and do your best.
 
Sizzler said:
Look above at my sand example.

What is wrong with what I said?
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Whether you calculate the KE of one large piece, or many small pieces of equivalent mass, the total energy is the same. You got that right. You question that this energy was sufficient to cause collapse. This is your error because the building is no longer there. Get it? The structure collapsed ergo, you are wrong.
 
Sizzler, do you believe from watching the videos that the towers needed explosives to fall as they did?
 
Sizzler, how many times must it be stated till you get it? We have several strutural engineers EXPLAININg that an 8th grade student can "get it".

Why haven't you bothered to contact Bazant? Stop dilydalying, since YOu apparently dont like our answers.

Contact Bazant, and come back when you have HIS answer.
 
So he went from being a "bit confused" about the collapse mechanism and requesting sources:

Sizzler said:
Thanks for the info guys.

I am a bit confused with the current hypothesis for 'complete' or 'global' collapse mechanism.

Can someone link me to a scientific paper that describes a global collapse theory after collapse initiation?

What is the leading theory and paper on this?
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...To saying the current theories are "garbage"...

Sizzler said:
Bazants purpose was to show fall time and full progression are expected.

If the top part breaks to pieces, this changes his model, and thus his fall time.

Thus the fall times do not equal what we really saw in reality.

Thus his model is garbage. It is no better than saying it was hit by laser beams.
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...in a couple of days.

Amazing he was able to study the subject, understand it fully, and dismiss it as "garbage" in 48 hours. Especially starting from such an unbiased, objective position as he so cleary was when he began this discussion.
 
Like i stated in earlier posts, sizzler's presence here stinks of a truther in disguise. He writes like Max Photon (a carriage return after every sentence).

he's now on ignore. Since he wont listen to the experts here, and WONT attempt to contact Bazant, who's paper he is criticizing, its easy to see that he is not here for the "truth" at all. And not "confused".

48 hours, and he's only read Bazant's paper? On the first page, tehre are links to 20 different reports. NIST's report takes at least a 2 week read.
 
Let me try this again.

I'm sorry I am not using the right words. To be clear, I have first year uni physics (I did not do well of course:) ) but I do have a degree in Biology.

With that said, you guys are the experts (some of you) and I am the layman.

So.

In Bazants model, the upper falling block in the beginning has a single mass. It is a single unit moving as one. It has a single unit of KE.

But, when the dust clears after the collapse, the core remains for a bit. This means that the core (lower part remaining) must not have been crushed by the falling block.

This means that the block must have fallen apart at some point.

The collapse was chaotic, so why should I believe that the mass of the broken block remained as one? Parts of that block would have been deflected.

Even if all parts of the block remained inside the footprint, due to deflection and differing masses of the broken pieces, the broken pieces wouldn't have fallen as one mass of many pieces together. Certain pieces would have hit the next floor before others.

Thus this changes the amount of KE initially applied to each floor after the block broke. This would then slow the collapse down and perhaps not cause it to completely collapse.

There is a reason he drew the block intact at the end of the collapse (just before crush up with the ground) in his pictures and ignored the remaining core.

I think the reason is because it would have changed his results.
 
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