Moderated Continuation - Why a one-way Crush down is not possible

[Justin39640]

Yes. Why would it not?


A lead bullet flying only slightly faster than 500MPH can punch through steel about as thick as what the exterior beams on the upper floors of WTC were made of. Lead is much softer than aircraft alloy aluminum.

i think if that plane was made of balsa wood it would have still mangled the columns at that speed

 

[Gamolon]

A rigid body is just an approximation of the real thing using worst case assumptions.

Right.

What I am trying to get at is that Heiwa and Bill are saying that the upper part of the tower cannot be considered a rigid body. What I want to know is what then, in Heiwa's and Bill's minds, constitutes a rigid body? If the upper portion of the tower doesn't meet their definition of a rigid body, what does?

 

[ferd burfle]

Suppose the plane was hanging statonary in the sky and you flew he building at the aluminium plane at 600 mph do you really think the plane would smash through 33 well braced steel box-columns , go on to destroy 10 massive core columns and partially exit the building through perhaps a dozen more steel box columns ? The physics are exactly the same . Don't rush to answer.

If I don't rush, it's only because I'm boggling at the sheer ignorance of this. You really don't understand that the result is the same, regardless of which body is moving? In answer to your question, yes, that's exactly what happens.

Or do you think the 500,000 ton building would swat the 150 ton plane from the sky ?

And from this we discover the true source of your physics knowledge....Roadrunner cartoons.

ferd

 

[bill smith]

If I don't rush, it's only because I'm boggling at the sheer ignorance of this. You really don't understand that the result is the same, regardless of which body is moving? In answer to your question, yes, that's exactly what happens.



And from this we discover the true source of your physics knowledge....Roadrunner cartoons.

ferd

I read you loud and clear,

 

[carlitos]

If I don't rush, it's only because I'm boggling at the sheer ignorance of this. You really don't understand that the result is the same, regardless of which body is moving? In answer to your question, yes, that's exactly what happens.



And from this we discover the true source of your physics knowledge....Roadrunner cartoons.

ferd

But ferd, when you hurl a knife at a guy it stabs him. Conversely, when a guy falls into a knife ... Oh, wait, it's the same.

 

[Gamolon]

Suppose the plane was hanging statonary in the sky and you flew he building at the aluminium plane at 600 mph do you really think the plane would smash through 33 well braced steel box-columns , go on to destroy 10 massive core columns and partially exit the building through perhaps a dozen more steel box columns ? The physics are exactly the same . Don't rush to answer.

Or do you think the 500,000 ton building would swat the 150 ton plane from the sky ?

Well, your man Heiwa seems to think it's possible for the plane to smash through the steel perimeter columns. Here is a personal message he sent me some time ago (bolding mine).

Let's look at a collision between the 350x350x12.5 mm vertical steel column (the bread) and a aluminium wing profile consisting of two plates say each 4 mm thick and 3000 mm wide (the knife) with variable distance between the plates.

Or, say, can ju cut a 350x25 mm (8 750 mm²) steel plate with a 3000x8 mm (24 000 mm²) alu plate.

The steel is 3X denser/stronger than the aluminium.

At contact the pressure must have been quite big, evidently both objects fracture at very high temperature ... and are cut in pieces. It goes very quick.

So I think it is possible. But it would have been interesting to see the fracture surfaces of the columns.

At the wing tips and where the wing profile hits a rather thick floor, you should wonder what happens.

If a wing tip cannot cut the column, the wing tip would bounce or get stuck. Same when hitting a floor. But as the bouncing pieces are still connected to structure with forward motion hitting nothing maybe everything just continues into the tower.

This is no big deal for me. The steel towers could never be crushed down later. It is obvious CD. That's easy to show. And I don't believe a word of the 911 Commission report. 19 arabs? Come on. No chance!

br

Heiwa

Are you going to question Heiwa's post now? Are you going to argue with him that it's absolutely not possible for the plane to smash through the perimeter columns?

 

[FineWine]

Suppose the plane was hanging statonary in the sky and you flew he building at the aluminium plane at 600 mph do you really think the plane would smash through 33 well braced steel box-columns , go on to destroy 10 massive core columns and partially exit the building through perhaps a dozen more steel box columns ? The physics are exactly the same . Don't rush to answer.

Or do you think the 500,000 ton building would swat the 150 ton plane from the sky ?

So, Bill, you started to watch Mackey's lecture explaining how the planes entered the buildings and something happened. Did someone flick the "off" switch in your brain? You have gone to great lengths to show us that you have absolutely zero self-esteem, but your death-throes are downright unpleasant. Some of us are capable of finding out exactly what perimeter and core columns were damaged by the planes. You can't, but that's your problem. In the meantime, please spare us this hopeless insanity. A hand can still break a brick (quick--tell us how); a bird can damage a titanium fan blade; water can cut steel. No matter what Ace Baker and Jim Fetzer and Morgan Reynolds say, those assertions will always be true and those idiots will always be wrong. The no-planers are the sickest psychos in the world.


In your inept example, swatting the plane with the building would destroy the plane totally, just the way it happened in reality (there's that word you hate so much). And the plane would damage the building.

You can't win, Bill.

 

[bill smith]

Well, your man Heiwa seems to think it's possible for the plane to smash through the steel perimeter columns. Here is a personal message he sent me some time ago (bolding mine).



Are you going to question Heiwa's post now? Are you going to argue with him that it's absolutely not possible for the plane to smash through the perimeter columns?

No on this I do not agree with Heiwa. If the columns had been solid 1/2'' steel then just maybe. But these were BOX-COLUMNS and braced at 12 foot intervals against the concrete floors. The columns may have been only 14'' wide but hey were also 14'' DEEP and would have made perfect shock absorbers as they crushed. No chance.

 

[Dave Rogers]

The columns may have been only 14'' wide but hey were also 14'' DEEP and would have made perfect shock absorbers as they crushed.

Amazing. He almost sounds like he knows what the words mean.

Dave

 

[tfk]

Gamolon,

A couple of comments...

I love T's definition.lol. 'A body can be considered rigid until an outside forcre acts on it' (paraphrased) Think of standing on a marshmallow. lol

If you bother to go back & look, you'll see that Bill's "paraphrase" of my definition bears zero resemblance to what I really said.

Bill knows this, of course. This is his little game.

So can you provide me of a real world example of a rigid body?

As everyone & their sister (at this point) has explained, a rigid body is a mathematical approximation. An idealization.

My take on this is from the perspective of a mechanical, not structural, engineer. Most of the time, structural engineers frown on their constructions (buildings, bridges, etc) doing a whole lot of jumping around. Our stuff moves around a lot. And the same piece that can be considered rigid at small accelerations can become amazingly non-rigid at higher ones. Hence statics vs. dynamics.

I've tried to get across in the past that the concept of a RB is a TOOL in the hands of a physicist, a structural or mechanical engineer or simulations modeler. And like all tools, it's a very useful when used correctly. And a bludgeon if used by a hack. (Not always, tho. Sometimes you want a bludgeon.)

The fine point is that, whether or not something can be appropriately modeled as a rigid body does NOT depend only on the object. It depends on the type of analysis that you're trying to do.

A semi truck being weighed on scales can be considered a rigid body.

The same semi truck driving off of a cliff can be considered to be 2 rigid bodies (cab & trailer) during its flight thru the air. This does NOT mean that the modeler asserts that it will not deform when it hits the ground. (This is very similar to the WTC model.)

The same semi truck can NOT be considered to be a rigid body if you are trying to model its shock & vibration response while driving down the highway.

A water balloon thrown thru the air, vibrating and oscillating like crazy (like those Pixar animation gum drops) CAN be considered to be a rigid body IF your only interest is "what is the path of the CG of the balloon?"

So, while a strict definition of the term can require no relative motion between the components, I stand by a looser definition. If the internal deflections are irrelevant to what I am trying to model, then I can consider any part, no matter how flexible or inflexible, to be a rigid body.

Of course, if you REALLY need a rigid body in real life, you specify that it be made from "unobtanium".

Tom

 

[Gamolon]

No on this I do not agree with Heiwa. If the columns had been solid 1/2'' steel then just maybe. But these were BOX-COLUMNS and braced at 12 foot intervals against the concrete floors. The columns may have been only 14'' wide but hey were also 14'' DEEP and would have made perfect shock absorbers as they crushed. No chance.

Do you have the math to back up the fact that the perimeter columns and 4" think concrete floors should have resisted the plane impact?

Are you saying that Heiwa's calculations are incorrect? Can you show me where?

 

[FineWine]

Do you have the math to back up the fact that the perimeter columns and 4" think concrete floors should have resisted the plane impact?

Are you saying that Heiwa's calculations are incorrect? Can you show me where?

In the second show of his three-part lecture on the physics of 9/11, Ryan Mackey showed the math behind the plane's penetration of the building. Bill said he would watch, but he either lied again, or couldn't understand a word.

 

[Heiwa]

As everyone & their sister (at this point) has explained, a rigid body is a mathematical approximation. An idealization.

Edited by Gaspode: 

Removed breach of Rule 12

Since when is a rigid body a mathematical approximation? I thought math was exact. Or is it just rigid rubble? Your idealization?

I like your 'the same piece that can be considered rigid at small accelerations can become amazingly non-rigid at higher ones'. Is that your rubbish in reverse?

And your "The fine point is that, whether or not something can be appropriately modeled as a rigid body does NOT depend only on the object. It depends on the type of analysis that you're trying to do."

When will we see your rubble getting compacted crushing anything analysis being published?

Or was it just done?

Yes it was! "A water balloon thrown thru the air, vibrating and oscillating like crazy CAN be considered to be a rigid body"!!

LOL

 

[Gamolon]

Edited by Gaspode: 

Removed breach of Rule 12

Since when is a rigid body a mathematical approximation? I thought math was exact. Or is it just rigid rubble? Your idealization?

I like your 'the same piece that can be considered rigid at small accelerations can become amazingly non-rigid at higher ones'. Is that your rubbish in reverse?

And your "The fine point is that, whether or not something can be appropriately modeled as a rigid body does NOT depend only on the object. It depends on the type of analysis that you're trying to do."

When will we see your rubble getting compacted crushing anything analysis being published?

So what type of structure or object can the term "rigid body" be applied to in your mind?

This should be good...

 

[Gamolon]

Yes it was! "A water balloon thrown thru the air, vibrating and oscillating like crazy CAN be considered to be a rigid body"!!

LOL

So now have the upper portion of the tower and a water balloon as things that cannot be a rigid body.

Can you please provide an example of what you think would fit the term?

 

[Gamolon]

Taken from Heiwa's site:

All these assumptions, apart from being ridiculous, are false. A rigid body, an upper part C, does not exist! By definition a rigid body destroys anything non-rigid it touches. But the upper part C is destroyed before the destruction of the lower structure commences.

I thought your definition said that a rigid body was an idealization? Why are you implying above that a rigid body exists in some physical form and should destroy anything non-rigid?

Have an example of that rigid body yet?

 

[tsig]

Suppose the plane was hanging statonary in the sky and you flew he building at the aluminium plane at 600 mph do you really think the plane would smash through 33 well braced steel box-columns , go on to destroy 10 massive core columns and partially exit the building through perhaps a dozen more steel box columns ? The physics are exactly the same . Don't rush to answer.

?

Yes.

 

[bill smith]

Yes.

The jref gets a mention at the beginning of this interview between Frank Greening and Kevin Barrett. Very very interesting. Frank is one of your guys wasn't he ?
http://www.internationalskeptics.com/forums/showthread.php?p=4970586#post4970586

 

[Newtons Bit]

Taken from Heiwa's site:



I thought your definition said that a rigid body was an idealization? Why are you implying above that a rigid body exists in some physical form and should destroy anything non-rigid?

Have an example of that rigid body yet?

Just an FYI, rigid bodies don't DESTROY things that they touch. Rigid bodies just don't deform when there is a force acting on them. What this means it that it's very simple to calculate how an object moves when an outside force acts on it.

A rigid body could collide with a spring and then get thrown off (this is how freshman physics addresses springs).

Heiwa just likes to make things up.

 

[newton3376]

Since when is a rigid body a mathematical approximation? I thought math was exact.

How can you say stuff like this?