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

[newton3376]

Not in this case. The lightest one-tenth of a building has never in recorded world history crushed down the other nine-tenths of the same building. Plain common sense is enough to spot the con.

So if something has never happened before...then it can never happen.....

Great logic there Bill.

If you told me that we have examples of buildings of the same construction style as the WTC that were hit with similar airplanes, at a similar speed, at a similar location, and had similar multi-story fires burning and that none of those buildings fell the way the WTC did then I might say you have a point...

But alas, you don't.

To be blunt scientists and engineers don't CARE what YOU think.

 

[bill smith]

Based on what I see quoted, the timeout idea is an excellent one. If not that, perhaps Bill could clarify his idea about the planes / no planes / hurricane-powered laser beams in this topic?

I think you meant this thread Carlitos.Post 554 and some either side of that.
http://www.internationalskeptics.com/forums/showthread.php?t=144954&page=14

 

[tsig]

Bad Boy you are thinking pretty clearly it seems. Just do not accept any rubbish you are told as gospel. Trust yourself and your instincts.

That's always better than learning something.

 

[ferd burfle]

Well for the reasons I gave in the post you reference I find it impossible to believe that the fragile delicate aircraft negotiated those massive obstacles by way of bludgeoning it's way tthrough.

Others said it and I will too. Your "intuition" and "common sense" are not serving you well, bill. For example, foam, similar to a styrafoam ice chest. punched a hole in the space shuttle wing:

www.pbs.org/wgbh/nova/columbia/impact.html

Even some experienced scientists and engineers thought this couldn't happen. It took a demonstration with a full scale mockup to show that it could and undoubtedly did. An insubstantial object, impacting at sufficiently high velocity, can damage or destroy a much more substantial object.

Regards,

ferd

 

[bill smith]

Others said it and I will too. Your "intuition" and "common sense" are not serving you well, bill. For example, foam, similar to a styrafoam ice chest. punched a hole in the space shuttle wing:

www.pbs.org/wgbh/nova/columbia/impact.html

Even some experienced scientists and engineers thought this couldn't happen. It took a demonstration with a full scale mockup to show that it could and undoubtedly did. An insubstantial object, impacting at sufficiently high velocity, can damage or destroy a much more substantial object.

Regards,

ferd

Let me think bout it ?........No-no way. End of story.

 

[Dave Rogers]

Let me think

I'm going to have to see some evidence of that.

Dave

 

[Gamolon]

Rigid body : An idealized extended solid whose size and shape are definitely fixed and remain unaltered when forces are applied. Treatment of the motion of a rigid body in terms of Newton's laws of motion leads to an understanding of certain important aspects of the translational and rotational motion of real bodies without the necessity of considering the complications involved when changes in size and shape occur. Many of the principles used to treat the motion of rigid bodies apply in good approximation to the motion of real elastic solids. See also Rigid-body dynamics.

I have a couple of questions for anyone who can answer them.

1. Am I correct in saying that a rigid body does not actually exist in the real world, but that the term rigid body is just a concept used for calculations? Hence the word "IDEALIZED" in the definition above?

2. I have done a little research on the term "rigid body" and have seen reference to car design, structural design, etc. Since Heiwa is arguing that the upper part of the tower can not be considered a "rigid body", I would like him to give me an example of a real world "rigid body". The definition Heiwa provides above says that "size and shape are definitely fixed and remain unaltered when forces are applied". As pointed out by others, doesn't this practically eliminate almost everything on the planet?

 

[Dave Rogers]

1. Am I correct in saying that a rigid body does not actually exist in the real world, but that the term rigid body is just a concept used for calculations? Hence the word "IDEALIZED" in the definition above?

Yes, and this is absolutely fundamental. Since any force applied to one end of a body cannot be transmitted to the other end at greater than the speed of light, the concept of a truly rigid body violates causality.

2. I have done a little research on the term "rigid body" and have seen reference to car design, structural design, etc. Since Heiwa is arguing that the upper part of the tower can not be considered a "rigid body", I would like him to give me an example of a real world "rigid body". The definition Heiwa provides above says that "size and shape are definitely fixed and remain unaltered when forces are applied". As pointed out by others, doesn't this practically eliminate almost everything on the planet?

Strike "almost". I'm not an engineer so I can't give an authoritative opinion, but since logically there is no such real object as a rigid body, and engineers define real-world objects as rigid bodies, then the term must relate to an approximation to rigid behaviour. The definition "size and shape are not significantly altered when forces are applied" would make sense, provided the level of significance was quantified.

Dave

 

[ferd burfle]

Let me think bout it ?........No-no way. End of story.

Based on your posts, I didn't expect you to be teachable, but I am curious about why you say "no way". Do you think they faked the demonstration? Or you reject this based on your superior knowledge of physics and engineering?

Thanks,

ferd

 

[Gamolon]

Yes, and this is absolutely fundamental. Since any force applied to one end of a body cannot be transmitted to the other end at greater than the speed of light, the concept of a truly rigid body violates causality.



Strike "almost". I'm not an engineer so I can't give an authoritative opinion, but since logically there is no such real object as a rigid body, and engineers define real-world objects as rigid bodies, then the term must relate to an approximation to rigid behaviour. The definition "size and shape are not significantly altered when forces are applied" would make sense, provided the level of significance was quantified.

Dave

Thanks Dave.



My next question. Since Heiwa is arguing that the upper part of the tower cannot be a "rigid body", can he or someone else please give me an example of what WOULD represent "rigid body" using the definition above?

Since I am on Heiwa's ignore list, can someone please ask him to provide an example of a "rigid body" that would fit the definition above?

 

[Newtons Bit]

Yes, and this is absolutely fundamental. Since any force applied to one end of a body cannot be transmitted to the other end at greater than the speed of light, the concept of a truly rigid body violates causality.



Strike "almost". I'm not an engineer so I can't give an authoritative opinion, but since logically there is no such real object as a rigid body, and engineers define real-world objects as rigid bodies, then the term must relate to an approximation to rigid behaviour. The definition "size and shape are not significantly altered when forces are applied" would make sense, provided the level of significance was quantified.

Dave

A common solution to analyzing lateral forces on buildings is to assume that the floor diaphragm is rigid. This makes analyzing where the lateral forces from an earthquake (which is a function of the mass on the diaphragm) go much simpler. All you need to know is the relative stiffness of each of the lateral force resisting elements and their respective distances to the center of the diaphragm.

It's allowed by code as it's "close enough", but with FEA where it is now, we engineers have begun to use diaphragms with accurate stiffnesses. It makes a fairly large difference in the forces on lateral force resisting elements.

 

[Gamolon]

Bazant's definition seems eminently clear to me: A "rigid body" is a structure that moves thru space as a unit UNTIL some component's stress exceed its ultimate strength. At which point, that component detaches from the parent rigid body."

Is this the true definition of the term "rigid body" when used in a structural sense? It makes perfect sense to me.

I still would like Heiwa to provide me an example of a rigid body that fits his definition he posted.

 

[tsig]

Thanks Dave.



My next question. Since Heiwa is arguing that the upper part of the tower cannot be a "rigid body", can he or someone else please give me an example of what WOULD represent "rigid body" using the definition above?

Since I am on Heiwa's ignore list, can someone please ask him to provide an example of a "rigid body" that would fit the definition above?

"In physics, a rigid body is an idealization of a solid body of finite size in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it. Even though such an object cannot physically exist due to relativity, objects can normally be assumed to be perfectly rigid if they are not moving near the speed of light."


http://en.wikipedia.org/wiki/Rigid_bodies

 

[bill smith]

Based on your posts, I didn't expect you to be teachable, but I am curious about why you say "no way". Do you think they faked the demonstration? Or you reject this based on your superior knowledge of physics and engineering?

Thanks,

ferd

Do you mean the F4 ? If so I do not compare chalk with cheese. You may do so at your leisure.

Let me show you a little picture. Maybe you will get a clue.

http://nomoregames.net/presentations/Madison_No_Planes_Final_August_07.ppt_files/slide0045_image034

 

[Gamolon]

"In physics, a rigid body is an idealization of a solid body of finite size in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it. Even though such an object cannot physically exist due to relativity, objects can normally be assumed to be perfectly rigid if they are not moving near the speed of light."


http://en.wikipedia.org/wiki/Rigid_bodies

I saw that too.

Again, if Heiwa is rejecting the concept of the upper part of the tower being a rigid body, what then, by his definition, would be a good example OF a rigid body?

Would a solid block of concrete with the same dimensions as the upper part of the tower suffice as a rigid body?

Please Heiwa. What would you give as an example of a rigid body?

 

[bill smith]

Is this the true definition of the term "rigid body" when used in a structural sense? It makes perfect sense to me.

I still would like Heiwa to provide me an example of a rigid body that fits his definition he posted.

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

 

[Gamolon]

My point in all this rigid body talk is that Heiwa is applying a conceptual idea (which, by it's own definition, cannot physically exist anywhere) to a real world object.

By saying that the upper portion of the tower does not fit a the definition of a rigid body, he is indirectly saying that there is a structure or object that fits the definition.

What is that structure or object?

 

[Gamolon]

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

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

 

[FineWine]

I dubbed Ryan Mackey 'The Flying Debunker' some time ago. It's a pretty accurate description. He flies in, lays a strategic egg and flies out again. He does not wait around to debate. In one way I understand this as he has a lot to lose by taking the risk.

Incidentally the'ignore' feature provides himself and peoole like you an opportunity to say that he has not seen a particular post and that that's why he does not engage. Not everybody is entirely persuaded by this though.

Do you ever ask yourself why Mackey might not be interested in "debating" with you? You displayed your ignorance of basic physics by mocking the notion that water can cut steel. As water can cut steel, you succeeded only in making a fool of yourself. You were directed to Mackey's lecture, in which he explained the physics of the plane crashes. You claimed that you started to watch, but now it turns out that you weren't capable of learning a thing. Please tell us what a NASA engineer stands to lose by trying to explain the science he uses on his job to someone who simply can't learn.

 

[bill smith]

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

Not really. Not in the empircal sense. I assume Bazant theorised a block that stayed undamaged to the end and was hhen conveniently crushed up. What are we arguing Bazant for anyway ? Bazant is done and dusted and out of the picture.