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Just a small realization....

Mercutio

Penultimate Amazing
Joined
Mar 31, 2003
Messages
16,279
A couple of threads over the past few days made me finally realize something. Maybe this is old news to most (or all) of you, but it hit home for me.

Anyway, one of the inspirations for this is Morgan Reynolds's "request for correction", arguing that the impact of the planes, and the subsequent movement of the towers, proves that the planes could not have been real. In a nutshell, the argument is that the towers bend more in a strong wind than they did being hit by loaded jetliners. The forces, the argument goes, could not be that terribly strong if they did not cause even as much bend as the wind does. In fact, one post on another thread calculated the force that should have been carried by fully loaded jetliners and calculates (if memory serves) the amount of bend that we should have seen--the amount we did see is considerably less.

Sounds pretty damning. I had never heard this particular argument before this week, and I don't know that I would have found it particularly convincing or not...but something in these couple of threads triggered a memory. I don't know much about the towers (compared to the folks here), but this thing I do know about.

I have a bed of nails in my office. I use it for "mind over matter" demos, and to show that the physics behind it, rather than any bioenergetic force field, is what keeps me safe. One of the things I do is lay a concrete block on my stomach and have someone hit it with a sledge hammer. This is the part that is important to this thread. Twice, people have been a bit hesitant, and have hit the block with insufficient force to break it. This has the effect of pushing my back against a couple hundred nails, and is not terribly comfortable. Most times, though, people are pretty enthusiastic about swinging a sledgehammer at me, and the concrete block shatters in two, in a cloud of dust and concrete chips. When this happens, I don't feel any pressure at all. The energy is put into breaking the concrete block apart, and cannot be used to push me into the nails.

Exactly the same thing, I think, was at work at the Twin Towers. Of course the buildings did not sway as much as the calculations predict; that energy was being used tearing columns, walls, floors, elevator shafts, apart. Reynolds claims it proves there were no planes; rather, it proves that this energy was spent in destroying the building. The same energy that, if distributed as wind is, would have bent the towers significantly, was distributed in the much smaller "footprint" of the plane, causing more localized and much more significant damage. Like a high-speed bullet disintegrating and spending all its energy in a body, the plane spent all its energy in tearing apart a couple of floors. Reynolds has convinced me of precisely what he claims is not the case.

Sorry if everybody here but me already knew this. I knew that at least one (Reynolds) did not.
 
It is a brilliant point, that actually hurts their arguement. The less movement of the towers seen, the more energy went into destruction of the inerts of the towers, hence all the more contribution from the airliner crashes to the eventual collapse of the buildings.

Nice point I had not heard before.

TAM:)
 
That is a very good point. There is a second simple debunking, and that is pressure. Yes, the wind might apply a larger overall force to the side of the tower, but that force is distributed over an entire face. As such, there is comparatively little stress on individual structural elements. When each plane hit, on the other hand, the force was distributed over a very small area. So even though the overall force was smaller, the pressure was much higher. The individual elements in each plane's path saw much higher stress as a result. This higher stress caused failure.

You demonstrate this point as well when you use your bed of nails. By laying on so many nails, you decrease the force that is carried by each one enough so that they do not hurt you. If you tried to lay on just one, it would be a very bad day.

The relationship between force, pressure, and area is linear, so simple ratios can be used to determine which would be more damaging. If the impact area of the plane was 1/110th of the area on one face of the tower, for example, then the overall force supplied by the plane would have to be 1/110th of the force supplied by the wind for the pressures to be equal. The area of the plane impacts were much smaller than the area of a tower face, so it would be difficult to make a good judgment simply based on the bending of the towers (especially since bending is not linear).
 
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Your blocks remind me of my martial arts demonstrations. Breaking boards hurts no matter what you do, but if you don't break the board, it hurts horribly. The end result is that a broken board requires only the energy necessary to break the board to be transmitted back to your hand (ala Newton's 3rd). If you don't break it, all of the force you have goes into pushing the people holding the board back a few steps.
 
Yeah, but Mercutio, you're still assuming that the planes that hit the towers were real and that the destruction of the towers was not accomplished by controlled demolition! See how easily I blew away your house of cards?

PS- The above is sarcasm. Overused and trite? Probably, but I use what I've got, and it ain't much. :D
 
Yeah, but Mercutio, you're still assuming that the planes that hit the towers were real and that the destruction of the towers was not accomplished by controlled demolition! See how easily I blew away your house of cards?

PS- The above is sarcasm. Overused and trite? Probably, but I use what I've got, and it ain't much. :D

:D

(For those who don't get it--you are right; that is indeed what I am assuming. But the upshot is, Reynolds claims that this observation is incompatible with a real plane; I am saying it is quite compatible, and that it shows that the missing energy is every bit as easily explained as having been spent destroying the structure.)
 
What a sad, sad man. (Reynolds, that is. Mercutio is carefree and gay). It would be great if NIST would send Reynolds a DVD on which they've recorded their staff giving him the international cuckoo sign.

I'd love to be his lawyer, though. "Hey, Morgan, those pants just called you a name. Let's sue the Gap."
 
A couple of threads over the past few days made me finally realize something. Maybe this is old news to most (or all) of you, but it hit home for me.

Anyway, one of the inspirations for this is Morgan Reynolds's "request for correction", ...

Sounds pretty damning. I had never heard this particular argument before this week, and I don't know that I would have found it particularly convincing or not...but something in these couple of threads triggered a memory. I don't know much about the towers (compared to the folks here), but this thing I do know about.

Exactly the same thing, I think, was at work at the Twin Towers. Of course the buildings did not sway as much as the calculations predict; that energy was being used tearing columns, walls, floors, elevator shafts, apart. Reynolds claims it proves there were no planes; rather, it proves that this energy was spent in destroying the building. The same energy that, if distributed as wind is, would have bent the towers significantly, was distributed in the much smaller "footprint" of the plane, causing more localized and much more significant damage. Like a high-speed bullet disintegrating and spending all its energy in a body, the plane spent all its energy in tearing apart a couple of floors. Reynolds has convinced me of precisely what he claims is not the case.
It sounds good and explains how the energy of the plane was concentrated on a small cross section. The planes impacts were equal in energy to 1300 to 2200 pounds of TNT at those speeds and the engines were going full blast. I like your explanation. I wish I could write as well, and go get a PhD in engineering.

So where are you going to teach physics this year?
 
Of course another excellent Debunking of this theory is the fact hundreds of survivors from the towers report that they swayed enormously for almost a minute after impact.

Some survivors report getting motion sickness, and in some instances objects fell off shelves and wheeled chairs rolled about.

-Gumboot
 
I don't have a link to one right now, but most of you will have seen one of these high-speed photos of a rifle bullet going through an apple (or some other fruit). I now ask you to make an experiment (at least in your head):

Mount an apple in a similar way (it is usally stuck on a spent cartridge).

Now, take a pencil and slowly push it straigh through the apple.

Can you (or do you think you can) do that without pushing the apple off the holder?

Right, you can't. However, the rifle bullet can go right trough and even make parts of the apple disperse explosively from both ends of the hole.

Why is this? It is exactly due to the speed of the bullet. To accelerate an object, be it an apple or a skyscraper, you need to apply energy to it. Not just force, but energy. The faster you need to accelerate it, the more energy do you need to apply. This energy needs then to be transferred to the rest of the object. During the impact of a fast projectile, there is very little time to transfer energy. Since energy is force multiplied by time, it follows that the force must be high. If the force is high enough, it will exceed the structural strenght of the stationary object. Thus, instead of being pushed, it will be penetrated.

This is the reason a bullet can penetrate an apple without pushing it off a not very solid mounting and an airliner can penetrate a building without displacing it as much as wind could do. The similarity stops here. In the case of the airliner impact, the force excerted in the short timespan of the penetration also exceeds the structural strenght of the airliner, so both the impacted part of the building AND the airliner will disintegrate before there is time to transfer much of the energy to the rest of the building. Instead, the released energy turns into heat around the impact point.

Hans
 
But are there 'fizzies?'

Ah...I...see...

No iron in the current demonstration (other than the sledge). I suppose I will have to try it again, this time using 3" rebar on 4' centers.

@Beachnut--I am flattered, but I do not teach physics, but psychology. Physics was much too easy. I do remember, though, reading my mom's physics books (she taught it) back in grade school; it is good to know I have not forgotten all of it.

@Chillzero--Given this demonstration, I would much rather have them swing the hammer with some gusto than try to be nice. The best was a guy I used to share an office with. Lots of pent-up rage there, I suppose...
 
@Chillzero--Given this demonstration, I would much rather have them swing the hammer with some gusto than try to be nice. The best was a guy I used to share an office with. Lots of pent-up rage there, I suppose...

... as long as they are only taking great pleasure in swinging sledghammers at you when you are engaged in this particular demonstration ... and not.... like, you know.... when you are waiting for a lift (elevator) or something. :D
 
I don't have a link to one right now, but most of you will have seen one of these high-speed photos of a rifle bullet going through an apple (or some other fruit). I now ask you to make an experiment (at least in your head):

Mount an apple in a similar way (it is usally stuck on a spent cartridge).

Now, take a pencil and slowly push it straigh through the apple.

Can you (or do you think you can) do that without pushing the apple off the holder?

Right, you can't. However, the rifle bullet can go right trough and even make parts of the apple disperse explosively from both ends of the hole.

Why is this? It is exactly due to the speed of the bullet. To accelerate an object, be it an apple or a skyscraper, you need to apply energy to it. Not just force, but energy. The faster you need to accelerate it, the more energy do you need to apply. This energy needs then to be transferred to the rest of the object. During the impact of a fast projectile, there is very little time to transfer energy. Since energy is force multiplied by time, it follows that the force must be high. If the force is high enough, it will exceed the structural strenght of the stationary object. Thus, instead of being pushed, it will be penetrated.

This is the reason a bullet can penetrate an apple without pushing it off a not very solid mounting and an airliner can penetrate a building without displacing it as much as wind could do. The similarity stops here. In the case of the airliner impact, the force excerted in the short timespan of the penetration also exceeds the structural strenght of the airliner, so both the impacted part of the building AND the airliner will disintegrate before there is time to transfer much of the energy to the rest of the building. Instead, the released energy turns into heat around the impact point.

Hans


I've worked on the 54th floor in Manhattan (One Penn Plaza), and on windy days, the building sometimes swayed so much that the computer mouse began to glide.

A very weird experience.

But the building didn't move on other, far more windy days. The "trick" is that, not only does the wind have to push the building for a while to set it in motion, it also has to hit it at a specific angle.

What most people don't think about is that there is a hell of a lot of energy in moving air at high speeds.
 
I've worked on the 54th floor in Manhattan (One Penn Plaza), and on windy days, the building sometimes swayed so much that the computer mouse began to glide.

A very weird experience.

But the building didn't move on other, far more windy days. The "trick" is that, not only does the wind have to push the building for a while to set it in motion, it also has to hit it at a specific angle.

What most people don't think about is that there is a hell of a lot of energy in moving air at high speeds.
I experienced this in the Gateway Arch in St. Louis. Very weird, and having a fear of heights doesn't help!
 
Harold Edgerton's "apple" can be found here at

web.mit.edu/museum/exhibitions/edgerton.html

as well as information about his life.
The strides that Edgerton made in night aerial photography during World War II were instrumental to the success of the Normandy invasion and, for his contribution to the war effort, Doc was awarded the Medal of Freedom. During the Cold War, Edgerton and his partners at EG&G (Edgerton, Germeshausen, and Grier) made it possible to document nuclear explosions, an advance of incalculable scientific significance. In the last three decades of his life, Edgerton concentrated on sonar and underwater photography, illuminating the depths of the ocean for undersea explorers such as Jacques Cousteau, who dubbed his good friend “Papa Flash.”​
 

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