A Truther writes...

[W.D.Clinger]

Oh well, here goes with the response to Oystein's response

He's just confirming T.A.M.'s diagnosis. His talk of "blowing smoke" and "Is this guy supposed to be a scientist?" must be psychological projection^WP. He's heard of conservation of momentum, and is using that phrase to project a false air of authority, but he doesn't know how to use conservation of momentum to calculate the effects of an inelastic collision:

Which might have achieved some equilibrium what with losing all that structure mass to powder, flying girders an' all, but your mate ignores the point entirely, and is blowing smoke yet again. There is absolutely no way the falling structure would make the floors below assume the VELOCITY (and not just the momentum) and continue the progression.
*

Nice try, maybe worth 2.5/10 and it might even pass as plausible to someone completely ignorant about physics, but please get better help than this if you seriously want to refute my argument on momentum.

His argument is refuted by a simple calculation based on the law of conservation of momentum. That's first-semester freshman physics.

glenn: “…how does each new floor suddenly assume the accumulated velocity of the falling floors above?”

Angry: ----Strawman.

His question wasn't a strawman so much as idiocy. In particular, his question revealed profound ignorance of freshman physics.

Conservation of momentum tells us that the total momentum of the upper block plus the new floor is the same after their collision as before. The collision was (approximately) inelastic, which means the upper block and the new floor had the same velocity after the collision. Using the mass and velocities of the upper block and the new floor before the collision, you can use the law of conservation of momentum to calculate their velocity after the collision. Because the mass of the new floor was small compared to the mass of the upper block, the velocity of the combined upper block and new floor had to be almost as large as the velocity of the upper block just before the collision. That's physics.

This "glenn" person is just repeating "conservation of momentum" while denying the most basic consequences of that physical law.

It doesn not assume the speed, it assumes the momentum, thereby losing some speed (as some of the mass starts out at rest)----

Strawman my arse. If it did _not_ assume the speed, how does your mate account for the fact that we saw acceleration at virtually free-fall speed, which was the actual point? Slippery customer, this mate of yours.

Your statement there was incorrect. The new floor assumes a small fraction of the momentum of the upper block, thereby assuming most of its speed. That too is physics.

ETA: As I wrote earlier in the thread, and as Oystein has elaborated:

Competent video analysis shows diminutions of velocity considerably in excess of what is predicted by conservation of momentum. In other words, the effect predicted by conservation of momentum was small relative to the reduction in velocity caused by the supporting strength that remained within the compromised structure below.

This glenn person claims the observed loss of velocity was smaller than predicted by the law of conservation of momentum. That's factually incorrect: the loss of velocity was greater.

 

[Oystein]

...
His argument is refuted by a simple calculation based on the law of conservation of momentum. That's first-semester freshman physics.

In Germany, that is 11th grade high school physics

...
...
Your statement there was incorrect. The new floor assumes a small fraction of the momentum of the upper block, thereby assuming most of its speed. That too is physics.

Yes, most of the speed. Not all of it.

Let's denote the top 15 stories with sub-t, and the new 1 story with sub-n, and the two combined as sub-t+n.
Momentum is p, velocity is v, mass is m

Then just before inelastic collision:
m_t = 15m_n
v_t has a certain value
v_n = 0
p_t = 15m_nv_t
p_n = 0*m_n = 0

Just after inelastic collision:
m_t+n = m_t + m_n = 16m_n
p_t+n = p_t + p_n = p_t (that is the equation for conversation of momentum!)
v_t+n = p_t+n / m_t+n = p_t / 16m_n = 15m_nv_t / 16m_n = 15/16 * v_t
v_n(after collision) = v_t+n because that is the definition of an inelastic collision; = 15/16 * v_t

So the new floor does not pick up the full velocity of the falling block but 15/16th of it. In other words, the top 15 storys only loose 1/16th or 6.25% of their velocity because of the collision.

They lose some more to planet earth by pushing the columns all the way down into the ground; how much is now a somewhat complicated matter that invoves elasticity, conversation of energy, and the many ways that kinetic energy gets converted into heat, deformation, fractures, potential energy (springs) and seismic waves. That's where real scientific papers like the one by Bazant come into play.

 

[excaza]

Your statement there was incorrect. The new floor assumes a small fraction of the momentum of the upper block, thereby assuming most of its speed. That too is physics.

The body resulting from the inelastic collision of two or more bodies will assume all the momentum of the bodies. Not just some of it.

From your other postings I'm assuming you know that, but your above statement is incorrect. Unless your use of "assumes" is regarding the energy dissipated by the floor breaking its supports.

 

[The Big Dog]

I'm not quite sure what he is talking about but I do have a few pictures here of clean-up crews working on the site which I would like to add to:

http://angrysoba.blogspot.com/2009_07_01_archive.html

Do you know where I could find similar pictures which show the beams being cut?

---I should also have edited that part out of my mate's post because I don't want the focus to be on such easily distracting questions---

The picture he is talking about is the second from the bottom on your page. Except it is truther cropped to show only the firman in the middle and the angle cut beam, not the other beams, nor the demolition worker in the background.

I don't know why you'd edit that out, he thinks he can score some cheap points lying about "thermite" and some laughs at the expense of the FDNY? **** him, he gets what he deserves.

 

[angrysoba]

The picture he is talking about is the second from the bottom on your page. Except it is truther cropped to show only the firman in the middle and the angle cut beam, not the other beams, nor the demolition worker in the background.

I don't know why you'd edit that out, he thinks he can score some cheap points lying about "thermite" and some laughs at the expense of the FDNY? **** him, he gets what he deserves.

I'd edit it out because his "point" distracts from the main discussion which is that of conservation of momentum.

 

[angrysoba]

Thanks for the feedback, W.D Clinger!

 

[carlitos]

Angry:----Drop a paper bag full with assorted things (screws, tomatoes, marbles, toys) from your upper floor down onto your terrace. Watch what happens. See how some of the things are flung sideways?----

Your mate is an idiot. If I dropped a sack full of _heavy_ bolts which are not going to be blown around by the wind, they'll land pretty much
below where they are dropped. What made the 40-ton steel girders of the Twin Towers go laterally with such substantial energy - brownian motion, perhaps?

Not that it will help, perhaps you should have said to drop from your upper floor to your terrace, with the bag hitting several tree branches and a patio along the way. The girders being tossed about were not at ground level, so they had a long way to fall (gravity) with whatever sideways force they carried from the collision.

All that aside, I have seen this glenn name before, and I don't think that your dialogue will be productive. I suggest learning a new language or planning a vacation as better uses of your time.

 

[W.D.Clinger]

The body resulting from the inelastic collision of two or more bodies will assume all the momentum of the bodies. Not just some of it.

Yes, that's true of the combined body. If you reread my statement, I think you'll realize I was talking about the fraction of that combined body that corresponds to the previously stationary floor. Your clarification is useful, however, and I thank you for it.

 

[bill smith]

I'm not quite sure what he is talking about but I do have a few pictures here of clean-up crews working on the site which I would like to add to:

http://angrysoba.blogspot.com/2009_07_01_archive.html

Do you know where I could find similar pictures which show the beams being cut?

---I should also have edited that part out of my mate's post because I don't want the focus to be on such easily distracting questions---

You should ask your friend whether he thinks the perps would really leave a cut beam like that and whether he doesn't get the taste of red herring ?

 

[angrysoba]

You should ask your friend whether he thinks the perps would really leave a cut beam like that and whether he doesn't taste a red herring ?

Well, they left all that nanothermite lying around and forgot to put the names of the patsies on the flight manifest so anything's possible, right?

 

[bill smith]

Well, they left all that nanothermite lying around and forgot to put the names of the patsies on the flight manifest so anything's possible, right?

Well in this case it couldn't be more obvious. You didn't think that the conspiracy theories got started all on their own did you ?

 

[Bell]

Well in this case it couldn't be more obvious. You didn't think that the conspiracy theories got started all on their own did you ?

No, by crazies like you

 

[triforcharity]

'm sure that's all very very interesting and the Readers can read it if they want. But I am appealing to people's personal experience and intuition here. To what they know in their bones. And I believe that they know in their bones that one tenth of an object will never crush nine tenths of the same structure down flat on the ground by gravity alone as we saw on 9/11.

You can maybe convince a few Readers by here and now describing a documented event in the entire recorded history of this planet where one-tenth of any object, large or small has crushed the other nine-tenths of the same structure by gravity alone. For instance the collapse of the spagetti model will arrest almost immediately. It's intuitive you see ?

And what if their personal experience is plumbing? Would you trust their judgement on structural engineering? What if they are the pooper-scooper at the circus? Are they also qualified to judge structrual engineering?

No. Of course not Bill. Not one iota. You are appealing to their personal beliefs, not facts.

Now, stop comparing the WTC to a bunch of spagetti.

 

[triforcharity]

Then make with the countless other documented examples there must be if this can really happen. I am willing to accept examples from the entire recorded history of planet Earth of any pther of millions of different types of structure where the top one tenth has crushed the other nine-tenths of the same object by gravity alone.

Let's face it....if you cannot do this simple thing then we have no reason to believe that it can happen at all except in a managed way like the deliberate demolitions on 9/11.

http://www.nbcnewyork.com/news/loca...d-in-NJ-Parking-Garage-Collapse-98661744.html

Now, STFU. Gravity alone there sparkplug.

 

[bill smith]

http://www.nbcnewyork.com/news/loca...d-in-NJ-Parking-Garage-Collapse-98661744.html

Now, STFU. Gravity alone there sparkplug.

How tall a steel framed hi-rise was that. It's hard to tell from the video

 

[Horatius]

Then make with the countless other documented examples there must be if this can really happen. I am willing to accept examples from the entire recorded history of planet Earth of any pther of millions of different types of structure where the top one tenth has crushed the other nine-tenths of the same object by gravity alone.

Let's face it....if you cannot do this simple thing then we have no reason to believe that it can happen at all except in a managed way like the deliberate demolitions on 9/11.

http://www.nbcnewyork.com/news/loca...d-in-NJ-Parking-Garage-Collapse-98661744.html

Now, STFU. Gravity alone there sparkplug.

How tall a steel framed hi-rise was that. It's hard to tell from the video

Watch those goalposts fly!

 

[bill smith]

Watch those goalposts fly!

How tall to you think it was from the video Horatius ?

 

[Dog Town]

You didn't think that the conspiracy theories got started all on their own did you ?

Does your "argument", even read the words you type?

 

[triforcharity]

How tall a steel framed hi-rise was that. It's hard to tell from the video

3 Stories tall IIRC, and it was a concrete structure. But, of course, now you change your requirements. Now it has to be a steel framed structure. But originally, you did not set that requirement.

Here is your post EXACTLY.

Then make with the countless other documented examples there must be if this can really happen. I am willing to accept examples from the entire recorded history of planet Earth of any pther of millions of different types of structure where the top one tenth has crushed the other nine-tenths of the same object by gravity alone.

Let's face it....if you cannot do this simple thing then we have no reason to believe that it can happen at all except in a managed way like the deliberate demolitions on 9/11.

Iv'e hilited and made the relevant parts more noticeable. You even specifically state DIFFERENT TYPES of structures.

Now, I wanna know, honestly, how did you get those goalposts to move so quick?

You must have one of these nifty little inventions.

 

[bill smith]

3 Stories tall IIRC, and it was a concrete structure. But, of course, now you change your requirements. Now it has to be a steel framed structure. But originally, you did not set that requirement.

Here is your post EXACTLY.



Iv'e hilited and made the relevant parts more noticeable. You even specifically state DIFFERENT TYPES of structures.

Now, I wanna know, honestly, how did you get those goalposts to move so quick?

You must have one of these nifty little inventions.
[qimg]http://i80.photobucket.com/albums/j182/swiftian/zaius2008l/golaposts2.jpg[/qimg]

Do you have any more amusing examples tri ? You can choose examples from the last 4,500 million years