# The Naked Scientists Forum

### Author Topic: Conservation of Momentum in a Gravitational Collapse  (Read 45119 times)

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #50 on: 10/05/2009 14:34:57 »
The examples you've calculated are the wrong ones.

You need to calculate the case with 1,2,4,8 or other exponentially increasing masses. That's what the mass in the WTC did- all really tall buildings have (more or less)an exponentially increase in the mass as you go down the building. The counterintuitive result with exponentially increasing masses is that if the collapse starts, it (nearly always) carries on.

(The reason it's exponential is that if you make it exponential, then it's possible to make the building almost infinitely tall in principle- in practice it eventually gets spindly enough that it gets unusably thin, so they stop.)
« Last Edit: 10/05/2009 14:42:41 by wolfekeeper »

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #51 on: 16/05/2009 20:51:11 »
The examples you've calculated are the wrong ones.

You need to calculate the case with 1,2,4,8 or other exponentially increasing masses. That's what the mass in the WTC did-

Oh really?  And what do you think that would accomplish?

What do you think the point of my calculations was?

The linear sequence with the heaviest mass at the top took 19% longer than free fall.  The constant sequence took 28% longer than free fall.  The linear sequence with the heaviest mass at the bottom took 43% longer than free fall.

So the sequence you are suggesting would have to take even longer.  It is commonly said that the north tower came down in 11 seconds which is only 20% longer than the free fall time.  My objective was to demonstrate that conservation of momentum alone would slow a top down collapse caused by the plane such that everyone should recognize that it could not have occurred.

So you are helping me win the war by claiming to have beaten me at a skirmish.  Your assistance is most welcomed.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #52 on: 16/05/2009 21:17:19 »
Uh huh. So you presumably did the calculation and it didn't work.

It's all nonsense anyway; the building did fall down in the time that is showed on the video.

I don't care what calculation you can show that says otherwise; it fell down in that particular time. If your calculation says otherwise, your calculation is wrong.

The other thing you're failing to consider is that the structural failure happened at the speed of sound in steel. That's 4.5 km/s, so the entire metal structure can fail in the time that it takes the shock wave to travel the length of the building; very short. Basically the whole top few floors of the building acts as a pile drive and after falling onto the bottom section, the whole structure will fail in about a tenth of a second, then it's just gravity acting; everything just falls together.
« Last Edit: 16/05/2009 21:29:51 by wolfekeeper »

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #53 on: 17/05/2009 00:16:58 »
Uh huh. So you presumably did the calculation and it didn't work.

It's all nonsense anyway; the building did fall down in the time that is showed on the video.

I don't care what calculation you can show that says otherwise; it fell down in that particular time. If your calculation says otherwise, your calculation is wrong.

You can presume whatever you like.  I didn't bother doing the calculations.  The larger the stationary mass the more it slows down the mass falling on it.

I am not disputing the collapse time.  I am just pointing out the IMPOSSIBILITY of it being a top down collapse without something destroying the supports to make it happen in that time frame.

psik

#### L_D

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #54 on: 17/05/2009 07:19:17 »
It's all nonsense anyway; the building did fall down in the time that is showed on the video.

I don't care what calculation you can show that says otherwise; it fell down in that particular time. If your calculation says otherwise, your calculation is wrong.

The other thing you're failing to consider is that the structural failure happened at the speed of sound in steel. That's 4.5 km/s, so the entire metal structure can fail in the time that it takes the shock wave to travel the length of the building; very short. Basically the whole top few floors of the building acts as a pile drive and after falling onto the bottom section, the whole structure will fail in about a tenth of a second, then it's just gravity acting; everything just falls together.

The upper portions of these buildings are approx 1/5 the mass of the lower portions, if anything is going to be smashed on impact it will be the weak upper portion, not the stronger undamaged lower portions. Also even if a shock wave were to somehow have destroyed the lower portion on impact then the collapse should represent that, rather than the progressive type of collapses we see.

With regard to earlier discussion of the mass of the building increasing lower down, I'm pretty sure it is only the steel columns that get bigger and thicker, the concrete and steel girders for the floors are uniform throughout the whole building.

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #55 on: 18/05/2009 01:24:41 »
It's all nonsense anyway; the building did fall down in the time that is showed on the video.

I don't care what calculation you can show that says otherwise; it fell down in that particular time. If your calculation says otherwise, your calculation is wrong.

The other thing you're failing to consider is that the structural failure happened at the speed of sound in steel. That's 4.5 km/s, so the entire metal structure can fail in the time that it takes the shock wave to travel the length of the building; very short. Basically the whole top few floors of the building acts as a pile drive and after falling onto the bottom section, the whole structure will fail in about a tenth of a second, then it's just gravity acting; everything just falls together.

The upper portions of these buildings are approx 1/5 the mass of the lower portions, if anything is going to be smashed on impact it will be the weak upper portion, not the stronger undamaged lower portions.
Nope, you've still missed the point.

If, for example the mass of the building goes 1,2,4,8,16

and 1,2 falls onto 4, and 4 is designed to withstand 50% at dynamic overload, let's assume that floor 1 and 2 acts as if it was twice as heavy when it impacts (due to momentum), then 4 will immediately fail and then 1,2,4 will fall onto 8, which will immediately fail and so on; the percentage overload *increases* as the failure propagates  1+2+4/8 is 7/8 whereas 1+2/4 is only 3/4.
Quote
With regard to earlier discussion of the mass of the building increasing lower down, I'm pretty sure it is only the steel columns that get bigger and thicker, the concrete and steel girders for the floors are uniform throughout the whole building.
Probably, but it doesn't matter; the total mass still goes up exponentially along the length of the building.
« Last Edit: 18/05/2009 01:27:38 by wolfekeeper »

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #56 on: 18/05/2009 02:53:31 »
If, for example the mass of the building goes 1,2,4,8,16

and 1,2 falls onto 4, and 4 is designed to withstand 50% at dynamic overload, let's assume that floor 1 and 2 acts as if it was twice as heavy when it impacts (due to momentum), then 4 will immediately fail and then 1,2,4 will fall onto 8, which will immediately fail and so on; the percentage overload *increases* as the failure propagates  1+2+4/8 is 7/8 whereas 1+2/4 is only 3/4.
Probably, but it doesn't matter; the total mass still goes up exponentially along the length of the building.

Then you missed the point of my gravitational collapse calculations.

DYNAMIC OVERLOAD has nothing whatsoever to do with those collapse times.  I said the masses were held up by MAGIC and moved the instant they were hit from above.  There were no supports to overload.  So the distribution of mass that you propose would just fall even more slowly than mine because you increase mass more than I do.

The conservation of momentum and the energy required to break the supports are two separate factors.  That is why I did drops on toothpicks without washers to show the breakage effect without mass.  It is difficult to support masses by magic in real life.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #57 on: 19/05/2009 19:14:00 »
You haven't even attempted to scale things appropriately.

I'm sorry but your simulation is simply nonsense, it is so very far removed from the real mass distribution, strength and speeds of the WTC that you can draw no conclusions at all.

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #58 on: 20/05/2009 00:23:49 »
You haven't even attempted to scale things appropriately.

I'm sorry but your simulation is simply nonsense, it is so very far removed from the real mass distribution, strength and speeds of the WTC that you can draw no conclusions at all.

If you watch both of my videos

You will notice that I have frames that ask about the tons of steel and tons of concrete on every level of the towers.

I did not try to build scaled models.  How can you build scaled models demonstrating the physics if you don't have the distribution of mass data on the subject?  The purpose of my designs was to demonstrate that the material that we do not have accurate information on had to affect what happened.

It doesn't even make sense to have an investigation without information that simple.  The NCSTAR1 report doesn't even specify the total quantity of concrete in the towers.

So you are correct in that it is not scaled.  I never claimed it was.  But the models are built to be variable and my collapse demonstrated that stationary masses slow the falling mass down.  But the strength of toothpicks in my collapse demonstration is constant while a real skyscraper must get stronger and heavier all of the way down.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #59 on: 20/05/2009 01:00:54 »
How can you build scaled models demonstrating the physics if you don't have the distribution of mass data on the subject?
Yes that would be impossible to determine, and there are no resources that you can draw on.

#### psikeyhackr

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« Reply #60 on: 20/05/2009 12:29:26 »
How can you build scaled models demonstrating the physics if you don't have the distribution of mass data on the subject?
Yes that would be impossible to determine, and there are no resources that you can draw on.

Sarcasm is so easy.  Let us see you Google the quantity and weights of the exterior wall panels.

I told you what to look for, so you didn't have to figure that out for yourself.

BELIEVERS don't need relevant information.  Understanding is more stringent.  Believers don't even need to figure out what questions to ask.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #61 on: 20/05/2009 13:27:53 »
This is a science board. And now for the science bit.

In science we develop a 'normal hypothesis' and try to disprove it. The normal hypothesis is the simplest possible theory about how something happened. We get the normal hypothesis by using Ockham's razor.

So, building gets hit by enormous aircraft full of flammable fuel, there is a huge fire started and then after an hour or so, the building fell down.

What is the normal hypothesis?

The normal hypothesis is that the fire causes the building to fall down.

Unless you can provide a reasonable model and use the available evidence to show that the normal hypothesis is wrong (to within statistical bounds), then the scientific position is that it fell down due to the fire.

You have not done the work necessary to disprove the normal hypothesis.

#### psikeyhackr

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« Reply #62 on: 20/05/2009 16:05:26 »
building gets hit by enormous aircraft full of flammable fuel, there is a huge fire started and then after an hour or so, the building fell down.

I love that SCIENTIFIC description.

The ENORMOUS aircraft was ONE HALF of ONE TENTH of ONE PERCENT the mass of the building.

There were 10,000 gallons of fuel onboard at the time of impact but the plane was capable of holding 25,000 gallons so it was nowhere near FULL of fuel.

A lot of people talk all this trash about being scientific but then they use lots of subjective and relative wording to support their position and then have the nerve to use the H-word like that can magically wrap them in the mantle of SCIENCE.  That ain't science that is PROPAGANDA!

If we don't have correct data about the objects in question then talking about a hypothesis is idiotic presumption.

What is the number and weights of the 12 types of exterior wall panels?  That is what the airliners hit first.

If you want to see a HUGE fire look at that hotel in Beijing THAT DID NOT COLLAPSE.

http://news.bbc.co.uk/2/hi/asia-pacific/7880348.stm

What does that say about your HUGE FIRE hypothesis?  There is of course the minor detail of the atmosphere only being 20% oxygen so that jet fuel doesn't burn as hot as in an engine that mixes the fuel and air properly.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #63 on: 20/05/2009 18:24:42 »
I note your excessive use of capital letters, and the fact that you still haven't got any relevant data; another hotel caught fire you say, that wasn't hit by an aircraft with 10,000 gallons of fuel, and didn't burn down? What does that prove?

I also note you seem to be surprised that fuel which has a equivalent energy of 450 tonnes of TNT could take down a structure like the world trade centre.

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #64 on: 20/05/2009 23:37:27 »
I note your excessive use of capital letters, and the fact that you still haven't got any relevant data; another hotel caught fire you say, that wasn't hit by an aircraft with 10,000 gallons of fuel, and didn't burn down? What does that prove?

I also note you seem to be surprised that fuel which has a equivalent energy of 450 tonnes of TNT could take down a structure like the world trade centre.

You are very good at parroting distorted information.

So now you concede it was only 10,000 gallons.  The plane wasn't FULL.

Is that equivalent energy based on a 100% efficient burn?  Open air fires can't burn with 100% efficiency.  That is why they produce carbon monoxide.  You are SO SCIENTIFIC with your Hypotheses.  LOL

But all of that is totally irrelevant to whether or not the conservation of momentum could have allowed the top of the north tower to crush the rest in less than 18 seconds.  You are going off topic.

psik
« Last Edit: 21/05/2009 00:12:25 by psikeyhackr »

#### L_D

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #65 on: 22/05/2009 11:47:18 »
I note your excessive use of capital letters, and the fact that you still haven't got any relevant data; another hotel caught fire you say, that wasn't hit by an aircraft with 10,000 gallons of fuel, and didn't burn down? What does that prove?

I also note you seem to be surprised that fuel which has a equivalent energy of 450 tonnes of TNT could take down a structure like the world trade centre.

You seem to think the aircraft impacts and the jet fuel is all that was needed to completely destroy those buildings, there has been two official reports so far and both (NIST and FEMA) concluded that the Towers survived both of these.

Ultimately it was ordinary office fires that officially brought down the Towers, that is why other highrise infernos ARE relevant, and there are many highrises that have burnt longer and hotter than the WTC Towers but none that have completely collapsed.

The NIST official account has approx 30% of the fuel exploding outside the building, and the rest burning off after a handful of minutes with it's main role being to ignite widespread office fires (FEMA had the jet fuel lasting 10 minutes).

These Towers were so strong they barely flinched when being hit by the aircraft and the accompanying jet fuel explosion, and yet after approx an hour later they both suddenly disintegrated all the way to the ground at a rate comparable to freefall, supposedly as a result of smouldering office fires.

As Psikeyhackr has said this is now going off track, he has raised a very important point and that is that the laws of C of M will not allow those upper portions to crush the much larger and stronger lower portions as fast as they did.

Even a C of M equation that assumes no losses, so is therefore unrealistically fast, will not allow such a fast collapse of the upper section simply because the sheer mass of the larger and undamaged lower portion HAS to significantly slow the falling mass.

#### psikeyhackr

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« Reply #66 on: 07/06/2009 21:54:05 »
What's happening out there?

Views have been going up for two weeks but no more responses.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #67 on: 09/06/2009 19:15:22 »
What's the point; you've made your mind up and USED UPPERCASE TO DO IT. Clearly if you've used upper case, then your point must be true.

#### psikeyhackr

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« Reply #68 on: 10/06/2009 15:15:06 »
What's the point; you've made your mind up and USED UPPERCASE TO DO IT. Clearly if you've used upper case, then your point must be true.

So where is your PHYSICS DEMONSTRATION MODEL to disprove my point?

SARCASM is great for debating but it is totally irrelevant to PHYSICS.

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #69 on: 10/06/2009 16:08:38 »
Yes, I agree with you that it's only physics if you're using uppercase. That's how all modern physics is done, and it's not a sign of possible mental instability at all.

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #70 on: 21/06/2009 21:34:22 »
Yes, I agree with you that it's only physics if you're using uppercase. That's how all modern physics is done, and it's not a sign of possible mental instability at all.

So two weeks and lots of hits but no other responses.

Are the people that come to this site interested in science or not?

Would you care to explain how innuendo or mental instability has anything to do with analyzing the physics of an event SEVEN YEARS AGO?

psik

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #71 on: 22/06/2009 02:34:04 »
Well, you know what they say; conspiracy theories can be fun.

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #72 on: 22/06/2009 03:16:01 »
Well, you know what they say; conspiracy theories can be fun.

Anyone that cares sufficiently can search the thread to see what I have said about any con______y th__ry.  All you can do is come up with psychological BS.   (3775)

(6-23=3851)(6-24=3916)(6-26=4062)(6-28=4148)(6-30=4233)(7-2=4295)
(7-4=4373)(7-6=4457)(7-8=4540)(7-10=4648)(7-12=4748)(7-15=4883)
(7-17=5007)(7-19=5096)(7-21=5159)

psik
« Last Edit: 21/07/2009 18:45:37 by psikeyhackr »

#### wolfekeeper

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #73 on: 23/06/2009 15:18:01 »
So, tell us again how you not bothering to model any of the correct stress or mass distribution in a 'test' proves that a building that fell down, couldn't have fallen down?

#### psikeyhackr

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #74 on: 24/07/2009 19:40:36 »
So, tell us again how you not bothering to model any of the correct stress or mass distribution in a 'test' proves that a building that fell down, couldn't have fallen down?

I need a long time to come up with an appropriate response to your deep intellectual input.

http://www.thenakedscientists.com/forum/index.php?topic=21925.msg253416#msg253416

It is impossible to make a model with correct stress and mass proportions without sufficient data.  The NIST doesn't even tell us the total amount of concrete in the towers.  If you watched my videos you will see I ask about the steel and concrete on every level. How can anyone build a model as you describe without that data?  (5244)
« Last Edit: 16/08/2009 00:44:58 by psikeyhackr »

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##### Conservation of Momentum in a Gravitational Collapse
« Reply #74 on: 24/07/2009 19:40:36 »