If it doesn't agree with experiment, it's wrong. Part II

[Redwood]

Originally Posted by Redwood
But that's not what we're discussing! A falling brick is under constant acceleration due to gravity and when it (or any other weighty object) strikes something as insubstantial as tissue paper, the paper can't even slow it down, (i.e. make dv/dt negative)it can merely briefly reduce the acceleration to less than g (i.e. da/dt becomes negative) Something more substantial, like a pane of glass, will reduce the velocity (dv/dt becomes negative).

Why are you contradicting yourself? You claim I'm right, but then you say the paper can't even slow the brick down. You are playing the semantics game. You admit that the rice paper will reduce the acceleration at the instant of impact. Why does it matter if the velocity won't substantially change? What are you trying to prove?

There is no contradiction. The apparent contradiction results from the confusion in your own mind. You cannot understand the difference between reduced acceleration and reduced velocity. And, no, I'm not playing a "semantics game". I used elementary differential calculus to avoid semantics. (That's why real scientists and engineers use mathematics; it's not just for doing calculations.)

I'll make one last try to help you understand. Let's take a case where there are no impacts at all with solid objects:

Let's do a Galileo and drop a cannon ball from the top of the Tower of Pisa. Neglecting air resistance, it will hit the ground in ~8.5 seconds at a velocity of ~83 m/sec. It will be accelerating throughout the drop, that is dv/dt will always be positive.

However, it will not hit the ground exactly on time. Collisions with air molecules on the way down will reduce its acceleration just a tiny bit. So tiny that it can be neglected for all practical reasons. But it's there. A high-speed camera with a rate of 10⁶ fps could detect the loss of acceleration, but it's doubtful that even a high-resolution 30 fps camera could.

Which means that for the entire drop:

dv/dt will always be positive. dv/dt² will always be negative. If you think about it, since air resistance increases with velocity, this means that the loss of acceleration will be greater at the end of the drop than at the start. Meaning: dv/dt³ will always be negative, too!
Think about this, FF. Contemplate it. Run it through your mind as you prepare for bed. Someday, you may understand. It's possible, in principle.

SO: Falling objects can experience either a reduction or increase in velocity, a decrease in the increase of velocity, and even an increase in the rate of decrease of the increase of velocity, depending on what they fall through.

So now the money question: What does this have to do with the progressive collapses of the Twin Towers? The answer is, ABSOLUTELY NOTHING!

A progressive collapse can proceed with either an actual decrease in velocity at each floor, or a mere reduction in the acceleration. Which means that Newton's Laws of Motion are useless for studying the WHY of a progressive collapse! Resort must be taken to other physical laws.

Newton's Law of Gravitation DOES get star-billing and enters the stage at the very beginning, but then exits and is off-stage for the rest of the play. The rest of the play involves other physical laws.

 

[Redwood]

Let me amplify just a bit on my last post. Drop bowling balls of the same weight from the same height onto (1) a trampoline (2) a pane of glass (3) a block of granite.

In case one, the ball bounces up and down on the trampoline and eventually comes to rest. In case two, the ball breaks through the glass and continues. In case three, the bowling ball shatters against the granite.

Newton's Laws of Motion (and his Law of Gravitation) describe what happened in all three cases, but they do not explain why the three cases are different. Other physical laws must be used.

 

[jaydeehess]

. You admit that the rice paper will reduce the acceleration at the instant of impact. Why does it matter if the velocity won't substantially change? What are you trying to prove?

Think about what you just posted there FF.

If the velocity at which the paper hits is sufficient to break through the paper, and the brick then drops further, accelerating again at g, through the same distance as the first drop, then it is AT LEAST moving at the same velocity as it was at that first impact. If that first impact was fast enough to break through the paper the it is sufficient to break the second, EVEN IF the paper was sufficient to substantially change the velocity, EVEN IF the first impact was sufficient to reduce velocity to zero while also destroying the paper.

IF after first impact the paper impact did not "substantially change" the velocity of the brick, then it accelerates to next impact from the velocity it had after having passed through the first paper. Thus it hits at even greater velocity than it hit the first paper.

 

[jaydeehess]

Let me amplify just a bit on my last post. Drop bowling balls of the same weight from the same height onto (1) a trampoline (2) a pane of glass (3) a block of granite.

In case one, the ball bounces up and down on the trampoline and eventually comes to rest. In case two, the ball breaks through the glass and continues. In case three, the bowling ball shatters against the granite.

Newton's Laws of Motion (and his Law of Gravitation) describe what happened in all three cases, but they do not explain why the three cases are different. Other physical laws must be used.

Yes! The scale, the relative magnitudes of parameters used, has changed, therefore different results.

 

[rwguinn]

Yes! The scale, the relative magnitudes of parameters used, has changed, therefore different results.

I can bend a 4 foot long 1/4 inch diameter steel rod in my hands.
if I try that with a 1/2 inch diameter rod, I'll have to use 16 times the force to bend it the same amount
Scaling. It's important.
And
Gravity doesn't scale

 

[beachnut]

I can bend a 4 foot long 1/4 inch diameter steel rod in my hands.
if I try that with a 1/2 inch diameter rod, I'll have to use 16 times the force to bend it the same amount
Scaling. It's important.
And
Gravity doesn't scale

Have you tried the moon? Or would it be Jupiter. Do we need more g, or less g to scale a failed model like Cole's, scaled for gravity...

Come to think of it, scaling gravity... skip it - scaling the refrigerator for a beer is my next quest. Kill brain cells, skip using them... 9/11 truth time.

 

[jaydeehess]

I can bend a 4 foot long 1/4 inch diameter steel rod in my hands.
if I try that with a 1/2 inch diameter rod, I'll have to use 16 times the force to bend it the same amount
Scaling. It's important.
And
Gravity doesn't scale

Which is the point of course (not that you didn't know it.).

If one builds and exact 1/1000 scale model of the WTC tower it WILL, it MUST, behave differently than the full as-built, tower. gravity cannot be scaled, its always going to be the same (as long as we are speaking of being on the surface of this planet, just as the towers were).
AND
the square-cube law comes into effect.

This must be taken into account in detail that depends on the use of the model.

If its just to look at then a simple 1:1000 scale model will suffice, if you are attempting to garner forensic information,,,,,,.,,,,,,,

 

[beachnut]

Use a g simulator with the model under g force. We pulled 7.33 g in the T-38 chasing clouds, the top limit. How many gs are needed to for a scale model.

 

[rwguinn]

Which is the point of course (not that you didn't know it.).

If one builds and exact 1/1000 scale model of the WTC tower it WILL, it MUST, behave differently than the full as-built, tower. gravity cannot be scaled, its always going to be the same (as long as we are speaking of being on the surface of this planet, just as the towers were).
AND
the square-cube law comes into effect.

This must be taken into account in detail that depends on the use of the model.

If its just to look at then a simple 1:1000 scale model will suffice, if you are attempting to garner forensic information,,,,,,.,,,,,,,

And to really **** 'em up, demonstrate bending with a thin sheet, first in the "thin" direction, and then in the "wide" direction.

Miraculously, the worst deflection is perpendicular to the applied force direction! Newton missed that one, huh?

 

[Redwood]

Originally Posted by Redwood
Let me amplify just a bit on my last post. Drop bowling balls of the same weight from the same height onto (1) a trampoline (2) a pane of glass (3) a block of granite.

In case one, the ball bounces up and down on the trampoline and eventually comes to rest. In case two, the ball breaks through the glass and continues. In case three, the bowling ball shatters against the granite.

Newton's Laws of Motion (and his Law of Gravitation) describe what happened in all three cases, but they do not explain why the three cases are different. Other physical laws must be used.

Yes! The scale, the relative magnitudes of parameters used, has changed, therefore different results.

It's actually the physical characteristics of the impacted targets. The trampoline is "springy", so it has quite a bit of yield (what physicists call "elastic deformation"), and the velocity (hence the momentum) of the bowling changes over a much longer period of time than in the other two cases. Since force = dp/dt, the force of impact is less than the other two, though the velocity, kinetic energy, and momentum of all three are the same.

Glass is very slightly springy, but not so much that it isn't easily pushed past its elastic deformation limit and its "plastic" deformation limit and it shatters.

Granite really isn't springy at all, and neither are bowling balls, so both experience a brief but very large force. Granite has enormous strength but bowling balls don't, so the ball shatters but the granite doesn't, unless the ball is dropped from enormous height, in which case both are destroyed. (I was thinking of backyard-type experiments here. )

You could add a fourth variation: Drop a "medicine ball" of the same weight as the bowling ball onto the granite. In this case, the medicine ball has enough yield so that again the force of impact is less, and the ball squishes out but regains its shape and both it and the granite survive, though in all four cases the velocity, momentum, and kinetic energy are the same. But the forces of impact are all different.

But I repeat again: Newton's Laws of Motion are useless for analyzing the "WHY" of a progressive collapse! Other physical laws are in play here. The whole Truther discussion of "Newton's Laws" is a huge red herring!

Science is a case of ever-deepening levels of understanding. Even Newton's Law of Gravitation describes the effects of gravity, but does not explain the why of gravity. That was left to Einstein.

 

[pgimeno]

But I repeat again: Newton's Laws of Motion are useless for analyzing the "WHY" of a progressive collapse! Other physical laws are in play here. The whole Truther discussion of "Newton's Laws" is a huge red herring!

Agreed.

During FalseFlag's suspension there was a discussion about the forces caused by debris-on-floor impacts due to conservation of momentum. In a straightforward idealized case (perfectly rigid bodies and perfectly plastic collision in a direction normal to their surfaces), the accelerations involved would be infinite. Since that idealized case seems to be the one under discussion, and infinite acceleration implies infinite forces involved, analysing the problem from a forces perspective can be quite tricky. We'd be forced to introduce elasticity and it gets pretty hard to give any realistic estimations.

ETA: The forces involved in the deceleration due to conservation of momentum can be much bigger than those discussed so far. I think that post 234 may be wrong for that reason, unless it considers elasticity.

ETA2: Case in point to better identify what I'm talking about: Newton's cradle. Consider the deceleration of the dropped ball as it hits the next. It's huge.

 

[jaydeehess]

Redwood , elasticity of an object would be a "parameter" that can be altered.

I have tried several times to note to truthers that Newton F=ma was originally expressed in terms of momentum and time. As you noted:
F = dp/dt

 

[ozeco41]

Which brings me to the big point:

Actually it is NOT the big point for the current discussion - tho it is the big point you want to make and you are right. It is probably the second ranking big point for this current discussion.

At risk of some member(s) once again missing the point and seeing the need to chastise me for my lack of engineering perception.

Newton's Laws of Motion are useless for explaining the why of progressive building collapses.

TRUE - Newtons laws come into play no higher than three levels down the hierarchy of explanation. Stage Three if your reasoning doesn't do "levels" of taxonomy.

Step ONE - top level - describe WHAT is the mechanism of the collapse. Until we ("you") know what we are talking about discussion of details is meaningless. One person describing an apple and the other talking about bananas - or even worse rabbits. Which leads to people getting somewhat confused about the fur of a banana - or how the banana has four legs. (And - yes - the metaphor - tho' it is an accurate reflection of the sort of discussions we see - will throw a lot of members.)

Other physical laws must be used.

We are still a couple of steps short of needing or even being able to use physical laws. We haven't decided what we are talking about.

Coles models are all variants on "Columns in Line" mechanisms. They DO NOT represent WTC Collapses which did not have "columns in line" THEREFORE they are invalid. We are off the rails some steps before we get interested in scaling or the application of Newton's Laws. It needs very risky mental gymnastics to even discuss "columns in line" nonsense as if it is relevant to WTC. And yes - I'm frustratingly aware of the reasons why members on this forum are reluctant to face that simple fact.

The real event WTC Twin Towers collapses - in the progression stage - bypassed the columns.

And - as I said a few dozen posts back - members are pussy-footing around that fact.

Now if any members want to chastise me for that statement please make sure you understand the point. There are two commonly used models of mechanisms for Twin Towers progressions. The real event - what really happened with columns bypassed and therefore is what should be used to discuss the actual Twin towers progression stage and models such as Cole publishes which are W_R_O_N_G - they had/have the columns in line and are useless for describing the Twin Towers real event.

So anyone who wants to disagree with me AND elicit some response from me please:

A) Prove me wrong on the model - show that the real event had "columns in line" and support with reasoning for why you have columns in line as your model AND
B) Prove me wrong on "pussy-footing" - list the members and link the posts where members other than me (and I think JDH) are insisting that we decide which model we are prattling on about.

Coles models are all of the wrong mechanism.

IF there is one model explicitly in the frame (Or even BOTH models being explicitly dealt with in parallel - maybe compare and contrast) we can have meaningful discussion of the effects of scale applied to the topic of valid or invalid models.

(I'm sure that Ozeco especially appreciates this. )

More than even you realise Redwood - but thanks for the thought.

 

[jaydeehess]

A lot of the discussion concerned whether or not Cole's model demonstrates his understanding of Newton is correct.

While ozeco correctly points out that none of these models reflects mechanisms in action in the towers, that is not strictly what FF was saying.

Then again the brick/paper, and others do isolate one part of collapse. Destruction of "floors" by massive overload. By altering a single model parameter one can get a polar opposite result, thus also illustrating Cole is wrong.

 

[ozeco41]

A lot of the discussion concerned whether or not Cole's model demonstrates his understanding of Newton is correct.

While ozeco correctly points out that none of these models reflects mechanisms in action in the towers, that is not strictly what FF was saying.
Then again the brick/paper, and others do isolate one part of collapse. Destruction of "floors" by massive overload. By altering a single model parameter one can get a polar opposite result, thus also illustrating Cole is wrong.

FF is not saying anything "strictly". He is game playing looking for bites.

I'm into addressing the bits of real issue he raises - not chasing him all over the universe of his derails and other tricks.

And I'm well aware of the depth of the rabbit burrows.

 

[PhantomWolf]

The real event WTC Twin Towers collapses - in the progression stage - bypassed the columns.

And - as I said a few dozen posts back - members are pussy-footing around that fact.

I'm not sure who these members are, to my knowledge most debunkers use the model of the upper block falling onto the floor pans overwhelming the connectors and bending them down so that the floor then collapsed down with the upper block.

I don't think I have ever seen any debunkers using a model where the columns of the upper block fell onto the columns of the lower tower. The only model I have seen that does that is one that is used purely as an upper limit of the energies of the collapse so as to prove that even if the best case for the towers to survive occurred by the columns falling onto columns (it didn't) the towers still would have collapsed.

 

[GlennB]

The real event WTC Twin Towers collapses - in the progression stage - bypassed the columns.

And - as I said a few dozen posts back - members are pussy-footing around that fact.

You hint at this this pretty often (suggesting debunkers here have Bazantian leanings, and similar) so I have to conclude we've been reading different forums for years. Column-to-column impacts are sometimes discussed but only in strictly theroretical/technical terms - virtually everybody on the debunking side has accepted for a long time that collapse of the floors was the driving force for global collapse.

In fact the idea of column-to-column impact is generally derided by members here and its great unlikelihood has been the very source of all the flak thrown at Szamboti and other CTists in endless 'missing jolt' discussions.

 

[Crazy Chainsaw]

You hint at this this pretty often (suggesting debunkers here have Bazantian leanings, and similar) so I have to conclude we've been reading different forums for years. Column-to-column impacts are sometimes discussed but only in strictly theroretical/technical terms - virtually everybody on the debunking side has accepted for a long time that collapse of the floors was the driving force for global collapse.

In fact the idea of column-to-column impact is generally derided by members here and its great unlikelihood has been the very source of all the flak thrown at Szamboti and other CTists in endless 'missing jolt' discussions.

True, I wanted help to develop a correct computer generated collapse model by updating the Greening model with what we now know since the Greening model actually used floor stripping to do the work of connection sheering it appears it would have been easy.

However after Oz accused me of worshipping the Greening, Benson, Banzant paper I dropped the whole project, an do not intend going back to it now, too busy to do so.

 

[FalseFlag]

Why do you keep bringing up scale?

Because your posts sound fishy.

Well done.

I guess you could say I just can't avoid the "lure" to "troll".

 

[FalseFlag]

Your claim that G⁺ = N^- is simply incorrect.

I agree that your model is more correct, when Newton's third law is being discussed.

You are right that I had a misconception about all of the forces involved when discussing Newton's third law of motion.

The most simple way to explain it is, if the forces are acting on one object, they are not action-reaction pairs.

Once again, you were right, and I did misunderstand this one concept.

Consider this. A Sky Diver jumps out of a plane. Gravity is applying a force to the skydiver. According to Newtons 3rd Law, there must be an opposite and equal force to this. Since the skydiver is in freefall there is no Normal Force, so what is the equal and opposite force demanded by the 3rd Law?

Should we ignore air resistance? I think your example requires me to.

The equal and opposite force is the force the skydiver exerts on the earth. The earth's gravity pulls the skydiver down, and the skydiver pulls the earth towards himself or herself. Since the forces are equal (but opposite), and the mass of the earth is so much greater than that of the skydiver, the acceleration of the earth towards the skydiver is negligible. It's there, but unnoticeable.

One last time, you were right about action-reaction pairs.
I emphasized that last statement as much as I could so you could gloat as much as possible. You skeptics aren't right too often, so you really should enjoy this one as much as you can.