Merged Applicability of Bazant's model to the real world

[uke2se]

We already went through this in another thread. I did a random check of the sources listed, and found 3 or 4 of them supporting the Baznat/NIST findings. The others seemed unrelated, some of them presenting their own analyses. There was at least one listed in that spammed list that was a paper used, cited and rejected by NIST in producing the report. So how can you call that a paper in "support" of the official theory?

Whoever provided the list last time did not seem to understand the difference between scientific support versus the use of references.

As I recall, your "random check" was challenged and shown to be pure BS.

 

[ergo]

Oh, so it's not a universal physical principle following from Newton's Laws of Motion after all, that the resisting force must cause a deceleration?

If resisting forces don't cause a deceleration, what do they do?

Do you now admit that that causing a deceleration depends on which force is greater -- that is, in this case, that the force acting on Block C in the downward direction must be less than the resistive force of Block A, for Block C to decelerate? And do you now recognize that if the downward force on Block C is greater, it will not decelerate?

No, I don't. As I've already stated.

If so, we've made some progress. Please indicate your agreement with the above, and I will answer your question.

Please just show how the net force from block C exceeds the resistive force of Block A, without referring to Bazant. Thanks.

 

[ergo]

As I recall, your "random check" was challenged and shown to be pure BS.

I don't recall that. Please show where that occurred.

 

[uke2se]

Man, ergo is a stundie generation machine.

 

[uke2se]

I don't recall that. Please show where that occurred.

Nope. You brought up the other thread. You show how your "random check" showed what you claim it showed.

 

[ergo]

It's typical of bee dunkers to never actually back up anything they say...

 

[uke2se]

It's typical of bee dunkers to never actually back up anything they say...

So, will you be breaking twoofer tradition and actually back up what you say?

 

[cooperman]

Which forces, precisely, will be equal and opposite? When you answer that question correctly, you will see that it does not follow that it must cause a deceleration.

However, I doubt that you can answer it correctly, or would if you could. Care to surprise me?




Nope. You (and anyone) can read the posts, so there's no use lying about that. Ergo referred to Newton's laws of motion and basic principles of science. Newton's laws of motion or basic principles of science apply to tires, don't they?

I won't respond to the other part of your post which is itself off topic.

Respectfully,
Myriad

Which forces will be equal and opposite? Are you serious? When an object falls under gravity it accelerates at g due to the force of gravity. When it impacts another object then that object imparts an equal force onto the falling object in the opposite direction to gravity. At that instant the net forces are zero and the falling object is no longer accelerating. Why are you pretending that you don't know this?

Newtons laws of motion do indeed apply to tyres but they aren't the subject of the thread. ergo was not claiming that something with a resisting force can never accelerate, you made that up so you could slip your lame analogy in.

 

[Grizzly Bear]

If resisting forces don't cause a deceleration, what do they do?

Myriad from what I've been reading is referring to net acceleration which is pretty trivial if you're familiar with any kind of vector mathematics. If you have an acceleration in one direction and a "resisting force" (acceleration in the opposite direction) then we can consider the former one positive, and the latter negative.

Say for example you have a "positive" acceleration of 9.8 m/s/s and a resisting (AKA negative) acceleration of 3m/s/s. Your net acceleration would be 9.8-3 = 6.8 m/s/s meaning acceleration proceeds in the direction defined here as "positive"

Please just show how the net force from block C exceeds the resistive force of Block A, without referring to Bazant. Thanks.

Then you are ignoring the engineering principals entirely. Do you honestly think think that a mass of 15 floors will exert the same force when it's static, as it will when it's moving? The reason why the towers stand "firmly" in the "static" condition is because all net acceleration values are "0" meaning that it is not moving. That the net force is '0'. Meaning that the exerted weight of the floors is simply mg:

mg(+) vs mg(-) = 0 net force

Before I move on: Do not confuse "net values" with "absolute values"

Now, determining force for a moving mass is a bit more involved and I've already done the work: HERE

Now then, you also need to determine how this *jolt* derived from a limiting model is supposed to be applied to a condition like this:

Where you don't even have alignment.

This is why... we continue cautioning the use of the Bazant model literally.

 

[Myriad]

If resisting forces don't cause a deceleration, what do they do?

By definition, resisting forces act in the direction opposite some other force (or sometimes, but not in this case, a velocity) that they are said to be resisting.

Whether or not they cause a deceleration (that is, by the definition of deceleration being applied in this thread, a decrease in the magnitude of velocity) depends on whether or not the magnitude of the resisting force exceeds the magnitude of the force they are resisting.

No, I don't. As I've already stated.

Okay, but then you're wrong, as I've already stated. The correct understanding is: given a force F acting on a mass, the mass will accelerate. If you then add a resisting force R acting on the same mass, if F exceeds R in magnitude, the mass will continue to accelerate.

Please just show how the net force from block C exceeds the resistive force of Block A, without referring to Bazant. Thanks.

Since you will not acknowledge that whether or not the net force from Block C exceeds the resistive force of Block A makes a difference in whether or not a deceleration is expected to occur, that question remains irrelevant.

Respectfully,
Myriad

 

[cooperman]

By definition, resisting forces act in the direction opposite some other force (or sometimes, but not in this case, a velocity) that they are said to be resisting.

Whether or not they cause a deceleration (that is, by the definition of deceleration being applied in this thread, a decrease in the magnitude of velocity) depends on whether or not the magnitude of the resisting force exceeds the magnitude of the force they are resisting.




Okay, but then you're wrong, as I've already stated. The correct understanding is: given a force F acting on a mass, the mass will accelerate. If you then add a resisting force R acting on the same mass, if F exceeds R in magnitude, the mass will continue to accelerate.




Since you will not acknowledge that whether or not the net force from Block C exceeds the resistive force of Block A makes a difference in whether or not a deceleration is expected to occur, that question remains irrelevant.

Respectfully,
Myriad

The bolded portion is categorically wrong.

If I drop a block of wood on to the floor. When it hits the floor it stops dead. It decelerates. But, the resisting force from the floor is only equal to the force the wood exerts on the floor. There is not a greater resistive force but the block decelerates.

What you haven't factored in is that Force=ma. R might not exceed F, in your example, but if the object imparting the R force is more massive then it will create a deceleration.

 

[Grizzly Bear]

Do not confuse "net values" with "absolute values"

.........

 

[femr2]

The bolded portion is categorically wrong.

If I drop a block of wood on to the floor. When it hits the floor it stops dead. It decelerates. But, the resisting force from the floor is only equal to the force the wood exerts on the floor. There is not a greater resistive force but the block decelerates.

The floor is resting upon something somewhat a little bit larger than the brick. It is not a cube

Try dropping a brick onto a piece of tissue paper strung above ground between two sticks and ask yourself what happens. Does the tissue paper cause the brick to decelerate ?

I suggest the entire discussion is split out. It's ridiculous.

(And it's also put my questions to Tony back a page. Haven't forgotten them Tony. Will ask again when you pop back.)

 

[cooperman]

The floor is resting upon something somewhat a little bit larger than the brick. It is not a cube

Try dropping a brick onto a piece of tissue paper strung above ground between two sticks and ask yourself what happens. Does the tissue paper cause the brick to decelerate ?

I suggest the entire discussion is split out. It's ridiculous.

(And it's also put my questions to Tony back a page. Haven't forgotten them Tony. Will ask again when you pop back.)

I was simply refuting what myriad said about the need for a greater resistive force to create deceleration.

Do you agree that when a block of wood hits the floor the force acting on it is the same as the force it imparts on the floor. The forces are equal but the block does indeed decelerate.

 

[ozeco41]

Again your explanation falls short....

Nonsense - I haven't given an explanation merely identified one alternate factor which you decline to address and reject without supported reasoning.

If what you say were true the spires would not be made up of predominantly inner core columns....

Please don't misinterpret me to support your nonsense.

...The more likely explanation for it is that the outer core columns were removed and at the upper levels the inner columns would be pulled down with them until the inner columns were strong enough to withsatnd the pull...

..once again you repeat your totally unsupported fantasy.

I think you are hypocritical in accusing me of using ad hominem while you sit there and call me a truther...

False. I never called you a truther. I identified that the false arguments you use are standard truther ploys.

I am an engineer who calls it like he sees it,...

Actually I think that is true. Be aware that I spent many years managing engineers and it is quite common for some of them to fixate on a narrow and illegitimate portion of a scenario when the total scenario is more complex. However you have had the benefit of competent engineers pointing out to you some of the bits that are not in the frame when you "call it as you see it".

...and there are no ploys about it.

The "ploys" are there alright. Maybe you don't intend them. But the structure of your logic regularly uses logical flaws which I identify as "standard truther ploys".

 

[femr2]

I was simply refuting what myriad said about the need for a greater resistive force to create deceleration.

Do you agree that when a block of wood hits the floor the force acting on it is the same as the force it imparts on the floor. The forces are equal but the block does indeed decelerate.

LOL.

It's a collision between a brick and a planet.

Think about it.

Start with "frame of reference", and do it on another thread please.

 

[Myriad]

Newtons laws of motion do indeed apply to tyres but they aren't the subject of the thread. ergo was not claiming that something with a resisting force can never accelerate, you made that up so you could slip your lame analogy in.

Actually that is exactly what he was and is claiming. I don't blame you for finding that hard to believe though.

Which forces will be equal and opposite? Are you serious? When an object falls under gravity it accelerates at g due to the force of gravity. When it impacts another object then that object imparts an equal force onto the falling object in the opposite direction to gravity. At that instant the net forces are zero and the falling object is no longer accelerating. Why are you pretending that you don't know this?

I asked because I expected you to give the wrong answer, but I didn't want to assume that you would. Now that you have, I'll tell you what you got wrong.

When an object falls under gravity near the earth's surface, and no other forces apply to it, it accelerates at g. That force is due to the earth pulling on the object, and the acceleration g is a constant in part because the earth's mass is (not perfectly, but nearly perfectly) constant. The magnitude of that force is mg, where m is the mass of the object.

At the same time, by Newton's second law of motion, an equal and opposite force acts upon the earth. Earth is pulled toward the falling object, with the same force mg. That's a pair of equal and opposite forces.

When it impacts another object, then it imparts a force on that object, and the object imparts an equal and opposite force on it. That's another pair of equal and opposite forces.

But the magnitude of the impact force depends on the nature of the impact and the impacting objects. Clearly, if the falling object is a hammer, the force it imparts on the impacting object and the force the object it hits and the force the object imparts on it will be different if the object is, say, an anvil versus a rice krispie.

Your error is a completely unjustified assumption that the two forces that are actually acting on the falling object, the force of gravity and the force the object it hits imparts on it, must be equal. They do not represent a pair of equal and opposite forces.

Gravity is one force acting in the scenario (acting equally and oppositely between the earth and the falling mass, and depending on the mass of the earth, the mass of the object, and their distance); the impact force is another (acting equally and oppositely between the two colliding objects, and depending on the relative velocity, the objects' masses, and their strength and elasticity). Except insofar as both depend in part on the mass of the falling objects, the magnitude of the two pairs of forces are based on entirely different parameters.

That's why the "net force equals zero" argument is invalid.

Respectfully,
Myriad

 

[cooperman]

Actually that is exactly what he was and is claiming. I don't blame you for finding that hard to believe though.




I asked because I expected you to give the wrong answer, but I didn't want to assume that you would. Now that you have, I'll tell you what you got wrong.

When an object falls under gravity near the earth's surface, and no other forces apply to it, it accelerates at g. That force is due to the earth pulling on the object, and the acceleration g is a constant in part because the earth's mass is (not perfectly, but nearly perfectly) constant. The magnitude of that force is mg, where m is the mass of the object.

At the same time, by Newton's second law of motion, an equal and opposite force acts upon the earth. Earth is pulled toward the falling object, with the same force mg. That's a pair of equal and opposite forces.

When it impacts another object, then it imparts a force on that object, and the object imparts an equal and opposite force on it. That's another pair of equal and opposite forces.

But the magnitude of the impact force depends on the nature of the impact and the impacting objects. Clearly, if the falling object is a hammer, the force it imparts on the impacting object and the force the object it hits and the force the object imparts on it will be different if the object is, say, an anvil versus a rice krispie.

Your error is a completely unjustified assumption that the two forces that are actually acting on the falling object, the force of gravity and the force the object it hits imparts on it, must be equal. They do not represent a pair of equal and opposite forces.

Gravity is one force acting in the scenario (acting equally and oppositely between the earth and the falling mass, and depending on the mass of the earth, the mass of the object, and their distance); the impact force is another (acting equally and oppositely between the two colliding objects, and depending on the relative velocity, the objects' masses, and their strength and elasticity). Except insofar as both depend in part on the mass of the falling objects, the magnitude of the two pairs of forces are based on entirely different parameters.

That's why the "net force equals zero" argument is invalid.

Respectfully,
Myriad

That is a very nice wall of text, but the bottom line is that you are wrong when you claim that the resistive force R must be greater than F to cause a deceleration.

You seem to think that acceleration and force are interchangeable and equivalent. They aren't. It depends on the mass of the objects causing the forces.

When my block of wood hits the ground, R and F are the same, but the block decelerates. Yes, or no?

By the way, when an anvil hits a rice krispie they do indeed impart equal and opposite forces on each other. If you don't agree , ask sylvia browne to contact Isaac Newton for you and thrash it out with him.

I now agree with ergo. The lack of understanding of the most basic laws of science here is frightening.

 

[Myriad]

If I drop a block of wood on to the floor. When it hits the floor it stops dead. It decelerates. But, the resisting force from the floor is only equal to the force the wood exerts on the floor. There is not a greater resistive force but the block decelerates.

You have just shown that the resistive force exceeds the force of gravity on the block. So net force is decidedly not zero. (If it were, the block would not stop, it would keep going through the floor.)

That's why the block decelerates from its maximum v to zero, when it hits the floor, in much less time than it took to accelerate from zero to its maximum v while it was falling after you dropped it. The same change in the magnitude of v, in less time, means greater acceleration and hence greater force.

As before, let's properly pair up the forces involved.

The gravitational pull of the earth on the hammer, and the pull of the hammer on the earth, are equal and opposite. That's one pair of forces.

The impact force of the block on the floor, and the impact force of the floor on the block, are also equal and opposite. That's a different pair of forces.

So, which of those forces are acting on the block when it hits the floor? The force of gravity is pulling it down; the "resistance" of the floor is pushing it up. In this case the latter is much greater in magnitude so the block decelerates quickly to zero.

Note that this means that the force the block applies to the floor when it hits (which is the equal-opposite pair of the force the floor applied to the block, that changed the block's velocity in a short time) significantly exceeds the force of gravity pulling down on the block -- that is to say, the block exerts a force on the floor that significantly exceeds the block's weight. That's that "dynamic load" thingie that is often spoken of here.

If the block were made of 100 pounds of lead, and the floor were made of balsa wood, the result would be different. So again: whether or not the falling object decelerates depends on whether or not the resistive force exceeds the gravitational force pulling the object down.

Respectfully,
Myriad

 

[R.Mackey]

That is a very nice wall of text, but the bottom line is that you are wrong when you claim that the resistive force R must be greater than F to cause a deceleration.

You seem to think that acceleration and force are interchangeable and equivalent. They aren't. It depends on the mass of the objects causing the forces.

When my block of wood hits the ground, R and F are the same, but the block decelerates. Yes, or no?

By the way, when an anvil hits a rice krispie they do indeed impart equal and opposite forces on each other. If you don't agree , ask sylvia browne to contact Isaac Newton for you and thrash it out with him.

I now agree with ergo. The lack of understanding of the most basic laws of science here is frightening.

This has to be a simple troll.

Newton's Second Law, chum. Learn it. But not from me. You earn my coveted Ignore.