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

[FalseFlag]

Now, can you finally see that the gravitational force the earth exerts upon the building is equal and opposite to the gravitational force the building exerts upon the earth?

Yes, I have already made the necessary corrections.

 

[Belz...]

Yes. Scale does not matter if you are only trying to replicate the motions observed during the collapses.

Given that stuff smashes through other stuff and their relative strength matters, yes, scale matters a whole damn lot.

 

[FalseFlag]

Oh, no. It's YOUR misunderstanding. It isn't as common as you might think.

I guess that's the title of the video is "A Common Misconception about Newton's Third Law Force Pairs (or Action-Reaction Pairs)"

https://www.youtube.com/watch?v=wmmjfbl7zG4&feature=youtu.be

Just because you want a statement to be true doesn't mean it is.

 

[FalseFlag]

Ah, yes. Anti-intellectualism. The hallmark of a true thinker!

I'm sorry that you are one of their victims, and that you can't see it.

 

[Crazy Chainsaw]

Yes, I have already made the necessary corrections.

Then you can determine the reaction forces will be weeker in the lower structure,
So much weaker it would be like you jumping from a diving board into a swimming pool.

There would be resistance, but not much because the magnitude governs the energy value of G, and that is why G can not be scaled.

 

[Belz...]

I'm sorry that you are one of their victims, and that you can't see it.

The only victim here is you; a victim of your own sense of self-importance. You know next to nothing about physics, and yet you pretend to know better than anyone else. Naturally this leads you to a conspiracy theory, as if experts and professionals have nothing better to do but lie about their job in order to make it complex and obfuscate reality, and people like you are what we need to remove that veil of dishonesty and expose the truth.

No, the problem is that your understanding of physics is incomplete, and it paints a simpler picture than what reality is, and this hampers your ability to properly interpret these events and Cole's video.

It's like someone who has not the slightest idea of how computers are programmed, telling me, a computer programmer, that people in my field are making programs needlessly complex to prevent regular people from making their own games, something he is convinced can be done by a few keystrokes like in those 80s movies.

Reality is complex, even more so with technology and civilization. It's not surprising that we need experts who spend years learning a particular field in order for us to understand and use that field fully. That you don't understand that field doesn't mean that someone's being deceptive: the problem lies entirely with your own knowledge.

 

[Crazy Chainsaw]

The only victim here is you; a victim of your own sense of self-importance. You know next to nothing about physics, and yet you pretend to know better than anyone else. Naturally this leads you to a conspiracy theory, as if experts and professionals have nothing better to do but lie about their job in order to make it complex and obfuscate reality, and people like you are what we need to remove that veil of dishonesty and expose the truth.

No, the problem is that your understanding of physics is incomplete, and it paints a simpler picture than what reality is, and this hampers your ability to properly interpret these events and Cole's video.

It's like someone who has not the slightest idea of how computers are programmed, telling me, a computer programmer, that people in my field are making programs needlessly complex to prevent regular people from making their own games, something he is convinced can be done by a few keystrokes like in those 80s movies.

Reality is complex, even more so with technology and civilization. It's not surprising that we need experts who spend years learning a particular field in order for us to understand and use that field fully. That you don't understand that field doesn't mean that someone's being deceptive: the problem lies entirely with your own knowledge.

His own video proves your right hilarious another self debunking.

 

[Crazy Chainsaw]

Yes. Scale does not matter if you are only trying to replicate the motions observed during the collapses. Scale absolutely does matter if you are trying to duplicate structural behavior. Direction of acceleration, direction of net forces, and similar sequences of the direction of net forces are NOT structural behavior.

Do not take my statement out of context by only copying and pasting a few words in order to promote your own incorrect argument.

How can you replicate the motions without correct energy Values that is a question you have too solve to prove your conjectures?

 

[PhantomWolf]

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.

Thank you, nice to hear.

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.

Good. I am glad that you have learned something new.

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.

No gloating, I understand how hard admitting you are incorrect is, but on this board doing so isn't a mark of failure, it's considered a mark of honour to admit it when you get things wrong. This is how we learn and grow. You'll actually gain a lot of respect among the posters here for doing so.

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

I pulled this part out because now that we've established the correct force pairings we can talk about acceleration compared to free fall in a vacuum.

If we take our skydiver, we know that if they were falling through a vacuum they would accelerate at ~9.8 m/s². Of course since they aren't, they won't be, it'll be less than that. So what causes it?

As they fall through the air, their body weight creates a force on the air molecules as it falls, and in return the air molecules press up making a force on the falling body. This is as you stated, air resistance.

So we have two force pairs, gravity pulling the sky diver down, and the resistance of the air pushing the sky diver up.

This means to determine the Sky Diver's acceleration, we need to need to consider both forces on them. We know that g is 9.8 m/s² towards the earth, so as long as our Acceleration upwards by Resistance (F_AR/m_diver) is less than 9.8 m/s², then the overall force the Skydiver feels is towards the Earth and they accelerate. Of course as they get faster, the Air Resistance increases, and once our F_AR is equal to F_g, then our sky diver reaches Terminal Velocity and they stop accelerating.

As you can see, they have a constant upwards force on them, but at no time do they actually decelerate during the fall, they merely have a reduced acceleration.

Now when they open their chute, they massively increase their F_AR and momentarily it is above F_g. At this point they have more force pushing them upwards than they have pulling them down, so their overall Force is up, and their velocity slows. They have a negative acceleration, or if you will, they decelerate. Of course as their velocity decreases, their F_AR also decreases until it reaches F_g and they reach Terminal velocity again, though now at a greatly reduced velocity.

Hopefully you can now follow this, and apply this knowledge to other situations, for example bricks falling through paper, or large blocks of rubble falling through floor pans.

 

[WilliamSeger]

How do they matter in any experiment involving similar accelerations, similar directions of net forces and similar sequences of net forces? Please provide a link to a credible source that supports you claim.

The question you should be asking is how can an experiment that ONLY involves "similar accelerations, similar directions of net forces and similar sequences of net forces" possibly tell you anything about the collapse of the WTC towers? You simply refuse to comprehend that it takes more than that. In all of Cole's experiments, some falling weight hits some representation of a floor and the floor ether fails or it doesn't. If it fails, everything falls and hits the next floor, which also either fails or it doesn't. Those individual outcomes are what determines the "motion" you say Cole is studying, but what, exactly, is determining the outcome of each of those events? Clearly, a floor only fails when the available force exceeds the floor's capacity, yet NOWHERE does Cole estimate either of those factors in his model or in the WTC towers, and NOTHING in your list of similarities even remotely suggests that there should be any similarity with force-vs-strength ratios. It's really the only thing that matters for what Cole is claiming to do with his models, and not only does he not address it, he is apparently clueless as to why he should.

You have been given several "credible sources" that discuss the scaling problem in structural and dynamic modeling, so that game is unplayable now.

 

[Porkpie Hat]

How do they matter in any experiment involving similar accelerations, similar directions of net forces and similar sequences of net forces? Please provide a link to a credible source that supports you claim.

It's incredible how you seem to be on the verge of understanding what many have been telling you then slip right back into blissful ignorance in the blink of an eye.

It matters for the same reason pushing a toy car off the kitchen table doesn't accurately represent a car being off a 300' cliff. It matters for the same reason a squirrel can jump meters with no adverse effects yet an elephant can't jump 15' into the air without doing lethal harm to itself.

And seriously, you have posted credible links that DON'T support your arguments all along. This has been pointed out to you in every way imaginable and you've just hand waved it away pretending your understanding of these issues supersedes everyone who disagrees with you yet you still don't seem to have even a tenuous grasp on the real world physics of the event.

Go to the nearest university with a physics or engineering department. Show your Cole video to some profs and students. Give your interpretation on why Cole's experiments prove...?...then ask yourself why you get pretty much the exact same answers you did here.

 

[PhantomWolf]

No you shouldn't ignore air resistance, it was a significantly important part of what slowed the Towers collapses, and slowed the fall so much.

We weren't talking about the towers, we were talking about a sky diver and the matching gravity forces. Air resistance wasn't relevant to that step, just the next.

 

[Porkpie Hat]

Oh and btw FF, if scale doesn't matter in Cole's experiments you should be able to replace the 10-20lb mass with an elephant and get the exact same results.

 

[pgimeno]

Remember, Newton's third law of motion says that for every action there is an equal and opposite reaction. The fact that the objects don't stop because of the action and reaction means nothing.

You seem to be making the same mistake again. Newton's First Law says that if they accelerate (or decelerate), it's because the forces are not in equilibrium, therefore they are not equal and opposite. This should be bleeding obvious. There's a limit to how much opposing force the connections can exert to oppose the movement of the falling floor. Past that, you get acceleration (=imbalanced forces). That's a case where the magnitude of N+ and N- does not equal that of G+ and G- (using PhantomWolf's terminology).

Remember that the object to which third law applies in the case of gravity is the Earth, not the impacted floor. You have forgotten that point again in the paragraph above. N- is not necessarily equal to G+. It will be until the connection gives way. Past that, they won't, and you'll get acceleration.

A bug and a truck can collide. The bug will exert a force on the truck. The truck will exert a force on the bug. The forces will be equal in the opposite direction. This is a fact. The bug will go splat, and the truck will not stop.

But the glass doesn't break in this case, meaning the glass could exert enough opposing force to stop the bug. If it broke, it would mean that the forces were not equal, and the glass could not exert enough force to arrest the force imposed by the bug. That would mean an imbalance of forces.

You should review your post #205 before you accuse someone else of having a misunderstanding about a concept.

Here's my post 205:

Stated in a simplified way, the reaction force of a floor when another floor falls on it is not necessarily equal to the force the other floor exerts on it. IF it is equal THEN the falling floor will stop. When the maximum reaction force the floor can exert is exceeded (the connections break), that now detached floor will accelerate, due to the force of the upper floor and gravity.

Magnitudes matter. And Cole makes mistakes with magnitudes due to scaling issues and maybe others.

I stand by what I said. Your misconception of what objects the pairs of forces apply to keeps misguiding you.

 

[sts60]

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

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.

I have no use for anyone who would gloat over someone admitting a mistake in a discussion about physics or engineering. I haven't followed the part of the discussion you're talking about, but you deserve to be commended, not ridiculed, for acknowledging an error. Otherwise, how can one learn anything?

Now, about the toy problem of a brick falling through a tissue - do you still think the brick decelerates (slows down) when it goes through the tissue? I'd like to know what you think about that before returning to the problem of how you validate the application of "basic knowledge" to a complex problem.

 

[pgimeno]

Here's a challenge. Please provide a link to an experiment, anywhere, that duplicates the motions observed during the collapse of WTC1 and WTC2.

What's the point? I did that and you ignored it.

 

[FalseFlag]

Deceleration always means a reduction in velocity. Always.

This is correct, because the definition of deceleration is:

Deceleration is the opposite of acceleration. It is the rate at which an object slows down

We can also say that if something is slowing down its velocity is decreasing. If velocity is decreasing with respect to time it is decelerating.

If a large massive object is accelerating (say downward due to gravity), and collides with another object, that collision might alter the total acceleration, perhaps even reducing it (making the magnitude of the acceleration smaller).

"Might" is not the correct word. The acceleration will be reduced. Newton's third law of motion says it has to be reduced.

At the instant of collision, the velocity will change. It has to. If an object is moving in one direction, and it encounters a force in the opposite direction of its motion - even for an instant, it's velocity will change. In fact, its velocity will be less than it was before the impact, if the force is in the opposite direction. Newton's third law of motion says this has to be true.

The definition of acceleration is change in velocity with respect to time. If the velocity changes, even for an instant, then the acceleration must also change, even if it's just for an instant.

The collision does alter the acceleration. The collision provides a force in the opposite direction of travel. A force in the opposite direction of travel will reduce the velocity of the falling object, even if it's just for an instant. If the velocity of an object is reduced with respect to time, then the object is said to decelerate.

But, there will be no deceleration, unless the total acceleration is reduced to the point where it changes sign (and thus, has to go through a "zero").

This is wrong.

Let me break this down concept by concept.

1. If an object is in motion it has a velocity. Velocity is the speed of the motion and direction of motion.
2. Acceleration is a change in velocity with respect to time.
3. If the velocity is increasing with respect to time it is said to accelerate.
4. If the velocity is decreasing with respect to time it is said to decelerate.

Let me summarize this.

If velocity increases with respect to time there is acceleration.
If the velocity stays constant with respect to time there is no acceleration.
If the velocity decreases with respect to time there is deceleration.

Are any of the above statements incorrect? No.

Now, let's break down your statement to show why it's wrong.

But, there will be no deceleration

This is wrong because in your example an object is accelerating downwards. To be perfectly clear, this means that the velocity is increasing in the downwards direction with respect to time. In your example the accelerating object then collides with another object.

, unless the total acceleration is reduced to the point where it changes sign (and thus, has to go through a "zero").

This is wrong. Newton's third law says that for every action there is an equal and opposite reaction. If your example object is accelerating downwards, at the instant of impact with the other object the velocity will change. It has to, because it is encountering a force in the opposite direction of travel. The opposite force causes the velocity to decrease. What term do we use when the velocity of an object decreases with respect to time? The term is deceleration.

If there is deceleration, and Newton has have proven there is, your statement is wrong.

If there is deceleration, the massive object will slow down. If the deceleration is sufficient, the object might even slow down to a stop, and eventually reverse its direction of motion.

The above statement is correct.

You fail to grasp this bit of elementary physics.

No, I don't. I just corrected you. If you want to be taken seriously, admit you were wrong and move on.

 

[FalseFlag]

What's the point? I did that and you ignored it.

Refresh my memory and repost the link that completes the challenge.

 

[FalseFlag]

First of all, in a lot of cases the opposing forces will definitely NOT be equal. For instance, if you punch a piece of paper, it will most definitely NOT exert an equal opposite force, and will break, tear or buckle.

No.

Your post shows that you have a gross concept error. Newton's third law of motion says that for every action there is an equal and opposite reaction.

Your example proves you do not understand this.

Yes, if you punch a piece of paper the paper will exert an equal and opposite force on your fist. That fact that the paper does not stop your fist has nothing to do with Newton's third law.

You need to understand this before you keep claiming I am the one who does not understand.

 

[sts60]

...At the instant of collision, the velocity will change. It has to. If an object is moving in one direction, and it encounters a force in the opposite direction of its motion - even for an instant, it's velocity will change. In fact, its velocity will be less than it was before the impact, if the force is in the opposite direction. Newton's third law of motion says this has to be true...

The collision does alter the acceleration. The collision provides a force in the opposite direction of travel. A force in the opposite direction of travel will reduce the velocity of the falling object, even if it's just for an instant. If the velocity of an object is reduced with respect to time, then the object is said to decelerate....

This is only true if the net force on the object is opposed to the direction of travel. In the brick-through-tissue example, for instance, that does not happen because the small force imparted by the tissue is (much) smaller in magnitude than the weight of the brick (i.e., the gravitational force on the brick). In that case, the velocity of the brick is never reduced; in fact, it continues to accelerate (speed up) during the impact, just not as much before and after.