Heiwa's bathroom scale experiment

[Heiwa]

They (the loose parts of the lower structure) would have the same mass and would have their own velocity and thus would impact a force on whatever they fall onto. they would be falling with the block but that is not saying they would be attached to it. If one wishes to investigate details though there is one dominent manner by which loose debris within the tower could in effect be said to be "attached" to the intact portion of the falling upper block. Material that breaks loose from a floor pan that does not get bounced outward will be moving slower than the upper block. It is within the perimeter walls and thus will contact the underside of the falling block and thus could be thought of as being "attached" to the upper block as the upper block transfers some of its momentum to speed up the parts trapped under it. If you wish to look at that further it will also indicate a cushioning effect on the upper block by the loose debris which could slow the destruction of the upper block.

Sorry - any loose part of the lower structure cannot have the same mass as the upper block!

Anyway, you suggest that these loose parts, dropping slower, will be trapped under and pushed in front of the upper block while it, the upper block, continues to drop down.

OK, the upper block was never damaged at impact as it became rigid and now pushes loose parts of the lower structure in front of it as a plough.

Questions - how did these parts get loose? And what about the other parts or the lower structure that did not get loose? Did they slow the destruction of the upper block???

Bazant assumes that the upper block is rigid - indestructible. Nothing can stop it.

My children audience is amazed! The know that the upper block has uniform density of 0.18 or that of a bale of wool ... and now it destroys steel columns of a lower structure. They do not believe you. Or Bazant.

 

[Jonnyclueless]

He still thinks the upper block is a single solid piece eh? Guess that explains the pizza boxes.

 

[Heiwa]

Seems that according to your statement a 500 Kg block of concrete somehow has less mass or less momentum than 500 Kg of rocks.

Bazant showed that the force imparted upon the first level impacted after initial failure was, IIRC, 30 times greater than the ability of the floor pan/truss system to resist it. This is due to the combination of the mass of the upper block and the impact force due to the velocity of the upper block.

No any mass of 500 kgs is the same of another mass of 500 kgs. E.g. 500 kgs of wool.

The upper block had uniform density of a bale of wool. 0.18. And the upper block structure was quite similar - most air!

So where did Bazant show that this fluffy upper block could impart (pass on) a force that was 30 times greater than the floor of the lower structure could resist?

The mass we know! It is the volume of the upper block times 0.18 or 33 000 tonnes. Big mass ... but small density.

The impact force due to velocity of the upper block - what was it? We know the velocity was say 7 - 8 m/s. But as explained in earlier posts - force has nothing to do with velocity. Only change of velocity in time. So what are you, or Bazant, talking about?

So what was the change in velocity of the upper block after impact?

And why is this change in velocity not recorded on any video?

 

[Heiwa]

The falling mass would therefore have an even greater velocity when it impacts the next floor ( the only way for it to have as little as the same velocity it would have to have come to a complete stop as it failed the first level ) and thus Bazant correctly concludes that this level has even less ability to halt the upper block.

So the upper block impacts one floor in the lower structure and ploughs it aside or pushes it in front of it self and has then a greater velocity when impacting the next floor than is also ploughs away.

This is real NWO physics.

What to you mean by this : the only way for it (the falling mass) to have as little as the same velocity it would have to have come to a complete stop as it failed the first level . It does not make any sense to me.

Is it a quote from Bazant?

 

[beachnut]

So the upper block impacts one floor in the lower structure and ploughs it aside or pushes it in front of it self and has then a greater velocity when impacting the next floor than is also ploughs away.

This is real NWO physics.

What to you mean by this : the only way for it (the falling mass) to have as little as the same velocity it would have to have come to a complete stop as it failed the first level . It does not make any sense to me.

Is it a quote from Bazant?

In a model...
The mass does not stop. The lower floor fails instantaneously and continues to the next floor. Physics shows this is the model of what happen. If you use momentum equations you will see this is true and matches the speed of failure very closely. Your fantasy is messing up your physics. The speed of the fall is modulated by the changing mass. But this is a model, the actual failure and fall of the WTC is complicated, but can be modeled easily. Your model is junk!

Since there were zero explosives in the WTC on 9/11, your theory is a lie, false, or pure fantasy. You can't do basic physics without making major errors.

 

[Grizzly Bear]

The upper block had uniform density of a bale of wool. 0.18. And the upper block structure was quite similar - most air!

Whether or not the interior space was "mostly air", the materials used for construction were extremely heavy and had more than enough combined mass in the upper section to destroy a single floor. If the net deceleration that the resistance the floor provides is insufficient to stop the falling mass it continues to fall with the added mass of the newly collapsed floor. This has been explained to you ad nauseum, and I expect that you'll simply handwave this with your absurd entanglement of floors and structure claim...

I know you like to keep your models "simple for kids", but I kindly ask that you offer up mathematical figures that demonstrate from an engineering stand point how your model is valid. Not only does it offer you the opportunity for you to dispell accusations that you're composing an argument from incredulity on a grandeur scale, it also offers you the opportunity for you to demonstrate your credentials as an engineer working in the field.

So where did Bazant show that this fluffy upper block could impart (pass on) a force that was 30 times greater than the floor of the lower structure could resist?

You can start by examining his equations which deal with dynamic loading conditions. As an engineer, you should be extremely familiar with the concept. For example note the difference between a car hitting a wall at 10 miles per hour versus a car hitting a wall at 60 miles per hour; impact forces change with velocity and mass and collisions can result in forces that momentarily far exceed to normal weight of the object, hence a dynamic force, or in the case of the trade centers, dynamic load conditions.

The impact force due to velocity of the upper block - what was it? We know the velocity was say 7 - 8 m/s. But as explained in earlier posts - force has nothing to do with velocity. Only change of velocity in time. So what are you, or Bazant, talking about?

Incorrect. Mass and velocity affect impact forces when dealing with objects in motion. It doesn't require any detailed knowledge in physics to understand this. This same concept is well studied in car crash safety tests for example.

And why is this change in velocity not recorded on any video?

You're not serious? [facepalm]
The very root of that statement is utterly ignorant of the fact that the upper section DID begin to accelerate the moment it began to fall, when the structure in the impact region failed. Please avoid stupid comments like these.

 

[Mobyseven]

The upper block had uniform density of a bale of wool. 0.18. And the upper block structure was quite similar - most air!

Do tell me, did all this air fall in unison with the concrete and steel around it? Or is it possible that including all that air in the calculation of the density of the object impacting the floors of the WTC is more than slightly misleading?

 

[jaydeehess]

Sorry - any loose part of the lower structure cannot have the same mass as the upper block!

My bad, it should read "some mass" not "the same mass"

Anyway, you suggest that these loose parts, dropping slower, will be trapped under and pushed in front of the upper block while it, the upper block, continues to drop down.

OK, the upper block was never damaged at impact as it became rigid and now pushes loose parts of the lower structure in front of it as a plough.

Questions - how did these parts get loose? And what about the other parts or the lower structure that did not get loose? Did they slow the destruction of the upper block???

Yes the snapping of these parts would take some energy from the kinetic energy of the falling mass. Did you really read Bazant?
30 times more available energy than required to fail the floor pan/truss system.

Bazant assumes that the upper block is rigid - indestructible. Nothing can stop it.

Did you read all of my last post. Try again to see if I said something about Bazant's approximations.

 

[jaydeehess]

No any mass of 500 kgs is the same of another mass of 500 kgs. E.g. 500 kgs of wool.

well at least you get this correct, I was really worrying about what school gave yuou a diploma.

The upper block had uniform density of a bale of wool. 0.18. And the upper block structure was quite similar - most air!

So where did Bazant show that this fluffy upper block could impart (pass on) a force that was 30 times greater than the floor of the lower structure could resist?

(note that some fonts did not copy accuratly)bolds mine

This gives the equation mg[h + (P=C)] = P2=2C in which m
= mass of the upper part (of North Tower)= 58106 kg, and g = gravity acceleration. The
solution P = Pdyn yields the following elastically calculated overload ratio due to impact of the upper part:
Pdyn=P0 = 1 + q1 + (2Ch=mg)= 31 (1)
where P0 = mg = design load capacity. In spite of the approximate nature of this analysis,
it is obvious that the elastically calculated forces in columns caused by the vertical impact of
the upper part must have exceeded the load capacity of the lower part by at least an order
of magnitude.

The mass we know! It is the volume of the upper block times 0.18 or 33 000 tonnes. Big mass ... but small density.

What the h. does the density have to do with the impact force?

So what was the change in velocity of the upper block after impact?

And why is this change in velocity not recorded on any video?

The failure of the level was quick and required so little of the kinetic energy of the falling mass to do so that the change in velocity would not be visible to the eye. Too bad no one thought to place a large graduated ruler next to the building so that a high speed video could be taken and such measurments made. Dang Al Qada!

 

[jaydeehess]

Do tell me, did all this air fall in unison with the concrete and steel around it? Or is it possible that including all that air in the calculation of the density of the object impacting the floors of the WTC is more than slightly misleading?

Ya think?

Every building I have ever been in seemed a lot more solid than a bale of wool. Yaeh, average density means so very much to this discussion.

 

[jaydeehess]

So the upper block impacts one floor in the lower structure and ploughs it aside or pushes it in front of it self and has then a greater velocity when impacting the next floor than is also ploughs away.

Actually it is basic high school physics
V=v_o+at
In the first drop the initial velocity is zero
Measuring from that level to the next, unless the mass came to a complete stop as it failed the first level then its velocity as it passes the first failed level is added to the increase due to the acelleration to the next.
What school did you say you went to?

What to you mean by this : the only way for it (the falling mass) to have as little as the same velocity it would have to have come to a complete stop as it failed the first level . It does not make any sense to me.

Is it a quote from Bazant?

No, as I said above, its basic high school physics.
What school did you say you attended?

The only way for the falling mass to have the same velocity when it hits the second level beyond the the initial collapse (that is to say it has failed one level and moved onto the next) would be for that mass to have come to a halt as it failed the first level after initial failure.

 

[jaydeehess]

And why is this change in velocity not recorded on any video?

You're not serious? [facepalm]
The very root of that statement is utterly ignorant of the fact that the upper section DID begin to accelerate the moment it began to fall, when the structure in the impact region failed. Please avoid stupid comments like these. .

Actually he wants to know why the upper block did not slow as it failed the first level. He seems to believe that it had to have slowed significantly enough to be noticable.

In fact the acelleration of the collapse zone is approx 20% less than acelleration due to gravity over the course of the collapse. Obviously then the structure did offer 'resistance' to the falling mass.

 

[Jonnyclueless]

Ah, so now Heiwa thinks each floor is a solid object....

 

[Wolrab]

If I jump on the scale, am I supposed to collapse into myself while the scale remains unscathed?

 

[MRC_Hans]

I read the OP, and assumed it was a joke. Surely Heiwa was not serious about it, ..... or?

Hans

 

[Porkpie Hat]

Ah, so now Heiwa thinks each floor is a solid object....

...with the density of a bale of wool!

His entire argument smells like the south end of a north bound cow.

 

[Giggywig]

I read the OP, and assumed it was a joke. Surely Heiwa was not serious about it, ..... or?

Hans

This is my assumption as well. The alternative is too horrible to contemplate.

 

[Zipster]

Where is Heiwa getting this .18 for the density? And what are the units for this? For all we know, the units could be .18 kg/mm^3.

Quite a nice trick he has going. Leave out the units and claim that it's equivalent to a bundle of wool based on the number alone. There's a reason the engineering world has units...

 

[applecorped]

My children audience is amazed! The know that the upper block has uniform density of 0.18 or that of a bale of wool ... and now it destroys steel columns of a lower structure. They do not believe you. Or Bazant.

Barney amazes children too.

The fact that you can only convince children must tell you something. Stop polluting their minds with this drivel. The last thing the world needs is more people believing this nonsense. You are an irresponsible person to promote this to children as fact.

 

[Heiwa]

What the h. does the density have to do with the impact force?

It is Bazant that introduces uniform density of the upper block in his papers as a requirement (apart from being rigid) for impact, shock wave, crush down (of lower structure) and crush up (of upper block) - all to do with impact forces. But he never calculated it.

So I calculated the uniform density of the upper block and got it to be 0.18. Like wool or cotton. Steel has uniform density 7.82 BTW or 43 times more but it is very little steel in the upper block.

How anything with uniform density 0.18 then can be rigid is another question that Bazant does not answer. He just assumes it.

If you drop anything with uniform density of 0.18 on a bathroom scale, I doubt very much there will be a spike, or so.

If you drop anything with uniform density 0.18 in your water filled bath tub, you will find that it floats (after a little SPLASH).

Reason for this is, i.a., that uniform density of water is 1.

The uniform density of you is probably abt 0.98, i.e. you too float in the water (with nose above water).

If a person with uniform density 0.98 tries the Heiwa Bathroom Scale experiment, the result may be BANG, THUD, SPLASH.

Oh yes, (uniform) density has very much to do with the impact force!

Re velocity - if an upper block (or person) with velocity v applies force F (or mg) on a bath room scale, the bath room scale measures F + a spike due to v. And then the spike disappears, and the scale only measures F. The velocity v is then 0.

Where did the spike go? The energy of the spike was simply absorbed by the scale (or actually the spring inside the scale and what was below the scale).