Who killed Meredith Kercher? part 23

[bagels]

Vixen are you going to attempt an intellectually honest discussion and tell me what I got wrong in my visual reconstruction, or are you going to spam irrelevant posts deflecting the issue, which is what you believe happened with regards to the glass dispersal in the room from an inside throw?

 

[LondonJohn]

It depends on its weight and the height from which it is dropped, hence, these are factored into the formula.

Drop a heavy object from a tall building together with a light object, and you'll find (Gallileo) the heavy object lands nearer to the point from which it is dropped than the lighter object. this is the stop distance that helps you have a picture of the force of its impact. A lead weight will come down harder than a feather.

You would need calculus for different speeds but there's no harm using short cuts, such as pythagoras theorem or the parallogram, on the principle the direction of the forces can be represented abstractly as equal on their opposite sides.

Oh this is priceless!

Firstly, you've managed to misrepresent Galileo's Theory in pretty much the maximum way possible. That is impressive in and of itself! (Go and read Galileo's Theory and try to understand it).

Secondly, a heavy object dropped from a tall building will fall in exactly the same place (that is, below the point from which it was dropped - which is what I assume you meant by the horribly imprecise and incorrect "nearer to the point from which it is dropped") as a lighter object (and lateral displacement also has ABSOLUTELY ZERO to do with Galileo's Theory....). The only thing that would change this is strong lateral wind*, and in turn the effect of lateral wind would depend both upon the lateral area profile of the object being dropped and the mass of the object (i.e. not merely mass). For example, if a 1kg ball of balsa wood and a 500g ball of lead were both dropped together from a tall building, in the presence of a strong crosswind, the lighter ball of lead would land considerably closer to the point directly below the drop point than the heavier ball of balsa.

The rest of your post is utterly dismissible (your ideas about "stop distance" and "giving a picture of the force of its impact" are beyond cogent analysis, since they are so horribly, horribly wrong, and the whole final paragraph is nothing more than the random throwing in of things you appear to have heard somewhere in relation to algebra, and it both meaningless and wholly invalid (as well as being empirically wrong in several respects).

Very impressive work. If I were you, I'd seriously consider stopping now. This is becoming a comedy sideshow of shockingly inept "physics". Oh well......


* Of course the exception to this rule is where the object in question has a disproportionate surface area in relation to its mass - e.g. a feather, a playing card, or a snowflake. In those sorts of cases, the effects of downward air resistance, even in perfectly calm conditions, will be significant, and when coupled with aerofoil effects and effects caused when the tumbling object presents its main surface area at an angle to the air against which it is moving, will cause the object to move laterally in unpredictable ways (as well as significantly slow down its rate of descent). But those are special cases - and cases which require extremely complex modelling involving the application of chaos theory. For all "regular" objects, Galileo's Theory broadly applies: for example, a 5kg iron ball and a 25kg iron ball, where both are dropped from a tall building, will hit the ground at the same time, directly below the dropping point.

 

[Vixen]

Another unique discussion of physics.

Could you provide some more detail about your first statement? For example, suppose twins, "A" and "B", of the same height, throw a ball to each other. "A" throws the ball underhanded at a height of 1 meter to "B", and "B" catches the ball in her hand at a height of 1 meter. The ball does not touch the ground in its travel between "A" and "B". Could you detail all the forces and velocities, in terms of magnitudes and direction, that are involved in the throwing and travel of this ball? What keeps the ball up in the air?

There will still be some kind of lift, otherwise there won't be much power in the trajectory. Think about it, the hand has to move forward to throw. Even if under arm, if you let the ball go before you have thrust it forward, it'll just roll down to the floor and the twin will tell you to throw it properly, which means a mild upward thrust, ditto with a bat. The only true horizontal velocity is along the ground or along a surface.

NASA has a good tutorial here as to what happens to a baseball in flight, which can be approximated to s burglar throwing a brick, except, the centre of gravity will be radically different.

https://www.grc.nasa.gov/www/k-12/airplane/flteqs.html

 

[Vixen]

Vixen are you going to attempt an intellectually honest discussion and tell me what I got wrong in my visual reconstruction, or are you going to spam irrelevant posts deflecting the issue, which is what you believe happened with regards to the glass dispersal in the room from an inside throw?

Bagels, I cannot see any sign of the shutters in your reconstruction.

 

[Vixen]

Are you sure there are fewer forces acting on a ball being rolled along the ground than one thrown through the air? Care to articulate, precisely, the various forces acting on a ball rolling along the ground vs those acting on a ball being thrown through the air?

(Hint 1: you couldn't be more wrong)

(Hint 2: you have absolutely NO idea what you are talking about in the entire realm of physical forces, the physics of motion and ballistics theory. No idea at all. At all. It's very entertaining though).

No, I am saying it is far easier to calculate!

 

[Numbers]

There will still be some kind of lift, otherwise there won't be much power in the trajectory. Think about it, the hand has to move forward to throw. Even if under arm, if you let the ball go before you have thrust it forward, it'll just roll down to the floor and the twin will tell you to throw it properly, which means a mild upward thrust, ditto with a bat. The only true horizontal velocity is along the ground or along a surface.
NASA has a good tutorial here as to what happens to a baseball in flight, which can be approximated to s burglar throwing a brick, except, the centre of gravity will be radically different.

https://www.grc.nasa.gov/www/k-12/airplane/flteqs.html

Would you be so kind as to provide a reference for your statement that the ball has lift? Could you explain what "some kind of lift" means? Are there different kinds of lift? Can you provide a calculation of the lift, showing its magnitude and direction?

Could you kindly provide a reference for your statement that the only true horizontal velocity is along the ground or a surface? Here are some definitions of "horizontal" that I found online:

1
a : of, relating to, or situated near the horizon b : parallel to, in the plane of, or operating in a plane parallel to the horizon or to a baseline : level <horizontal distance> <a horizontal engine>
Source: https://www.merriam-webster.com/dictionary/horizontal

1Parallel to the plane of the horizon; at right angles to the vertical:
‘a horizontal line’

Source: https://en.oxforddictionaries.com/definition/horizontal

 

[LondonJohn]

Yes, and note where the missile lands. It hits the window/shutter and falls straight downwards, exactly as I predicted.

Note the back fall of glass on the windowsill outside.

Yes. You seem to be unaware that there was a deep (c.50-60cm) exterior stone sill outside Romanelli's window. Which is exactly where one would expect pieces of glass to fall after an impact on the window from a rock thrown from the outside. The exterior sill was easily deep enough in profile to capture the pieces of glass that might have fallen down and slightly backwards after impact.

No pieces of glass of significant (>3mm diameter) size would be expected to have been propelled further rearwards than the depth of the sill. The only pieces of glass that might have been propelled further rearwards than the sill would have been of very small size (<2mm diameter) and very few in number. And the inept police at the scene never even gave themselves a chance of finding that sort of evidence in the ground below Romanelli's window: they conducted nothing more than the most cursory, ineffective search (no fingertip search, no fine sieving of the earth), and furthermore they trampled all over the ground while using it as a cigarette-and-phone-call area. Unbelievable.

The upshot is that it's absolutely possible that there indeed were some very small particles of glass projected back onto the ground under Romanelli's window - consistent with a rock being thrown through Romanelli's window from outside. The incompetence of the police investigation means we will never know, but it also means that it's fundamentally impossible to claim that there never were any such small particles of glass on the ground under Romanelli's window. And that's the be-all-and-end-all of it.

 

[LondonJohn]

Would you be so kind as to provide a reference for your statement that the ball has lift? Could you explain what "some kind of lift" means? Are there different kinds of lift? Can you provide a calculation of the lift, showing its magnitude and direction?

Could you kindly provide a reference for your statement that the only true horizontal velocity is along the ground or a surface? Here are some definitions of "horizontal" that I found online:

1
a : of, relating to, or situated near the horizon b : parallel to, in the plane of, or operating in a plane parallel to the horizon or to a baseline : level <horizontal distance> <a horizontal engine>
Source: https://www.merriam-webster.com/dictionary/horizontal

1Parallel to the plane of the horizon; at right angles to the vertical:
‘a horizontal line’

Source: https://en.oxforddictionaries.com/definition/horizontal

Seriously: the gibberish "physics" being displayed in Vixen's "arguments" today is beyond parody, beyond analysis and almost beyond comprehension. I think asking for clarity or answers (other than purely rhetorically) is an exercise in futility.

If somebody who actually has even a high-school understanding of the physics of motion and ballistics would like to come here to post an argument about how/why a young, fit, adult male could not have thrown a 4.5kg rock some 2.5m to a window that was horizontally level with the point of the throw, with enough accuracy and force to cause the rock to strike the window and break it, then I'd be happy to engage properly*. Vixen is, in the strongest possible terms, not that person.


* Of course the determining factor here is that anyone who DOES have even a high-school understanding of the physics of motion and ballistics (together with a basic understanding of human physiology and throwing forces) would know very well that of course it's easy for a young, fit, adult male to make that throw, and thus would never be able to construct an argument against the concept. But anyhow...........

 

[LondonJohn]

No, I am saying it is far easier to calculate!

No. No you are NOT saying that.

You said this:

"Horizontal velocity is taken to be something moving along the ground, with fewer forces than something flying through the air."

Are you now stating that you were wrong to write the words "with fewer forces"? Oh dear.

And, for your information, it's significantly more difficult to calculate the forces acting on a ball rolling along the ground than to calculate those acting on a ball flying through the air (in direct contrast to your revised claim). But you wouldn't know or understand that, would you.....?

 

[LondonJohn]

There will still be some kind of lift, otherwise there won't be much power in the trajectory. Think about it, the hand has to move forward to throw. Even if under arm, if you let the ball go before you have thrust it forward, it'll just roll down to the floor and the twin will tell you to throw it properly, which means a mild upward thrust, ditto with a bat. The only true horizontal velocity is along the ground or along a surface.
NASA has a good tutorial here as to what happens to a baseball in flight, which can be approximated to s burglar throwing a brick, except, the centre of gravity will be radically different.
https://www.grc.nasa.gov/www/k-12/airplane/flteqs.html

All of these are stunningly wrong. As is the entire overall tenor of the argument.

I am now becoming convinced that this is all a deliberate attempt at some sort of satirical literary device, with gross stupidity being knowingly employed in order to draw a response. After all, I'm genuinely running out or reasons to believe that these could be serious posts making genuine attempts to employ motion/ballistics physics. Never seen anything quite like it in my life - especially when coupled with the hubris-filled belief in being correct. Amazing! Entertaining, but amazing!

 

[Vixen]

Seriously: the gibberish "physics" being displayed in Vixen's "arguments" today is beyond parody, beyond analysis and almost beyond comprehension. I think asking for clarity or answers (other than purely rhetorically) is an exercise in futility.

If somebody who actually has even a high-school understanding of the physics of motion and ballistics would like to come here to post an argument about how/why a young, fit, adult male could not have thrown a 4.5kg rock some 2.5m to a window that was horizontally level with the point of the throw, with enough accuracy and force to cause the rock to strike the window and break it, then I'd be happy to engage properly*. Vixen is, in the strongest possible terms, not that person.


* Of course the determining factor here is that anyone who DOES have even a high-school understanding of the physics of motion and ballistics (together with a basic understanding of human physiology and throwing forces) would know very well that of course it's easy for a young, fit, adult male to make that throw, and thus would never be able to construct an argument against the concept. But anyhow...........

No, he would not have been horizontally level with the window. The window sill was 12'4" from the ground. Let's say the drop down to the ground was circa five feet, then Rudy being 5'10, so definitely an upward trajectory.

In any case, you are woefully ignorant of physics. You have already been told it is not horizontal velocity. However, here is an animation to help illustrate it clearly for you.


http://www.physicsclassroom.com/mmedia/vectors/hlp.cfm

Many would insist that there is a horizontal force acting upon the cannonball since it is moving horizontally. Yet this is simply not the case. The horizontal motion of the cannonball is the result of its own inertia.

 

[LondonJohn]

No, he would not have been horizontally level with the window. The window sill was 12'4" from the ground. Let's say the drop down to the ground was circa five feet, then Rudy being 5'10, so definitely an upward trajectory.

In any case, you are woefully ignorant of physics. You have already been told it is not horizontal velocity. However, here is an animation to help illustrate it clearly for you.


http://www.physicsclassroom.com/mmedia/vectors/hlp.cfm

Hmmm. What if Guede.......... THREW THE ROCK WHILE STANDING AT THE EDGE OF THE PARAPET?

And I know more about physics than you will ever forget. Of that I am absolutely, unequivocally certain. But that was worth another chuckle - well done!

 

[Numbers]

All of these are stunningly wrong. As is the entire overall tenor of the argument.

I am now becoming convinced that this is all a deliberate attempt at some sort of satirical literary device, with gross stupidity being knowingly employed in order to draw a response. After all, I'm genuinely running out or reasons to believe that these could be serious posts making genuine attempts to employ motion/ballistics physics. Never seen anything quite like it in my life - especially when coupled with the hubris-filled belief in being correct. Amazing! Entertaining, but amazing!

LJ,

I think we may be misunderstanding Vixen's posts on physics. I suspect Vixen obtained the information in these posts from some reference text that we have not been exposed to. Maybe it's next to the one on Italian law in some library for the PGP.

But really, I think these PGP physics posts potentially dangerous - I wouldn't want to be drinking hot coffee while reading one.

I am somehow incredibly amused and delighted by imagining someone lecturing to a meeting of some branch of the American Physical Society or its British equivalent with the content of these PGP physics posts as the subject.

 

[Vixen]

Would you be so kind as to provide a reference for your statement that the ball has lift? Could you explain what "some kind of lift" means? Are there different kinds of lift? Can you provide a calculation of the lift, showing its magnitude and direction?

Could you kindly provide a reference for your statement that the only true horizontal velocity is along the ground or a surface? Here are some definitions of "horizontal" that I found online:

1
a : of, relating to, or situated near the horizon b : parallel to, in the plane of, or operating in a plane parallel to the horizon or to a baseline : level <horizontal distance> <a horizontal engine>
Source: https://www.merriam-webster.com/dictionary/horizontal

1Parallel to the plane of the horizon; at right angles to the vertical:
‘a horizontal line’

Source: https://en.oxforddictionaries.com/definition/horizontal

Horizontal velocity as referred to in calculating vectors is not the same meaning as the colloquial use of the term 'horizontal'. It is specific jargon to differentiate velocity of a different sort.

Do have a look at this webpage that explains the principles in straighforward terms:

http://www.physicsclassroom.com/class/vectors/Lesson-2/Characteristics-of-a-Projectile-s-Trajectory

 

[LondonJohn]

To deal with your woefully inept misunderstanding of the quote you provided:

Many would insist that there is a horizontal force acting upon the cannonball since it is moving horizontally. Yet this is simply not the case. The horizontal motion of the cannonball is the result of its own inertia.

The key word here (which you don't understand) is "force". There is indeed no horizontal force* acting on a cannonball in flight (once it has left the cannon, that is). But that's.....oooh..... 100% different from saying the cannonball has no horizontal velocity in flight (which it most certainly does). Once again, you amusingly articulate your own ignorance while believing you're doing the opposite. Priceless!!!


* Although in strict terms there IS a horizontal force acting on a cannonball in flight: the drag force provided by air resistance as the cannonball moves through the air, acting in the opposite direction to the direction of motion of the cannonball. But clearly this quote was concerned with whether there was a horizontal propulsive force acting on the cannonball in flight - which indeed there is not.

 

[Numbers]

No, he would not have been horizontally level with the window. The window sill was 12'4" from the ground. Let's say the drop down to the ground was circa five feet, then Rudy being 5'10, so definitely an upward trajectory.

In any case, you are woefully ignorant of physics. You have already been told it is not horizontal velocity. However, here is an animation to help illustrate it clearly for you.


http://www.physicsclassroom.com/mmedia/vectors/hlp.cfm

Could you kindly explain to us the differences between a force, an acceleration, a velocity, mass, weight, and inertia?

And here is a paragraph from your citation link; maybe it will help if you wish to converse about physical phenomena:

Many would insist that there is a horizontal force acting upon the cannonball since it is moving horizontally {a cannon firing a cannonball "horizontally" off a cliff is illustrated in the link; the cannonball is shown moving simultaneously sideways and down in the air bordering the cliff face}. Yet this is simply not the case. The horizontal motion of the cannonball is the result of its own inertia. When launched from the cannon, the cannonball already possessed a horizontal motion, and thus will maintain this state of horizontal motion unless acted upon by a horizontal force. An object in motion will continue in motion with the same speed and in the same direction ... (Newton's first law). Remind your self continuously: forces are not required for an object to be moving; once in motion, the presence of forces will only serve to accelerate such objects.

 

[LondonJohn]

LJ,

I think we may be misunderstanding Vixen's posts on physics. I suspect Vixen obtained the information in these posts from some reference text that we have not been exposed to. Maybe it's next to the one on Italian law in some library for the PGP.

But really, I think these PGP physics posts potentially dangerous - I wouldn't want to be drinking hot coffee while reading one.

I am somehow incredibly amused and delighted by imagining someone lecturing to a meeting of some branch of the American Physical Society or its British equivalent with the content of these PGP physics posts as the subject.

The collection of the past two-dozen or so of Vixen's posts could serve as a vivid example of the potent combination of lack of understanding of the most basic concepts of motion & ballistics physics, coupled with a complete inability to recognise that lack of understanding. I actually know a girl from uni who studied particle physics and who now works in research (and has spent a lot of time at CERN in Switzerland), to whom I'm seriously thinking of sending Vixen's collected physics musings as a fun Christmas present

 

[Vixen]

Hmmm. What if Guede.......... THREW THE ROCK WHILE STANDING AT THE EDGE OF THE PARAPET?

And I know more about physics than you will ever forget. Of that I am absolutely, unequivocally certain. But that was worth another chuckle - well done!

Your assumption you know more about physics than me is priceless Herein lies your misconception. If ignorance is bliss, then tis folly to be wise.

Therein lies my error.

 

[Vixen]

To deal with your woefully inept misunderstanding of the quote you provided:

Many would insist that there is a horizontal force acting upon the cannonball since it is moving horizontally. Yet this is simply not the case. The horizontal motion of the cannonball is the result of its own inertia.

The key word here (which you don't understand) is "force". There is indeed no horizontal force* acting on a cannonball in flight (once it has left the cannon, that is). But that's.....oooh..... 100% different from saying the cannonball has no horizontal velocity in flight (which it most certainly does). Once again, you amusingly articulate your own ignorance while believing you're doing the opposite. Priceless!!!


* Although in strict terms there IS a horizontal force acting on a cannonball in flight: the drag force provided by air resistance as the cannonball moves through the air, acting in the opposite direction to the direction of motion of the cannonball. But clearly this quote was concerned with whether there was a horizontal propulsive force acting on the cannonball in flight - which indeed there is not.

You are still not getting it. You still believe that if something is thrown through the air in a straight line it carries on in a straight line..

No, no, no, no no.

 

[Vixen]

Could you kindly explain to us the differences between a force, an acceleration, a velocity, mass, weight, and inertia?

And here is a paragraph from your citation link; maybe it will help if you wish to converse about physical phenomena:

Many would insist that there is a horizontal force acting upon the cannonball since it is moving horizontally {a cannon firing a cannonball "horizontally" off a cliff is illustrated in the link; the cannonball is shown moving simultaneously sideways and down in the air bordering the cliff face}. Yet this is simply not the case. The horizontal motion of the cannonball is the result of its own inertia. When launched from the cannon, the cannonball already possessed a horizontal motion, and thus will maintain this state of horizontal motion unless acted upon by a horizontal force. An object in motion will continue in motion with the same speed and in the same direction ... (Newton's first law). Remind your self continuously: forces are not required for an object to be moving; once in motion, the presence of forces will only serve to accelerate such objects.

Gravity is a force. A trajectory will continue it its path unless there is a force that changes it, or accelerates it. Mass is density and can be measured as weight per cubic feet, inertia is the presence of no forces on an object.

Instead of looking in Merriam-Webster, do look in a physics dictionary as these terms have specific meaning which may vary from their common or garden usage.