The physics toolkit

[Carll68]

No, I have provided a range of values. I have told you why the amplification factor of *2* is not a constant. I've provided you with all manner of reasons why. It's ridiculous.


1/1.76 is a reasonable bottom-end estimate, as I've already told you. Could be even larger, even approaching 1*Fo. The answer is anywhere inbetween that and > 1/2. It is most definitely NOT exactly 1/2, as any real-world system with an amplification factor of exactly 2 is physically unreasonable.

A reminder...
[qimg]http://femr2.ucoz.com/_ph/1/440820712.png[/qimg]
Read it again, and TRY and understand.


Gave you the answer over a year ago. That you cannot comprehend that your cut and paste answer makes assumptions and provides a theoretical answer, not a real-world one, is your problem. Many examples in physics make assumptions about the real-world. Your quoted example is one of them. There's nothing wrong with that as such, until you say that a more correct answer which does take account of assumptions is wrong.


No. That is the one answer which is WRONG. It's a reasonable approximation.

I'll try one last time to help you see the *real-world*...

1) The question does not state the medium the experiment is conducted within. Correct ?

2) So the answer you say is correct should be the same whether it's done in air, or in treacle. Correct ?

3) The question does not state by how much the elastic string stretches before it breaks. Correct ?

4) So the answer you say is correct should be the same whether the string stretches by 1mm or 1 mile. Correct ?

5) If you drop a weight in air it falls at a different rate than it would in treacle. Correct ?

6) The surface area of the weight dropped in the treacle has an effect on it's drop rate when it's mass is taken into account. So the drag coefficient will affect it's drop rate. Correct ?

7) The time it takes for the elastic thread to break is not stated. Correct ?

8) How much the elastic thread stretches by before breaking, what medium the experiment is conducted within and the drag coefficient of the applied mass will all affect the time it takes for the elastic thread to break. Correct ?

Etc.

Do you understand the implications of the text in the included image ?

Specifically why (1+e^-ζπ) is relevant in this context ?

"In practice damping is rarely included in calculations of this sort"

Tell you what. Ask some of the local physics bods. Let me know how you get on.

You are truly clueless,

you have failed to answer the question correctlly time and time again.

The question is what the question is. Anyone who truly understands physics beyond youtube and investigoogling can answer (and has answered---This problem has been solved correctly (13/9/05) by Qiu Shi Wang and Ying Cun Luo, freshmen at Peking University, China , and (13/9/05) by Chetan Mandayam Nayakar, a student at India Institute of Technology, Madras, India ) the question with ONLY the information given in the question.. just as you would on an exam.

IT IS THE ONLY INFORMATION YOU NEED.

You screaming "I need more info" only showcases your inability to understand physics to one and all who visit this thread.

You have failed. You are 100% incorrect in your answer. It is and always will be::: The thread will break if F=Fo/2

Never changes. But you don't get it. just like the object entering the tunnel, just like the conservation of momentum...you don't get it, you answered wrong..and you dance.

I am laughing at this dialog, just as others are. You FAILED. You answered WRONG. You continue to ANSWER INCORRECTLY. You pollute this forum with a dirth of uneducated nonsense, but you are too blind to see your own failures.

You have shown no work to validate your inane dime store physics nonsense...and you never will. You have only presented vapid excuses as to why you can not show your work. Your insipid nonsense would be hilarious was it not so pathetic.

My advice to you is to admit you are wrong, invest in an actual education, and get on with your life.

 

[Carll68]

It is very telling that instead of answering an SAT physics question, you have taken time to question why the question is presented.

Professor "We want to test your 1st grade math skills. So, tell me, what is 1+1, "
Student FEMR "why did you choose to ask me that question?"
Professor "i just told you why"
Student FEMR "Sorry, I can not answer until you tell me why I have to, and everyone else knows my answer will be correct, so there truly is no need"

Pathetic.

 

[TexasJack]

Wrong..look how the uneducated Charlatan wiggles and squirms to hide his tender underbelly. The question he assumes I asked was never asked by me..yet indeed it was asked by someone else..I pointed this out, and hilarity ensued.

In fact, as it was pointed out, the correct answer to the question he pretended I asked was and is *0.5 ... yet he answered 1/1.76 http://www.internationalskeptics.com/forums/showthread.php?postid=5971926#post5971926 on this very forum. Doesn't get more uneducated than that folks.

Kid doesn't even have a clue when he exposes himself. http://www.internationalskeptics.com/forums/showthread.php?postid=5977115#post5977115

Copy of his failed answer to the question http://www.internationalskeptics.com/forums/showthread.php?postid=5979148#post5979148 and the ensuing argument between him and "bigc0282"..notice how he does not even grasp what 'bigc0282' is saying.....then, without proof, states i am 'bigc0282'

http://www.internationalskeptics.com/forums/showthread.php?postid=5979877#post5979877 further evidence of his insane uneducated delusions

Wow, I remember these now. The conservation of momentum ordeal, that was comedy gold. I also love the his "friend" ACgravity. Priceless!

 

[Carll68]

Here--I will dumb this down for you.

Given what is stated in the question (The question was:A weight is hanging on an elastic thread. An additional stretching force F is applied and is gradually (slowly) increased. When the force reaches value Fo the thread breaks. What should be the minimal size of a force that breaks the thread, if such a force is applied instantaneously and remains unchanged.)will the thread break if F=Fo/2?

Yes, or No?

Will it break every time, given what is stated in the question, if F=Fo/2?

Yes, or no?

Will it break every time, given what is stated in the question, if F=1/1.76?

Yes, or No?

 

[femr2]

Here--I will dumb this down for you.

Given what is stated in the question (The question was:A weight is hanging on an elastic thread. An additional stretching force F is applied and is gradually (slowly) increased. When the force reaches value Fo the thread breaks. What should be the minimal size of a force that breaks the thread, if such a force is applied instantaneously and remains unchanged.)will the thread break if F=Fo/2?

Yes, or No?

Unlikely. Can't think of a system which would be physically reasonable to result in instantaneous load amplification of exactly 2. All manner of other factors and properties of the thread and environment may come into play.

Will it break every time, given what is stated in the question, if F=Fo/2?

Yes, or no?

No.

Will it break every time, given what is stated in the question, if F=1/1.76?

Yes, or No?

You've misquoted. You should have written F=1/1.76*Fo.

No.

It's what the question doesn't state that is the problem.

There is a world of difference between theoretical physics and applied physics. I learned that lesson well with my misunderstanding on the CoM energy transfers. Think of the problems of perfectly rigid bodies and perfectly inelastic collisions, both of which are used regularly in physics *problems*, but neither of which can actually exist in the real world.

I've requested this ridiculous dialogue be split by mods into it's own thread. I'm not sure if they'll oblige, but would appreciate other members also requesting the split.

 

[newton3376]

Given what is stated in the question (The question was:A weight is hanging on an elastic thread. An additional stretching force F is applied and is gradually (slowly) increased. When the force reaches value Fo the thread breaks. What should be the minimal size of a force that breaks the thread, if such a force is applied instantaneously and remains unchanged.)will the thread break if F=Fo/2?

A few questions about this problem....

When you say "if such a force is applied instantaneously and remains unchanged" what do you mean?

Are you saying that you apply an "instantaneous" force and then continue applying the force?

Or are you saying that you apply the "additional force" instantaneously and allow the string+weight to undergo oscillitations due to this "impulse force" that you applied over some short time period?

I'm unclear as to what the wording is implying....are you continuing to apply the "additional force" or is it a short lived force that simply creates oscillations?

 

[Carll68]

A few questions about this problem....

When you say "if such a force is applied instantaneously and remains unchanged" what do you mean?

Are you saying that you apply an "instantaneous" force and then continue applying the force?[QOUTE]

Hi, .."yes" is the answer to your question as far as I can tell..but, mind you, I am not a self proclaimed 'physics expert' like FEMR. One would think that if freshmen in college can answer this question, a 'physics expert' such as FEMR could as well. Not the case, however. I do want to thank yous for asking and actually inquiring as to the solution as opposed to FEMR's lame uneducated attempt at backtracking and dancing, defending his incorrect answer.. Here is the actual answer and solution to the question:


The answer: The thread will break if F=Fo/2.

The solution:
Before the force is applied the weight of the object hanging on the thread is balanced by the tension force of the thread. Once the additional force F is applied downwards the TOTAL force becomes F, and the weight starts executing harmonic oscillation under the influence of the forces. It starts the oscillation at the top point of the period. After a quarter of the period it reaches the midpoint of the oscillation at which the total force vanishes. After half of the period it reaches the bottom point of the oscillation, at which, by symmetry, the total force is F UPWARDS. This total force is result of the applied external force F pointing downwards, and the increase in the thread tension, which must be 2F and point upwards. Thus, the maximal thread tension is TWICE larger than the applied force. Consequently, F=Fo/2 suffices to break the thread.

I hope this pops the eyes of those who gave even an ounce of credibility to FEMR.

 

[Carll68]

Gee, never would have guessed that you would answer the initial question incorrectly, then fail to see your error, then run like a coward from your error, defending your error, then not defending your answer when asked..then ignoring another SAT question, then ultimately just ignore the entire thing.

Face it fraud, your ability to understand even rudimentary physics is sorely lacking.

Your answer is and always will be 100% wrong. Everyone here can see you are a Charlatan. Then, you don't even know why your answer is wrong, and try to blame it not on your own ability (or lack there of) - but on the lack of superfluous fluff that is not in the question because it is not needed.

I am beyond words at the insipid idiocy you have presented here for all to see. Each one of your posts debunks your prior one. You have run from the tunnel question as if it was the plague, after asking me to present it weeks ago. You can not answer it just like you could not correctly answer BigC0282's question.

Please, I implore you, invest in a substantial education.

 

[Dog Town]

I've made my position repeatedly clear. There are serious issues with the accepted initiation sequences, and I am using whatever means at my disposal to investigate.

I think you meant to say investigoogle. I could be wrong. You should learn to say my previous sentence. You would only be investigating this minutia, if you had some theory, that these minor issues point to something else (cue spooky music). Perhaps you want to help re-write a building code, or two. Is that it? Nah...

Fun to watch, though.

 

[femr2]

Your answer is and always will be 100% wrong.

Nope.

you don't even know why your answer is wrong, and try to blame it not on your own ability (or lack there of) - but on the lack of superfluous fluff that is not in the question because it is not needed.

Again, there is your problem.

What you term *superfluous fluff* is critical to answering the question.

Physics questions regularly include entities which cannot actually exist in order to simplify an answer, and regularly present limiting case results.

The *2* in your textbook answer is a theoretical limiting case.

In reality there's the possibility of approaching *2* (possibly even infinitely close to), but not reaching exactly *2*.

 

[newton3376]

Hi, .."yes" is the answer to your question as far as I can tell..but, mind you, I am not a self proclaimed 'physics expert' like FEMR.

I would assume "yes" is the answer since if you just applied the force and let go then I would expect some kind of a damped oscillation for the thread...this would seem to be a classic problem like one would encounter in differential equations....simply a mass and thread that gets stretched and then oscillates.

One would think that if freshmen in college can answer this question, a 'physics expert' such as FEMR could as well. Not the case, however.

This is one area where I think debunkers are often just as guilty as truthers in overstating something.....from my experience I can tell you that most freshman in college would not be able to answer this question without some effort, if they could answer it at all.

I do want to thank yous for asking and actually inquiring as to the solution as opposed to FEMR's lame uneducated attempt at backtracking and dancing, defending his incorrect answer.. Here is the actual answer and solution to the question:

I have read it several times.....but the explanation to me seems overly simplistic and seems a bit unclear as well.

The answer: The thread will break if F=Fo/2.

I'm willing to accept that this is the answer.....but I'm not clearly seeing it.

Let me break down the solution so maybe someone can correct any errors I am making....

The solution:
Before the force is applied the weight of the object hanging on the thread is balanced by the tension force of the thread.

So far so good....net force is zero....got it.

Once the additional force F is applied downwards the TOTAL force becomes F, and the weight starts executing harmonic oscillation under the influence of the forces.

I understand that the total force is "F" while the force is applied.....but the second part confuses me a bit....

Are you saying the harmonic oscillations occur while you continue to apply "F"? So then we have harmonic oscillations occuring while we continue to stretch the string, right?

Isn't the continually applied force "F" a "forcing function"?

Isn't this a situation of a classic nonhomogeneous differential equation?

It starts the oscillation at the top point of the period. After a quarter of the period it reaches the midpoint of the oscillation at which the total force vanishes.

How does the total force vanish is we are continually applying "F"?

After half of the period it reaches the bottom point of the oscillation, at which, by symmetry, the total force is F UPWARDS.

Are you saying the total force is "F" upwards because of the oscillations or because you are still applying "F"?

This total force is result of the applied external force F pointing downwards, and the increase in the thread tension, which must be 2F and point upwards. Thus, the maximal thread tension is TWICE larger than the applied force. Consequently, F=Fo/2 suffices to break the thread.

Maybe I'm forgetting my basic physics or misapplying what I remember from differential equations....I haven't done this stuff in a few years, but it seems to me you would need to set up the differential equation and solve for the specifics before you can say "Fo/2" breaks the thread.

What kind of a force is "F"? Is it sinusoidal? Is it constant?

I hope this pops the eyes of those who gave even an ounce of credibility to FEMR.

I'm still trying to grasp the physics question....

 

[Carll68]

When I state 'freshman in college'..it is not a generality. Newton, if you review my prior posts, you will see that of the people that answered this question correctly, two were, indeed, freshman in college.

"(1/06) This problem has been solved correctly (13/9/05) by Qiu Shi Wang and Ying Cun Luo, freshmen at Peking University, China , and (13/9/05) by Chetan Mandayam Nayakar, a student at India Institute of Technology, Madras, India . "

Also Newton, please note the following:

Comment: This problem has been taken from an old issue of the journal "Kvant" ("Quantum") (Problem F1209, the issue of 1990). Copies of the old issues of that journal can still be found (in Russian) on the web. It is probably the best Physics-Mathematics journal for high-school children (as well as university students).

The simple fact is this: The question can and has been answered with only the information supplied in the question. No further information is needed.The answer is that the thread will break if F=Fo/2, and the reasons why are given in the solution. The fact that the uneducated Charlatan FEMR has not only answered this question wrong, but continues to defend his wrong answer via superfluous fluff that he feels needs to be presented in the question, which indeed has no use, is clear and undeniable proof of his complete ignorance on high school level physics. This is not advanced stuff here....like the collapsing of a steel tube in tube structure after being impacted by the extreme KE off a commercial airliner full of fuel and left to burn.

Think Shyman Sunder could answer this question?

If this fraud can't answer a simple high school question correct, why should anyone invest a second into his uneducated theories onc ollapse?

Bottom line is his answer is wrong.

On a test it would be wrong. He would fail.

Pretty simple question for a self proclaimed 'physics expert' to get incorrect, no?

Oh, and FEMR, how are you coming with the 'tunnel' question fraud? One would think an expert like you would have solved this by now.......

 

[femr2]

I'm willing to accept that this is the answer

I have tried to explain to Carll why Fo/2 is an (unattainable) limiting case, and provided many factors which affect the real-world outcome.

The *answer* he is quoting assumes zero energy dissipation, dimensionless components and massless components (among many others).

Clearly the result will differ if the experiment is conducted within a vacuum with spherical masses and incredibly thin almost inelastic thread to a similar experiment performed in treacle using cube masses and incredibly fat very elastic thread.

Consider the effect of the stretching phase of the thread within the treacle taking a long time, and consider the practical difference between that and applying the full initial force Fo slowly. The *answer* will tend towards 1*Fo.

Can't forget about time of course. Even *instantaneous* is a no-go.

A range between 1/1.76*Fo and 1/2*Fo is fairly reasonable using the damping ratio for rubber in (1+e^-ζπ).

Could argue about the low-bound value (1.76), but *2* in the real world is not achievable in any system definition I am aware of.

 

[Carll68]

The only thing clear here is that you have not a clue about what you are saying. I knew this all along, now it is clear for those educated enough to see this.

The answer is, was, and always will be F=Fo/2

You added inept and uneducated fluff, but this does not change that F=Fo/2

Anyone who is reading this and understand physics knows that the answer is F=Fo/2

They can see you are wrong, and to uneducated to know why you are wrong. People who do not know, can look up the Journal Kvant, http://kvant.mirror1.mccme.ru/1990/05/resheniya_zadach_f1206_-_f1212.htm (it is Russian, question 1209 page 31 but the math is universal...F=Fo/2 or simply google the question.

So, now you are arguing not just against me, but against the rest of the educated world.

Bravo!

 

[Carll68]

I have tried to explain to Carll why Fo/2 is an (unattainable) limiting case, and provided many factors which affect the real-world outcome.

Could argue about the low-bound value (1.76), but *2* in the real world is not achievable in any system definition I am aware of.

Talk about a self debunk kid!!! Originally, when you were laughed out of the comment section for your incorrect answer, you tried to back in that the answer was F=Fo/2...do you have short or long term memory issues?

 

[femr2]

Talk about a self debunk kid!!! Originally, when you were laughed out of the comment section for your incorrect answer, you tried to back in that the answer was F=Fo/2...do you have short or long term memory issues?

My final post to you. It's an utter waste of time, and am sure the mods will split this dialogue out if only to minimise your inevitable embarrassment.

My original answer to you (over a year ago when you were indeed posting on YT under the sock blgc028282) included the range appropriate for the damping ratio of rubber (elastic thread) and the continual affirmation that *2* was not attainable. The entire *discussion* is there for posterity, as is this one. There's really nothing more to say on the subject.

It is clear that your understanding runs only as deep as the quote you have spammed this thread with, and that you have no interest in progressing your understanding.

 

[W.D.Clinger]

I've requested this ridiculous dialogue be split by mods into it's own thread. I'm not sure if they'll oblige, but would appreciate other members also requesting the split.

Seconded.

The question in the original post was more mathematical than physical, and the thread has become even more interdisciplinary with time. If physicists were the only people qualified to post in this thread, then femr2, Carll68, and I would not be the only ones who aren't qualified.

This is one area where I think debunkers are often just as guilty as truthers in overstating something.....from my experience I can tell you that most freshman in college would not be able to answer this question without some effort, if they could answer it at all.

Agreed.

 

[newton3376]

When I state 'freshman in college'..it is not a generality. Newton, if you review my prior posts, you will see that of the people that answered this question correctly, two were, indeed, freshman in college.

But when you use that phrase over and over combined with implying that this is "High School" level physics you seem to be generalizing....

"(1/06) This problem has been solved correctly (13/9/05) by Qiu Shi Wang and Ying Cun Luo, freshmen at Peking University, China , and (13/9/05) by Chetan Mandayam Nayakar, a student at India Institute of Technology, Madras, India . "

Also Newton, please note the following:

Comment: This problem has been taken from an old issue of the journal "Kvant" ("Quantum") (Problem F1209, the issue of 1990). Copies of the old issues of that journal can still be found (in Russian) on the web. It is probably the best Physics-Mathematics journal for high-school children (as well as university students).

Yes I have googled this question looking for the original source and looking for some better explanations.....plus you have mentioned this several times. I'm aware its from the journal "Kvant".

The simple fact is this: The question can and has been answered with only the information supplied in the question. No further information is needed.The answer is that the thread will break if F=Fo/2, and the reasons why are given in the solution. The fact that the uneducated Charlatan FEMR has not only answered this question wrong, but continues to defend his wrong answer via superfluous fluff that he feels needs to be presented in the question, which indeed has no use, is clear and undeniable proof of his complete ignorance on high school level physics. This is not advanced stuff here....like the collapsing of a steel tube in tube structure after being impacted by the extreme KE off a commercial airliner full of fuel and left to burn.

If it's so easy then can you give me a better explanation or a more detailed one? I asked a few specific questions about the problem setup in an earlier post, so any help you can give me in understanding the answer would be appreciated.

Think Shyman Sunder could answer this question?

Yes.

If this fraud can't answer a simple high school question correct, why should anyone invest a second into his uneducated theories onc ollapse?

Well I am an Electrical Engineer with several years of experience and I was a math, physics, and engineering tutor in college and continue tutoring both high school and college students to this day and I'm not sure I fully understand the justification given in the answer.

This is not a "simple High School" question.

Bottom line is his answer is wrong.

On a test it would be wrong. He would fail.

I'm willing to agree that "F=Fo/2" is the correct answer....I just don't fully understand the explanation. It seems overly simplistic and lacks the detail that we would have if we set up and solved a Differential Equation for the problem....but I think we would need the details of "F" to do so....

Pretty simple question for a self proclaimed 'physics expert' to get incorrect, no?

I'm not convinced it is simple....I mean maybe it is and I am simply not seeing it or having a moment of stupidity here....so help me out with the explanation....

 

[newton3376]

I have tried to explain to Carll why Fo/2 is an (unattainable) limiting case, and provided many factors which affect the real-world outcome.

The *answer* he is quoting assumes zero energy dissipation, dimensionless components and massless components (among many others).

Clearly the result will differ if the experiment is conducted within a vacuum with spherical masses and incredibly thin almost inelastic thread to a similar experiment performed in treacle using cube masses and incredibly fat very elastic thread.

Consider the effect of the stretching phase of the thread within the treacle taking a long time, and consider the practical difference between that and applying the full initial force Fo slowly. The *answer* will tend towards 1*Fo.

Can't forget about time of course. Even *instantaneous* is a no-go.

A range between 1/1.76*Fo and 1/2*Fo is fairly reasonable using the damping ratio for rubber in (1+e^-ζπ).

Could argue about the low-bound value (1.76), but *2* in the real world is not achievable in any system definition I am aware of.

Can you explain the answer to me then? I asked a few questions in an earlier post about the details of "F" and the differential equation....

 

[newton3376]

The only thing clear here is that you have not a clue about what you are saying. I knew this all along, now it is clear for those educated enough to see this.

The answer is, was, and always will be F=Fo/2

You added inept and uneducated fluff, but this does not change that F=Fo/2

Anyone who is reading this and understand physics knows that the answer is F=Fo/2

They can see you are wrong, and to uneducated to know why you are wrong. People who do not know, can look up the Journal Kvant, http://kvant.mirror1.mccme.ru/1990/05/resheniya_zadach_f1206_-_f1212.htm (it is Russian, question 1209 page 31 but the math is universal...F=Fo/2 or simply google the question.

So, now you are arguing not just against me, but against the rest of the educated world.

Bravo!

I just looked through the math on that mirror site.....

That seems reasonable although it would be nice to have the translation as well....but I think I see the general reasoning.