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# imatfaal

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1. ## [solved... sort of] Trigonometry Problem

Agree completely - I remember watching examiners attempt an ad hoc rationalization of similarly poorly written question; it was all intended to help draw out/highlight proper understanding of the subject etc. Then someone piped up - Was the fact that there was no section c, there were three spelling mistakes, and the diagram was wrongly labelled all part of the same teaching strategy; at that point the staff admitted that everyone thought someone else was checking the questions for basic quality control. Did you see the news piece around 6 months ago about errors in exam revision texts?

3. ## Maffs, natural gift or developed skill?

The popular press do like to lionize (or sometimes demonize) those that are extraordinary - this means you will very rarely get a balanced and honest view of those in the public eye. This combined with the fact that in the recent past people like to down play their own talents and work ("I was just lucky..." "It happend that I was the guy on the spot..." "Really it was a team victory" etc. ) means that both the natural ability and the hours of grind are hidden. I have spent time around world class track cyclists and they will talk about the amazing support and coaching, the team morale and c
4. ## In the angular momentum equation, L = r x p, when the magnitude of the radius changes, which one of the remaining variables is correctly conserved ?

! Moderator Note OK Mandlbaur. Last chance to get this thread back on the tracks. Your next post MUST include an equation (with proper naming of symbols) which you believe defines the conservation of angular momentum. FYG $\textbf{L} = \textbf{r} \times \boldsymbol{\rho}$ says nothing about conservation - it merely relates the linear momentum of a particle to the angular momentum of that particle around a specific axis at a perpendicular distance with the magnitude the same as r
5. ## Bullet fired from a gun and a bullet dropped descend simultaneously

Any length contraction is in the direction of motion and can be dealt with in components (if you think in the frame of the pellet then there is no time dilation and all frames must give same answer) - in the y direction / vertical axis the velocity at every moment is similar for the dropped pellet and fired pellet; so no matter how small the relativistic correction might be it would still be the same for both. And for those who quibbled that this post should not be in "Relativity" - surely this is galilean / newtonian relativity? Although forum subtitle does say it is for SR and GR
6. ## [solved... sort of] Trigonometry Problem

@Ruairi I tend to work in radians rather than degrees. The total internal angle of a triangle is pi radians. If you have not covered radians yet then just substitute 180 degrees for Pi and 90 degrees for Pi/2 and it will all make sense. You will also note that you do not need to use a calculator - nor work out any trigonometrical values; all the values needed are given and you can do this with a pencil and paper. It is massively important to learn when you can do this - you are likely to be asked exactly this sort of question in exams in which you are not allowed a calculator! @stu
7. ## Virtual particles and fields

That is my understanding too. I would add that quantum field theory for the other 3 fundamental forces has turned out to be one of the most accurate and explanatory models in human history - so the search for a theory of quantum gravity (and thenceforward unification) is a path worth following. Maybe one of the experts can weigh in on this further question - with the data from experiments such as LIGO, BICEP2, Gravity Probe B etc. has anything cropped up that was a prediction based on solely the existence and current understanding of the graviton from qft rather than based on the underst
8. ## Understanding Reality

You are the one with a comprehension failure - we understand your axiomata; we do not agree them.
9. ## [solved... sort of] Trigonometry Problem

actually upon further inspection (ie sin(alpha+beta) =.08) I realise I made an improper assumption. Correction follows @studiot - I concur with your answers for the angles. Yet I still fail to see how you can solve the upper right hand triangle - you only know one angle and a side; that can create any number of triangles, all with different length y. Could you specify for me how you do this without assuming that the angle between y and h is a right angle?
10. ## Simple probability question

"2) You are a buyer checking a box of apples for % rotten apples. A rotten apple is much more likely to infect neighbours than remote apples." I find this very intriguing. You are right of course, but the upshot is so complicated. A corner apple has only three neighbours which might have been able to turn it rotten - a centre apple has eight etc.; assuming a rectangular array. Assuming different number of generations of infection possible then the odds of a centre apple remaining fresh with a rotten in the box is contrasted with the odds of a corner apple remaining fresh - as the number
11. ## Infinite coin flip probability

QFT is predictive and has been tested to phenomenal precision. String Theory has not once been tested to any level of prediction; basically almost all complex maths will find itself bound up in string theory in some way. Whether string theory turns out to be empirically predictive or theoretically useful in physics, one thing is for certain - it is mathematics and modelling of the highest possible order; perhaps mankind's greatest abstract achievement.
12. ## What is Space made of?

... Excellent post as always Mordred. And because I could never contradict you on physics, I will take this opportunity to take a mild shot at your nomenclature It's Yukawa coupling and Higgs (no apostrophe; named after him not his possessive - which would mean anyway that the apostrophe would be after the s ) Now awaiting the Skitt's Law moment...
13. ## Today I Learned

I have learnt that Forensic no longer means what it used to mean. Forensic means to me "pertaining to the courts of law" and "suitable to being part of the factual pleadings in court" - it seems that through the use of forensic as an adjective in front of words like science and medicine has morphed the meaning such that Forensic now means Forensic Science.* So regarding the discovery magazine article - that may well be the first forensic science but definitely not the first forensic investigation; just off the top of my head Cicero details some forensic investigations (often forensic acco
14. ## Understanding Reality

Agreed. My point was that one form of additional information was a belief (in the mind of L) in the level of credence (in the mind of T) of the words of C; thus one of the "heavy footnotes" would need to be a set of P(x1,x2,...,xn). In summary a recursive reference - and we all know what recursive references can do in a scenario of transcribing one set of language into a series of numbers (!) Lovely - really fun. Liked Sir Ian's very quiet aside "Hello Eddie"
15. ## Understanding Reality

Talking of Shakespeare - there is the famous line from Two Gentlemen Who is Silvia? what is she, That all our swains commend her? Holy, fair, and wise is she; The heaven such grace did lend her, That she might admirèd be. The first line was once read by an angry and vindictive actor as Who is? Silvia? What! Is She?? [imagine vicious gossip talking about a third party] But, obvious punctuation errors aside, reading the glorious poem by WS it is hard to believe that this can be shorn of context and survive.
16. ## Understanding Reality

Then you are not discussing language - divorcing language from source is not possible; even if we do not know the source we will create a placeholder for that source, moreover even in the extreme example in which we believe there is no source that information will colour a listeners perception. And everything we do in the process of comprehension is contextualized by the source. I would say you are the one making an unjustified, and unnatural assumption; that language can be separated from speaker, situation, and listener. You must reduce in order to simplify for an experiment or model -
17. ## Infinite coin flip probability

It is the Ramanujan Summation - which gives an answer to the value of an infinite divergent series; in normal use there is no sum to an infinite divergent series - this is a special version which bears passing resemblance to the sum and allows further study of the concept. You are also correct in that it is used in zeta function methodologies I have read that Ramanujan summation is also used in normalization of certain quantum field theories - which in turn give positive predictions in terms of real world results. So it is weird and a bit unwholesome but there is definitely very importa
18. ## Virtual particles and fields

"(those are QM equations which do not apply just to photons)" - OK so this was the bit I was unsure of; thanks. Thinking more - I guess the frequency of the graviton, just like that of the gravitation radiation, will be twice the of frequency of the varying mass system (eg twice the frequency of rotation in the LIGO event); it's quadrapole - two peaks for each complete cycle of driver
19. ## Understanding Reality

Are there not multiple scenarios in which the listener's and communicator's credence levels are identical but the presence of a third party and more importantly the third party's knowledge/expected credence (ie expected by Listener & Communicator) are the crucial factor? Thus the $Message^{\ Communicator}_{\ Listener}(x_1, x_2, P_{third\ party}\left(x_1,x_2,...\ x_n\right) , \cdots,x_i , \cdots , x_n)$ is actually contingent on a probability. There is nothing in the communication (ie that would be represented by x1,x2 etc) which deals with the third party's expecte
20. ## Virtual particles and fields

Great answer - would quibble only this "I don't think it can accumulate energy. (I think the photon is unique in coming in a range of wavelengths/energies." The graviton - as the boson of a gravitational radiation (ie not as the virtual boson of gravity) - can hold any frequency and will reflect the period of the quadrapole which generated it just as the real photon does (obs not quadrapole etc) . I also think that Energy will still be proportional to frequency although I do not know if it is still as straight forward as E=hf
21. ## How do you resist delicious junk food ?

That sounds based on a little experiment run by Morgan Spurlock - he of "Supersize Me" - a selection of McDonalds "food" was put in bell jars and watched over a period of months. Lots of the food remained fairly intact and was not colonised by mould or other microorganisms - flies, I think, were excluded
22. ## If you want to learn rocket science intuition...

Doing the in-game tutorials. Also spending too much time trying to get my oldish pc to dual boot Win10 & Ubuntu. My laptop is melting trying to run Ksp on win10
23. ## Religious tangent from Alternatives to Evolution Theory

! Moderator Note Bimbo36 for your guidance; proselyting quotes from your holy book of choice are NEVER acceptable. I have trashed the religious follow up in the biology forum. Even the religion forum is for discussion of religion - not for conversion, nor for proclamations of faith. In a rational investigation an injunction from a holy book has no place and will nearly always be met with scorn and often with modnotes and warnings.
24. ## What are some scientific alternatives to the theory of evolution?

! Moderator Note Phi made it clear that there was to be no religious talk in any way in a science thread. Split off to the trash. Unacceptable behaviour.
25. ## How do you resist delicious junk food ?

Just for your guidance "I was used to doing something" is an acceptable usage; it means you have become accustomed to a practice "I used to doing something" is incorrect. A little better is "I used to eat it everyday" - I would prefer "In the past I ate it everyday"
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