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  1. epenguin

    How is this graph Hamiltonian and Eulerian?

    It is not Eulerian because there is one node with an odd degree. :oldtongue: :oldbiggrin:
  2. epenguin

    Chemistry Finding the pH of this acid and its sodium salt solution

    Oh well, this is not the first or second time that for a problem in this area I asked for the relevant equations and that ended the thread. So I suppose as soon as you write them down you know what to do. (Ready to help but I do wonder sometimes when I see a question about some extremely...
  3. epenguin

    Today I learned

    I abstained from saying so as I thought few people here would get it. :oldsmile:
  4. epenguin

    Today I learned

    Naughty, subversive, anti-intellectual but great poetry with the memorable line "Hanging like bats in a world of inverted values"...
  5. epenguin

    I What techniques and equipment are used to measure the length of one meter (without circular reasoning)?

    In illustration, if I remember correctly, the Coulomb and Ampere were alternately defined by an electrochemical-gravimetric and an electromagnetic (force) definition according to what was the most precisely measurable at different times. Whenever there is a redefinition it is always made so...
  6. epenguin

    I want to study electrical electronics but i don't know about it

    Not enough information about you to usefully advise. Big difference if you are ≈18 and decisions imminent (in which case information about studies/knowledge so far also useful) or 14 in which case general strategy more to the point. Also important where you are, Himalayas or New York? - and what...
  7. epenguin

    I How did students manage to study the required Mathematics for Physics

    That's a good question.Not every student can honestly say they have your problem of doing too much! I would say be reasonable and rational, the exercises are meant really to help you; if they are allowed to get on top of you, if you make it a question of self esteem, there is a point where they...
  8. epenguin

    I How did students manage to study the required Mathematics for Physics

    Can't think of any offhand, and I don't think I agree, nor do I think would most teachers or homework helpers here. Most would say that if you cannot apply the maths, which is tested in exercises and problems, you cannot be said to have learnt it. (Similarly for any other subject.) Why do...
  9. epenguin

    I How did students manage to study the required Mathematics for Physics

    Provisionally, here is a stab at a few considerations based on my limited knowledge. For the 18th century it seems to me the question hardly arises. There was essentially no organised formal teaching of physics. In that century universities were little concerned with physics or any other...
  10. epenguin

    PF Photo Contest - She Blinded Me With Science (2/15-2/21)

    Het wonder is geen wonder This is the mathematician, engineer and latterly, bird sanctuary, Simon Stevin. or more exactly it is his statue in SimonStevinsplein in his (probable) town of birth, Bruges. If you have never heard of him, to read him up, e.g. https://en.wikipedia.org/wiki/Simon_Stevin...
  11. epenguin

    How do you sketch (x^2-5)^2+y^2=16 without a calculator or software?

    You also easily get x co-ordinates of four points where y = 0, and symmetry tells you something about their special nature.
  12. epenguin

    Programs Seeking advice on how to search for a Graduate School in Molecular Biology

    You will have done a BS in molecular biology - surely there are some areas that interest or attract you more than others? Pretty different membrane protein dynamics from evolutionary relationships from photosynthesis (though some relation between them and everything else). So you can now narrow...
  13. epenguin

    Chemistry Finding the pH of this acid and its sodium salt solution

    The template asks you to write down the relevant equations. You have not done so, not even the ones you used to get your result so far. It is however however an essential step for this kind of problem.
  14. epenguin

    Today I learned

    Today I learned from JT Bell here https://www.physicsforums.com/threads/mini-road-trip-dont-take-this-place-for-granite.983859/ that there really was a choo choo in Chattanooga. Once I only knew the song. The existence of a real place became a bit more assured when I saw The Glenn Miller film...
  15. epenguin

    PF Photo Contest - Things Are Looking Up (2/1-2/7)

    Looking up to - it doesn't get any higher. :oldwink: If the sight doesn't convert you, some days those windows can be opened and you hear a choir sing. (Celebrated octagon in Ely Cathedral. The whole is a structure in Timber, quite discussed by engineers. engineering times structure ely octagon...
  16. epenguin

    News BREXIT - more good than bad or more bad than good?

    For information, the principle you quote here is known as 'subsidiarity'. There had been indeed objections to what was perceived as an arrogation of powers to 'Brussels'. You cannot contest that there are perfectly good reasons for tackling many problems at the level of the European Union...
  17. epenguin

    Total differential

    I hope you do understand, not just you 'thought you had to' and now think 'you have to' do something different. Have you quoted the question exactly? The exact answer to the question as quoted by you is (2 + 0.02)×(3 - 0.03)4 - 2×3 = ... Yours is an answer to a question like "use differential...
  18. epenguin

    News BREXIT - more good than bad or more bad than good?

    We are looking like an evolutionary irrelevance, but maybe over a longer period some of our genes and memes....
  19. epenguin

    News BREXIT - more good than bad or more bad than good?

    The phrase has been around (if I am not mistaken only since about last year - though the phenomenon longer) post-truth. Or the 'post-truth society'. I found the case of the kippers striking. I don't know if Jonathan perceived the same as I did. That when Boris said it, nobody was much concerned...
  20. epenguin

    News BREXIT - more good than bad or more bad than good?

    Well yes, the manufacture of an individual car is now often cross-border - part of it is constructed in one country then transported to e.g. the UK where various other parts are added then it is transported elsewhere for further work - the transport is calculated down to the hour, maybe it goes...
  21. epenguin

    News BREXIT - more good than bad or more bad than good?

    " many just hopeful the divorce would mark the end an anguished chapter in their country’s history." There are many illusions about this process. The above is one of them. it is true that a lot of people of the UK are, after the Brexit issue has dominated U.K. politics for 4 years, bored with...
  22. epenguin

    PF Photo Contest - The Sound of Music (1/25-1/31)

    My photos were also disqualified numerous times before :oldsmile: for excessive Mb, but now the former limitations have been lifted you have still made me feel guilty and abusive of PF resources :blushing: for not trying to reduce usage which I gathered is done when posting from hosting sites...
  23. epenguin

    PF Photo Contest - The Sound of Music (1/25-1/31)

    You said preferably post from an image-hosting site like imgur. From goodwill to save your bandwidth, after days puzzling how to translate their instructions into actions looks like I've done it. But then it is framed by the rubbish you see - how do I get rid of that? And if possible make the...
  24. epenguin

    Best Intermediate Algebra textbooks?

    Your description of your level is confused and confusing. Your profile gives you 'undergrad' which to me means at University having done the school syllabus. Plus your favorite areas are not pure math, which makes some difference to recommendations. Though maybe you want to extend outside the...
  25. epenguin

    What would be the impact of the discovery of the Graviton in the world?

    When I am in the company of scientists, I feel like a shabby curate who has strayed by mistake into a drawing room full of dukes." W. H. Auden For ordinary persons and parsons, can some physicist tell us what it is supposed to be like? I don't suppose you could ever see one. You can't see a...
  26. epenguin

    PF Photo Contest - You Look Rather Down (1/18-1/24)

    OK, tame. On the other hand...
  27. epenguin

    Why does dividing by ##\sin^2 x## solve the integral?

    For how did they arrive at that method, I suspect they are teachers or textbook writers who spend a lot of time on this functions and have a lot of experience in the various ins and outs about throwing about the various trigonometric functions and their combinations and have got to know that...
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