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  1. Z

    Liquid drop contact angle: THF, mica & graphite

    Thanks, I will check out the book. Indeed you are correct about splitting hairs, I'm thinking that it might be best to just state that the angle is very small, but I would like to put a upper limit on it, I may have to make an estimate somehow. I will still have a look in Adamson just in case...
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    Liquid drop contact angle: THF, mica & graphite

    This is a long shot, but maybe someone will know or can point me in the right direction. I'm looking for an experimental value for the contact angle between tetrahydrofuran (THF) with both mica and graphite substrates. I've done numerous googling and also did a search on the web of knowledge...
  3. Z

    Brain Teaser - How does 12=11?

    I would say that the first humans used thier fingers to count from 1 to 10, and anything above that would be considered "a lot of damn numbers". In this sense, they would consider 12=11=many :-) The real "answer" is probably having changed based without indicating it though (which is cheating...
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    Inverse pendulum on a cart

    This isn't directly answering your question but it may help at some point. Something I read once about balance is that it's not about making tiny corrections so you are always at the equilibrium position (i.e., in your case when theta = 0), it's about gently oscillating back and forth about the...
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    Q on solution of Spherical Harmonic

    We know "the constant" in eqn (3) is constant, so we have the freedom to call it *whatever* we want, as long as it is indeed constant. Calling it -m^2 is just a trick because it simplifies the algebra later on (when you get the equation (4)). Another way to explain it is that the differential...
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    Greater kinetic friction

    hmmm interesting question. I would say it would have something to do with a special material for the object that's moving, such that, as the object moves and the contact surface heats up due to friction, the surface undergoes some physical or chemical change so that its coefficient of friction...
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    Summer job in Physics for UK student

    Hi leila, Do you know if you university offers summer placements where you get to go abroad? (my university, the university of birmingham, does one where you go to france). Your physics department will definatly have international ties with other universities, and even if there isn't a...
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    Self-learned physicist or pipe dream?

    When you do a PhD, its very specific piece of research, and by research I mean you actually work on something that no one has done before. You don't do a PhD in physics as such, it would be a PhD in nuclear physics, solid state physics, particle physics, astrophysics, or theoretical physics...
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    Whats wrong with this free energy experiment

    What is your native language? some of what you say does not make sense - when you say axe, do you mean axes? (x.y,z axes?). I agree with you that it is not good to blindly accept all of physics, but you need to explain yourself more clearly. Do not forget that it is *possible* that you...
  10. Z

    LaTeX Run LaTeX off of a USB Drive?

    Is it possible to "install" LaTeX (for windows) on, say, a USB pocketdrive? Or better yet could I just copy over all the directories from an existing computer and then be able to compile .tex files using the packages I have installed? I know you can get other pieces of software that run off...
  11. Z

    Resonant frequencies

    You do this by hitting the tuning fork really hard, or not very hard at all, there will still be a sound but it won't be resonating (just like if you push someone on a swing really weakly or really hard, they wil lstill move by they won't move in the "resonating" fashion). Hmm, just re-read...
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    Temperature - is that the right word?

    ...to clarify a bit on my last post. Thinking about it, really it's your brain that 'does the measuring' of the temperature, and it measures the temperature of your skin. Since your skins temperature is linked to the temperature of the air around it, you (or your brain) can infer the...
  13. Z

    Temperature - is that the right word?

    What is your skin (or special cells in your skin etc, I'm not sure exactly) measuring the temperature of? thats the question you need to ask to solve the debate with your friend. Your friend says it is measuring the temperature of the air (which seems very reasonable indeed!) and so he came...
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    Scientific notation question

    From a computer programming point of view the D means the number is stored as double precision where as E is stored as single precision (for exmaple this is the notiation used in the fortran programming language, but it may apply to other languages, im not sure). If you arent doing any...
  15. Z

    Good Website for Unit Conversions

    with google you can also type things like "1 mile in centimeters" as well as "1ev=". google also acts as a basic calculator which can sometimes be better than the default windows calculator as you can write out a long calculation and then get google to evaluate it.
  16. Z

    Ladder Operators for a SHO

    Thanks for the replys...i think my actual problem is between the mathematics and the actual physics. You two guys seems to think very mathematically...where my error came from was my interpretation of the *worded* definititon of the two ladder operators. Thats why I came up with the incorrect...
  17. Z

    Ladder Operators for a SHO

    Hi, Having trouble understanding something here, hoping someone can help...when dealing with a SHO, we can define two ladder operators a and a-dagger. The way I understand it is, applying a-dagger to an eigenstate of H (and that has, for instance, eigenvalue E) will give us a new eigenstate...
  18. Z

    Quick question on notation

    Thank you all for the answers!
  19. Z

    Quick question on notation

    Hi, How would you write mathematically "As P approaches zero from the negative side". Is it something like P --> -0 ? Thanks!
  20. Z

    Laser Modes/Free Spectral Range

    Thanks, it makes a lot more sense now, and also, thinking about what the actual words mean in FSR, the range (ie a distance) that is free of spectral lines? (ie the distance betweeen spectral lines, or different modes since the modes correspond to slightly different wavelengths). I am aware...
  21. Z

    Electomagnetic Induction

    ok so you have a strip of magnetic material...its variably magnetized. This means that the magnetic field is different of different parts of the strip. Now what happens when you move the strip past a coil of wire? well we know the strip is magnetized so produces a magnetic field, so really...
  22. Z

    Laser Modes/Free Spectral Range

    thank you for the reply Claude. So the FSR is the longitudinal spacing of the modes only when the mirrors (or reflecting surfaces) are planar? otherwise we just just the term longitudinal spacing? About my second question, I was asking if the \Delta \lambda equation is correct for a laser...
  23. Z

    Does light refract like they say it does

    selfadjoint, not everyone knows what latex is you know...
  24. Z

    Laser Modes/Free Spectral Range

    Hi, As we know, lasers have longitudinal modes, the seperation between neighbouring modes (measured in frequency) is: \Delta \nu = \frac{c}{2L} and by using the fact that: \frac{\Delta \nu}{\nu} = \frac{\Delta \lambda}{\lambda} we obtain the seperation between neightbouring modes...
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    Simpson's rule can solve cubics exactly

    having thought about it this is the only thing i can think of: int_{x_0}^{x_0+2h} -----> int_{x_0 -x_0}^{x_0+2h-x_0} so, thats saying that the integral doesnt lose any generality by subtracting x_0 (a constant) from both the upper and lower limits (i dont know for certain i can do this...
  26. Z

    Simpson's rule can solve cubics exactly

    Thanks for the reply. Could you tell me that if the integral is from x_0 to x_0 + 2h then can i set x_0 = 0 and it still be a proof (it's a lot simplier if i do)? or have i lost generality? Thanks again!
  27. Z

    Simpson's rule can solve cubics exactly

    Simpson's rule can solve cubics exactly...(as well as quadratics which makes sense) the question is why? ive googled around and cant find an explanation, although it is just stated as being true. Can someone offer and explanation or a website? Thanks
  28. Z

    Double slit wavefunction

    hmmm, my kets didnt come out, but still means the same thing! TIA for any replies!
  29. Z

    Double slit wavefunction

    Hi, just need a quick confirmation im right with something! :) If we are considering electrons (for example) going through the double slit experiment one at a time would it be correct to define the wavefunction for the electron as follows? \Ket{\Psi} = C_1\Ket{\phi_1} + C_2\Ket{\phi_2}...
  30. Z

    The measurement 'problem'

    thanks, didnt think to look there, i thought they only had papers that were not peer reviewed/published yet. I look at all his papers but stillcant find the one lalbatros mentioned. There is a "why quantum theory" but it doesnt seem to mention measurement at the start :(
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