Explanation Definition and 961 Threads

  1. B

    CMBR - a possible alternative explanation?

    How can we be sure that the Cosmic Microwave Backgound Radiation is a relic of the big bang and not a reflected echo of the sun's solar wind after it's interaction with the heliopause? I ask this because I read an article some years ago which indicated that one of the voyagers had detected a...
  2. W

    Solar Cycle & Explanation for Recent Changes?

    Is the Sun heading towards a Maunder Minimum? [PLAIN]http://science.nasa.gov/headlines/y2006/10may_longrange.htm[/URL] The following is an excerpt from the above link: The sun's "Great Conveyor Belt" And from the next link, it appears there was a failed solar magnetic field...
  3. N

    Understanding Lenz's Law - Get a Clear Explanation Now

    i am having so much difficulty understanding lenz's law. i don't know what it means and how to use it. will someone please give me a good explanation for it because my book SUCKS and I'm having a very hard time understanding this hard(and stupid) topic so please help me.
  4. T

    Solving My First Vector Problem: Answers & Explanation

    I JUST started adding vectors.. as in.. last class. I got a ton of questions, and have done three of them. The answers are given, but I got them wrong. I'll follow the little template already given: Homework Statement What is the net force on a stack of books which are applied two forces...
  5. L

    Sky colour explanation by scattering

    I have done a little research on the internet and I would like to ask my concept is correct or not. 1) Sky is blue As the effect of rayleigh scattering is more effective for shorter wavelength, blue light scatter more than others (e.g. red). Furthermore, our eyes are more sensitive to blue...
  6. H

    Carlip's explanation of lack of gravitational aberration

    Last month I asked here whether there's a consensus about Van Flandern's speculations about the speed of gravity. I quickly learned that he's not well-regarded. Fine. I was hoping to be able to get something out of Steve Carlip's explanation for how GR explains the apparent almost...
  7. R

    Does hot water really freeze faster than cold water?

    1. A woman informs her engineer husband that "hot water will freeze faster than cold water". He calls this statement nonsense. She answers by saying that she had actually timed the freezing process for ice trays in the home refrigerator and found that the hot water does indeed freeze faster. As...
  8. T

    Am I delusional or is there a logical explanation for this

    I've always wondered since I was a kid, I would lay down and have a blanket over my eyes sometimes while looking through it during daylight or at a light. If I focused just right, I would slowly see squiggly lines and things just slowly floating by like a transparent layer over what I normally...
  9. Z

    On explanation of negative energy states and electron pair creation

    Dirac's theory of the electron predicted that there were identical particles of equal mass but of negative energy. He appealed to the Pauli exclusion principle and proposed that there was a negative energy 'sea' of electrons that was full up to -2mc^2 in order to answer critics that positive...
  10. B

    Eigenfunctions problem - i have the answer, explanation required

    Homework Statement Now in a revision lecture given a few weeks ago, the lecturer gave this as the answer. The Attempt at a Solution No I think generally I'm fine with it (apart from it doesn't seem very obvious that this is what you should do with the maths!). BUT 1)...
  11. C

    String Theory: a layman's explanation [joke]

    If one goes to a bookstore, one can find lots of books about String Theory. Unfortunately, many of these books are very difficult to comprehend; not everyone has the background necessary to appreciate these great works. To satisfy the curiosity of these people, I have decided to write this...
  12. P

    Intuitive explanation why frequency is fixed

    From treating light as a wave it is possible using Huygen’s theory to deduce that the frequency of the light will not change whether in vacuum or some other material. I have seen a mathematical proof of it and understand it but is there an intuitive explanation for it? Does it match Maxwell...
  13. P

    Why does the partial of 2y^2e^(xy^2) equal 4ye^(xy^2)?

    \frac{\partial_P}{\partial_y}(2ysinxcosx-y+2y^2e^{(xy^2)} I worked the first part no problem, but the second part I needed a little help from my calculator. This is what I got: 2sinxcosx-1+4ye^{(xy^2)} My question is, why does the partial of 2y^2e^{(xy^2)} come out to 4ye^{(xy^2)}...
  14. H

    Scientific explanation of the Universe

    Unless we figure out time travel (laughable), there is no way to come to a scientific explanation of the universe. All the 'theories' we have on the universe's beginnings are nothing but hypotheses...and that includes the big bang 'theory'...which is currently being shot to **** (Back and to the...
  15. A

    Explaining Nuclear Fusion to Non-Sci Majors

    I need to explain fusion to some intro chem people, but they are really dense...Think this will work: *see picture
  16. B

    Scientific explanation of a chip pan fire + water

    Ok, I know what happens (big fireball : ) when you add water to a chip pan fire, but I'd really appreciate it if you guys (and gals) helped me out with SCIENTIFICALLY describing WHY adding water to the pan causes the fireball. It must contain words like "immiscible" and so on... Thanks in...
  17. S

    Explanation needed in angular acceleration

    Hi all, I am doing some homework from my textbook and I encountered this problem: "Starting from rest, a disk rotates about its central axis with constant angular acceleration. In 5.0 s, it rotates 25 rad. During that time, what are the magnitudes of (a) the angular acceleration and (b) the...
  18. K

    Physical explanation for camera DOF (depth of field)

    http://en.wikipedia.org/wiki/Depth_of_field" stands for the range that is sharp on a photograph. The bigger the diafragma (camera opening) the smaller the range that will be sharp on the picture. A bigger diafragma also means a shorter shutter opening (so the picture doesn't become too...
  19. G

    Resonance need explanation (No maths)

    I know that when the applied frequency on a mass is equal to the natural frequency, the mass resonates. It has a great amplitude as a result of this. But I don't know how somethings affect the resonant frequency. Like for a mass-spring system. 1) What effect would increasing the mass have...
  20. M

    What is the scientifical explanation of death?

    what is the scientifical (phycisistic) explanation of death? and what's the point in doing anything if we're just going to die? please, keep it short/simple, couse my head aches, and my english sucks..
  21. S

    VLE Calculations: Help and Explanation

    Sorry bout putting the question in the form of like a homework problem, just didnt know how to go bout asking what i wanted. Basically can anyone explain how to do VLE calculations.. So confused with the topic. Whats bubblepoint and dew mean.. Cheers. Hopefully this post is ok for...
  22. B

    Fourier Series: Simplified Explanation for Beginners

    Can someone explain this to me simply. I just plain do not get Fourier Series. I've got a question that says: show that f(x)=exp(-cx) for 0<x<pi =exp(cx) for -pi<x<0 can be written as a cosine series that's way too complicated for me to work out how to write here. I have no idea...
  23. Loren Booda

    How does Napier's logarithm make computing powers easier without calculus?

    How can one explain the Napierian logarithm without calculus?
  24. J

    Explanation of how a capacitor works?

    Could anyone give me a brief explanation of how a capacitor works? What does its I-V graph look like? Thanks
  25. B

    Brief explanation of what entropy is?

    Hi, could someone please give me a brief explanation of what entropy is? Due to my limited understanding what entropy actually is, most of the things I've read about it seem very vague. I've only been seeing entropy popping up in integrals and in sometimes in comments along the lines of entropy...
  26. L

    Debunking HUP explanation myth

    Hi, All my chemistry textbooks (thankfully not the physics ones) and my teachers (unfortunately including the physics ones) seem bent on 'explaining' the Heisenberg Position-Momentum Uncertainty Principle using the famous thought experiment of photons striking an electron, and not one of them...
  27. S

    Does string theory/M theory have an explanation for

    If there is an explanation, I would appreciate undersanding them 1. The speed of light being (approx) 300,000 kms/sec rather than some other value? 2. That the speed of light is the same no matter what frame of reference (as per Einstein's theories and I assume it must have) 3. What is...
  28. S

    What is the Determinant and Why Does It Matter in Linear Algebra?

    My lack of any shred of idea about the concept of the determinant is really beginning to bug me. Especially now that I have begun my Linear Algebra class. Is there anybody available to help explain (or link me to a good explanation) to me the idea behind it and what the value actually stands...
  29. C

    Elastic and Inelastic Collision explanation

    *** Elastic and Inelastic Collision explanation *** 1) Why energy and momentum are conserved in elastic collision? 2) Why only momentum is conserved in inelastic collision? Why energy is not conserved? Answers: Conservation of momentum is a consequence of Newton's third law. From the...
  30. B

    Explanation for term in formula, QFT

    Hi I've got a question about a term in a formula I've found in Mandl&Shaw's QFT book It's about equation 2.18 on page 31 L(t) = {\sum_i \delta \bf{x}_i {\cal L}_i \ ... Why is there a delta x_i when summing over all lagrangians for getting the lagrange-function for the whole...
  31. W

    Looking for explanation of randomness.

    Hi all, for some time I have been wondering about something I’m not too sure on. Please could someone tell me how randomness can exist? That is to say on a molecular level, or on any level things happening without cause or justification? Patterns may be too hard for us to currently understand or...
  32. C

    MOND gravity, an explanation please.

    Greetings, I've heard something to the effect that MOND can explain the rotation of galaxies, but the article was very fuzzy. Can someone please explain to me MOND... 1) How is MOND different from the inverse-square law? (math please) 2) What 'problems' in science does MOND...
  33. A

    Kinetic explanation of evaporation of boiling/Melting.

    Hi guys I am slightly confuse about a statement in the kinetic explanation for evaporation as well as melting. Firstly for the evaporation: "Thus the latent heat supplied in causing evaporation represents the potential energy gain of the escaping molecules plus the work needed to expand...
  34. usp8riot

    Explanation of gravity, am I in the ballpark?

    I was posting this on sciforums and it hasn't been debated yet so looking for opinions. But this forum is even better for physics discussions but I forgot the link to it since I used to visit here a couple years back. Anyhow, I will copy and paste my reply about gravitational forces: 'What...
  35. U

    I need an easy explanation for a flow formula

    In order to calculate flow rate when using a differential head pressure device, the simplified formula is Flow = (coefficient)(square root of the differential pressure) My question is why? Why the square root, can some explain this to me please? Thanks
  36. N

    Modeling Disease Spread: Differential Equation for Infected Individuals

    The spread of a disease in a community is modeled by the following differential equation: dy/dx = 0.2y - 0.02x where y is the number of infected individuals in thousands, and x the time in days. 1) Show the equation that for the family of 'curves' in the x-y plane for which dy/dx is a...
  37. I

    What is CAM-I and Why is it Important for Manufacturing?

    Need explanation, please~~ Hi I am looking for the definition, and purpose of: COmputer AIded Manufacturing International
  38. B

    Explanation of the wording - Electromagnetism Question

    Could someone explain the wording (and possibly see if I'm going the right way about it) of this question to me. What is the current required in the windings of a long solenoid that has 1000 turns uniformly distributed over a length of 0.400m, o produce at the centre of the solenoid a...
  39. Z

    Need and explanation of an Optics principle.

    There is a laser beam with a diameter D, in air that strikes a flat smooth piece of glass with angle @ and index of refraction of n. I need to derive and equation for the diameter of the beam in the glass wiht respect with n D, and @. I want to know why the beam's diameter would be effected by...
  40. B

    Explanation of Eq of Peskin's Intro to QFT Book

    Hi Can someone please explain to me Eq 2.30 in Schroeder's and Peskin's book? (page 21) how does he simplify the long equation of the commutator to this delta distribution? \imath\delta^(^3^)\ (x - x') Thanks
  41. R

    How Do I Find a Quartic Function with Given Inflection Points?

    Hey everyone, For math, I was given a quartic function. I was asked to find the coordinates of the points of inflection Q and R. Then to determine the points P and S, where the line QR intersects the quartic function again, and calculate the ratio PQ:QR:RS. So I found the points of...
  42. S

    How holography works (entire explanation)

    Would someone, PLEEEEAAAASSSEEE, explain here how holography actually works. ...I mean - I know (I've already read about it times and times again) - I know it has to do with interference patterns (interaction between two components of light (object and reference light)), I see it has to do...
  43. W

    A New Explanation for Venus' Retrograde Rotation

    Consider this scenario: a Mars-size object strikes a glancing blow at Venus's backside that's facing toward the Sun. The resultant debris cloud would then coalesce into a large moon having a retrograde orbit. Tidal friction would then slow down Venus' rotation until it was tidally locked to its...
  44. adrenaline

    Need Understandable Explanation Of Bell's Theorum

    Every once in a while I try to stretch my feeble mind and pick up layman books on quantum physics as a change of pace from the many clinical/medical journals I have to constantly keep up with. I have a BS in chemistry and understand basic quantum mechanics but as much as I try, I cannot fully...
  45. P

    Explanation why dosen't the electron fall into the nucleus?

    Since the nucleus of an atom is +charged and the electron is -charged, why doesn't at least one electron fall into the nucleus?
  46. S

    Mimicry: Evolution explanation?

    Hey, Just wondering: How does evolution explains the process by which some species, spceially from insects, have mimicry tactics for defense? Thx in advance, Mimicry: The phenomenon in which some species [the mimic] resembles another species [the model] and gains protection from the...
  47. V

    Understanding Baseball Bat Center of Mass: Seeking Explanation

    Hey, There is a question in my textbook that I don't understand the answer too. THey show a diagram of a baseball bat and say if the baseball bad it cut at the location of its center of mass, do the two pieces have the same mass? They say no, the piece with the handle will have less mass than...
  48. B

    Buoyancy-a bit of explanation please

    hello Buoyancy is the upward force exerted on an object immersed in fluid, and upward force on an object in a fluid is equal to the weight of the fluid that was displaced. If this bouyant force is less than the weight of the object itself, the object will be left with a net downward force...
  49. R

    Introductory explanation about dualities?

    Someboy can give me an introductory explanation about dualities? I mean, what are, how works in theory and what physical sense do have it? I have to start some study about using dualities in linearized gravity, so i'll be very helped if you have too some basic literature at respect. Specifically...
  50. I

    Please explanation will help me out

    Ok so far I have been thinking that an explosion is nothing else than a inelastic collision. So energy is lost and momentum is conserved therefore P_i = P_f , The problem asks for how much kinetic energy did each piece acquire in the explosion, I also know that there was 7800 J released. In...
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