Recent content by jvicens

  1. J

    Falling rod

    nvn, I understand what you said for my second question but I was initially still confused about the moment of inertia that should be used in these calculations I thought that the expression for potential energy 0.5xMxgxL was derived assuming the entire mass of the rod located at its center...
  2. J

    Falling rod

    jdstokes, nvn, Dick, I was searching the analysis for this particular falling rod problem as I'm currently trying to figure out the speed of the free end of the rod just before it hits the ground. If we are assuming all the mass of the rod as located at its center of mass when we calculate...
  3. J

    Gravity inside the earth

    Leaving aside all the technical reasons why such enterprise is not possible and using Newton's Law of Gravity shows that something very interesting would happen if you in fact manage to dig such a hole. If such a hole exists and you jump into it, you will experience accelerated motion towards...
  4. J

    Strong nuclear force and Iron nucleus

    Astronuc, jtbell, Thanks for your replies and the links. I got it now!
  5. J

    Strong nuclear force and Iron nucleus

    While reading the book " Cosmic Catastrophes. Supernovae, Gamma-Ray Bursts and Adventures in Hyperspace" by J.Craig Wheeler I came across this line: "By the happenstance of the nature of the strong nuclear force among protons and neutrons, the fifty-six particles of an iron nucleus are more...
  6. J

    Refraction Index vs. Material Thickness

    This is exactly the point and the reason for my question. If you start taking layers of atoms off from that reflective coating one after another, how many can you leave untouched before the refractive index changes and the beam of light refracts with a different angle?
  7. J

    Refraction Index vs. Material Thickness

    Take a beam of monochromatic light pointed at a sheet of quartz 2" thick. The beam is striking the surface of the quartz at a fixed angle different than zero. Part of the beam will be reflected and another part of the beam will be refracted. Its exact path through the sheet will depend on the...
  8. J

    Kinetic energy from rain drops

    Hi, I searched some websites with information about average size and average speed of rain drops, which I used to calculate the kinetic energy of the rain drop just before it hits the ground. My original question was: Is ALL this kinetic energy transferred to the ground (assume a non-elastic...
  9. J

    The Rutherford Atom

    The following questions came to my mind while I was solving a problem involving a collision of an alpha particle with a thin metal foil. Although I got the right answer (the book just listed the answer but nothing about how to get it) I still have doubts about how the real physical process takes...
  10. J

    Schrodinger's Equation

    I never had a formal QM course but I'm jumping into it by myself. For the last four days I've tried to understand the "derivation" of Schrodinger's equation. As a matter of fact, as I now type this reply I have 5 books on my desk open in Schrodinger chapter. Of course I have not been able to...
  11. J

    Heisenberg Uncertainty Principle - h/(4.Phi) versus h/(2.Phi)

    Heisenberg Uncertainty Principle - h/(4.Pi) versus h/(2.Pi) What's the reason behind the factor 2 in the way some books/papers present Heisenberg Uncertainty Principle? h/(4.Pi) versus h/(2.Pi) When in history did this discrepancy arise and who was responsible for that? Ultimately, which...
  12. J

    Tensor identity - Help

    Guys, thanks to you help I got it right this time after some thinking and some calculations. I realized one of my problems was the fact that when I was looking at a_{ij}=a_{ji} I was thinking of it as when we say a=b The way I should look at that expression is not isolated from the rest...
  13. J

    Tensor identity - Help

    I'm having some trouble to prove the following tensor identity shown below in Einstein's summation convention: (a_{ij}+a_{ji})x_{i}x_{j}=2a_{ij}x_{i}x_{j} I expanded the terms but when I did group them I didn't get the identity. The only way I could get the identity is if a_{ij}=a_{ji}...
  14. J

    Derivate the forumla for the acceleration due to gravity

    If you have trouble getting the planet's weight then you could still use another not-so-practical method to measure "g". You can get on a rocket on that planet or celestial body you want to measure "g" at. Start the engines and accelerate until your velocity (Vel) is such that you manage to...
  15. J

    Mathematica The Mathematical Theory of Black Holes

    I'm looking for the following book: The Mathematical Theory of Black Holes by Chandrasekhar, S. I have not been able to find it. Do you know where I can buy one, old or new?