Recent content by jorgeha

  1. J

    Can you change a planet's orbit by reducing its velocity?

    You're right! It wasn't a very well-thought example... However, it was just an illustration, thanks to all of you I've found the answer I wanted, thank you!
  2. J

    Can you change a planet's orbit by reducing its velocity?

    My question is, take Mars, say, and install a huge rocket engine on the ground pointing out the planet (obviously) and in the opposite direction of its velocity, so that if it is turned on, the planet is slowed. The rocket starts to work and Mars is slowed. If the loss of velocity goes little by...
  3. J

    Electromagnetic field disturbance if radiation disappears

    So we should now think of the electromagnetic field at a point of space like a superposition of fields: the one generated by the moving charge and the one generated by the "barrier" in reponse to the radiation? If the barrier was something like 100% reflexive (theoretically), would the...
  4. J

    Electromagnetic field disturbance if radiation disappears

    My doubt is, if light "carries" the information about the change of the electromagnetic field, if we absorb every radiation from that source (the yellow charge) in a region of space, will charges in that region feel the change in the electromagnetic field? If yes, then I don't understand the...
  5. J

    Electromagnetic field disturbance if radiation disappears

    Hi everyone! I've been reading about these topics (Feynman lectures and more on the internet and some books) but I still have a doubt, maybe because I haven't understood the whole of it. This is my doubt: Think of an imaginary situation in which we have an accelerating charge. The...
  6. J

    Other Physics Graduate Study - Which Area?

    This article may help you: http://www.sciencedirect.com/science/article/pii/S1097276509006418 Sadly I can't help you with the details, but this link may give you some interesting information about choosing a topic for research.
  7. J

    I Calculate the energy of the electron in a non-H like atom

    I was asking for a numerical calculation. I guessed it could only be an approximate answer but I didn't know to what extent. I'd like the most exact approach possible, if you could lead me to some articles or books about these calculations I would be grateful. Thanks.
  8. J

    I Calculate the energy of the electron in a non-H like atom

    Hello mates. I was doing some research about Rydberg atoms, and I came up with this question: what's the energy of an electron in n energy level in an atom which is NOT hydrogen-like, that is, an atom with more than 1 electron? How can we calculate it? What if the electron we are studying is in...
  9. J

    How to calculate the perpendicular tension?

    Thanks, that was my doubt!
  10. J

    How to calculate the perpendicular tension?

    Thank you very much for your answer. Do you know any other important concept I should learn? I will study that principle tomorrow :). I am studying with the Lectures, and they aren't like a textbook, I don't know which particular concepts I must know... do you know any other which will be useful...
  11. J

    How to calculate the perpendicular tension?

    Sadly, I haven't. I am studying with the Lectures and it isn't a very complete book (I mean, it isn't like a textbook). With the balance of moments, which other concepts do you think I should learn? Can you show me how to do it anyways? Thanks
  12. J

    How to calculate the perpendicular tension?

    Hello to everyone, merry christmas and happy new year! I was trying some exercises on the Feynman Lectures, on the topic of statics, and I came across with a problem which, simplified until where I am stuck, asks for the tension of a cable perpendicular to a bar with a weight on the top of it...
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