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  1. Ed Aboud

    Double integral, cylindrical coordinates

    So I plotted it out, and by inspection I concluded that the limits are: 0 \le r \le 3 0 \le z \le 3 0 \le \theta \le 2 \pi However, I can't get past the integral: \iiint_V r \sqrt{r^2 + z^2} \,dr\,dz\,d \theta gives \iint_V \frac{1}{3} (r^2 + z^2)^(3/2) \,dz\,d \theta...
  2. Ed Aboud

    Double integral, cylindrical coordinates

    Apologies but I still can't get it to work out. My limits are: 3 \le r \le z 3 \le z \le r 0 \le \theta \le 2 \pi I'm fairly sure this is wrong, but can't figure out the correct ones
  3. Ed Aboud

    Double integral, cylindrical coordinates

    Thanks for your reply! So am I correct in saying: 3 \le r \le 9 ? Correction: 3 \le r \le z ?
  4. Ed Aboud

    Double integral, cylindrical coordinates

    1. Homework Statement The problem states: Use cylindrical coordinates to evaluate \iiint_V \sqrt{x^2 +y^2 +z^2} \,dx\,dy\,dz where V is the region bounded by the plane z = 3 and the cone z = \sqrt{x^2 + y^2} 2. Homework Equations x = r cos( \theta ) y = r sin( \theta )...
  5. Ed Aboud

    Determine the most probable radius for a 2s orbital (Hydrogen atom)

    Stuck on this problem also!! I get to a stage where I get a massive cubic equation...I'm assuming I've gone wrong somewhere... Any help? Or any online resources where the problem is worked through...?
  6. Ed Aboud

    Circuit breaker problem

    I was thinking along the lines of this, but I noticed that on each circuit breaker it says 20A and there are around 30 of them. Does that make a difference?
  7. Ed Aboud

    Circuit breaker problem

    Haha yeah it is the electrical panel, but its actually made of metal. I still don't understand why that fuse blew instead of one of the circuit breakers switching?
  8. Ed Aboud

    Circuit breaker problem

    Thanks dlgoff for the prompt reply. I'm not too sure about this. Would the circuit breakers not already be hot considering I had many devices on at the time? Thanks Ed
  9. Ed Aboud

    Circuit breaker problem

    Hi all! I have an issue with the circuit breaker in my house and was wondering would anyone be able to shed some light on whats going on. So last night, I plugged in the hoover and all the electrical devices in my house switched off. I wasn't surprised as I had many devices on at the time so I...
  10. Ed Aboud

    Mathematica Prompt user to enter mathematical function

    Hi all, I am trying to prompt the user to enter a mathematical function in matlab. Any suggestions on how to do this? I have looked at the inline functions but I am not sure how to code it. Any help is greatly appreciated. Ed
  11. Ed Aboud

    Vector division or inversion

    https://www.physicsforums.com/showthread.php?t=226881 May be of help jasper...
  12. Ed Aboud

    Analytical Mechanics: An Introduction

    Bump Any recommendations for a text which provides an introduction to Lagrangian mechanics and continues on to Hamiltonian mechanics?
  13. Ed Aboud

    Conservation of charge problem

    Hi Sarah, Ok so I think you should revise the principle of conservation of charge. In this case, a useful approach would be to remember that the charge on the left hand side of an equation is equal to the charge on the right hand side of the equation. For example, analyse question a) p...
  14. Ed Aboud

    Where was the big bang singularity?

    Everywhere and nowhere! Our entire foundation is the cosmological principle, telling us that no point in the Universe is special. If there was a particular point where the "Bang" happened, that would clearly be a special point and violate the cosmological principle. Rather, space and time...
  15. Ed Aboud

    Gold and Silver

    Well there are only a few properties that differ greatly between gold and silver. For example atomic weight/number and therefore its specific gravity, boiling point... I'm guessing the solution will be of some relevance to Archimedes... So I feel that you're on the right track by measuring the...
  16. Ed Aboud

    How does a rocket work in space

    Or think of it as conservation of momentum. Momentum of expelled fuel = Momentum of rocket
  17. Ed Aboud

    How did they rewrite this?

    Multiply the numerator and denominator of A by the complex conjugate of -2 + 4i
  18. Ed Aboud

    Photoelectric effect with free electrons.

    1. Homework Statement Is it possible for a gamma ray to interact with a free electron by mean of the photoelectric effect? 2. Homework Equations 3. The Attempt at a Solution I'm not really sure. I think the answer is no simply because of the mechanics of the photoelectric...
  19. Ed Aboud

    Integration Question

    So du = \frac{dx}{2\sqrt{x}} 2 \int sin(u) du Cool, thanks.
  20. Ed Aboud

    Integration Question

    1. Homework Statement \int \frac{sin(\sqrt{x})}{\sqrt{x}} dx 2. Homework Equations 3. The Attempt at a Solution I'm not too sure how to approach this. The only thing that rings a bell at this moment is \lim_{x\to\0} \frac{sinx}{x} = 1 and I don't feel that it is of any...
  21. Ed Aboud

    Flux through each face on a cube

    Ah right I see now. Thanks very much, was thinking about this completely the wrong way.
  22. Ed Aboud

    Flux through each face on a cube

    I'm not sure why is it 6q ? If there is only one charge of magnitude 1q surely the flux is q/\epsilon_0
  23. Ed Aboud

    Special Relativity Question

    1. Homework Statement Show that if motion could occur at arbitrary speed, then time travel would be possible. 2. Homework Equations 3. The Attempt at a Solution I'm not sure where to start of. I'm guessing that it has something to do with the light-cone and space-like vectors...
  24. Ed Aboud

    Flux through each face on a cube

    1. Homework Statement A point charge q is placed at one corner of a cube of edge a. What is the flux through each of the cube faces? 2. Homework Equations 3. The Attempt at a Solution I drew a diagram of the situation. I'm pretty sure that I should use Gauss' Law and some...
  25. Ed Aboud

    Laplace operator help

    Actually its cool, I got it. Thanks for the help!
  26. Ed Aboud

    Laplace operator help

    I'm not really sure how to apply the chain rule in this case. Is there any general formula that I can use?
  27. Ed Aboud

    Laplace operator help

    1. Homework Statement Let x = (x,y,z) . Recall that the vector x is determined by its direction and length r = |x| = \sqrt{x^2 + y^2 + z^2} and assume we are given a function f which depends only on the length of x f = f(r) Show that \Delta f = f'' + \frac{2}{r} f'...
  28. Ed Aboud

    Mechanics question

    Oh ok, well thanks for trying anyway. Can anyone else help please?
  29. Ed Aboud

    Coordinate geometry of the circle question

    Ok cool thanks so it is R^2 -12R +20 = 0 R=2 and R=10 Therefore the equations of the circles are (x- R)^2+ (y+ R)^2= R^2 (x- 2)^2+ (y+ 2)^2= R^2 and (x- 10)^2+ (y+ 10)^2= R^2 Just out of curiosity what was wrong with my original attempt?
  30. Ed Aboud

    Coordinate geometry of the circle question

    Yeah so you get R^2 + 4R + 20 = 0 this has complex roots as well....
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