Recent content by Ratpigeon

  1. R

    Time evolution of a particle in an ISW after the well

    Homework Statement How does the state of a particle in an ISW evolve with time after the width of the well doubles - from a to 2a If the particle starts in the ground state of the half width well, then immediately after the well doubles it will be undisturbed therefore the initial wave...
  2. R

    Is it possible for a chaotic system to have non-chaotic trajectories?

    Thanks - I probably should have known that, I was just put out when my plot of the chaotic-ness of a system turned out to be... chaotic. ;P
  3. R

    Equilibrium solutions in double well potential duffing oscillator

    I'd done all the linearising stuff - I found my problem; I needed to use a Jacobean matrix, instead of just a system
  4. R

    Is it possible for a chaotic system to have non-chaotic trajectories?

    Homework Statement I'm working on an assignment about the chaotic behaviour of the Duffing Oscillator, using Wolfram Mathematica, which has a package that can be used to calculate Lyapunov exponents. From looking the oscillator up online, I have a set of parameters that result in...
  5. R

    Equilibrium solutions in double well potential duffing oscillator

    Homework Statement I am trying to show that for a duffing oscillator described by x''+2g x'+ax+bx^3=0 with a<0, b>0 the equilibria at x=+- \sqrt{-a/b} are stable Homework Equations I used coupled equations, and the characteristic equation of a linear system The Attempt at a Solution...
  6. R

    Proving IJ is an Ideal When S is Not: A Case Study

    Homework Statement Show that if I and J are ideals of the (commutative) ring; R then S={xy|x in I y in J} is not necessarily an ideal but the set of finite sums IJ={Ʃ(xvyv)|xvin I yvin J} is (and called the product ideal). Homework Equations An ideal satisfies the properties For...
  7. R

    Residue Calculus integrate Sqrt(x)ln(x)/(1+x^2)

    Thanks thatreally helped. i got it out now
  8. R

    Residue Calculus integrate Sqrt(x)ln(x)/(1+x^2)

    Homework Statement Integrate from zero to infinity; f(x)=\sqrt(x)log(x)/(x^2+1) Homework Equations Branch cut makes log(z)= ln|z|+i Arg(z) Poles are at +/- i and Res(z=i) is \pi/4 e^(i \pi/4) I'll need to close the contour; probably as an annullus in the top half of the...
  9. R

    Determining order of the poles in z/(e^z-1)

    Right - got them. I got my brain stuck on taylor series, when I needed L'hopitals rule. Thanks. They're simple poles with limits z->z_0=z_0, right? :)
  10. R

    Determining order of the poles in z/(e^z-1)

    Homework Statement Find the order of the poles of f(z)=z/(e^z-1) Homework Equations The poles are at z=2 π i k k\inZ\0 (Because at z=0 f(z) has a removable singularity -set f(0)=1) The Attempt at a Solution I tried using the Taylor series of e^z - \sumz^n/n! But I just...
  11. R

    Particle moving along a parabola

    For part (i) - you are right, For part (ii) you have used s_x instead of V_x to determine V_y For part (iii) - yes, the acceleration is constant, but it is not equal to C; but maybe try determining the total acceleration, and the acceleration in the x direction instead of differentiating...
  12. R

    The baseball pitcher on an asteroid

    For part (b) you should use the equation PE=mgh (where m is the mass of the object, g is the gravitational force on the object, and h is the height of the object) You know what the initial kinetic energy is, and that at the peak of the throw; the potential energy will be equal to the the...
  13. R

    D'Alembert question - boundary conditions parts

    Homework Statement I have a general wave equation on the half line utt-c2uxx=0 u(x,0)=α(x) ut(x,0)=β(x) and the boundary condition; ut(0,t)=cηux where α is α extended as an odd function to the real line (and same for β) I have to find the d'alembert solution for x>=0; and show that in...
  14. R

    How Does Fourier Analysis Reveal the Series Expansion of Coth(pi)?

    wait, no, I got it. The denominator is 2 sinh(pi) and the numerator is twice the Fourier series at Pi - which is sinH(pi) multiplied by the series I want. Thanks! :)
  15. R

    How Does Fourier Analysis Reveal the Series Expansion of Coth(pi)?

    And that let's me calculate e^pi+e^-pi from my Fourier series at Pi; but how do I get e^pi-e^-pi for the denominator then?
Back
Top