Recent content by Lazy Rat

  1. Lazy Rat

    Integration problem using u substitution

    thank you for your assistance chaps.
  2. Lazy Rat

    Integration problem using u substitution

    So rearranging I get ## dx = \frac {du\: L}{\pi} ## then the ## du ## part becomes the next step in ## \sin du ## ?
  3. Lazy Rat

    Integration problem using u substitution

    Im sorry fresh_42 I am finding difficult to follow that logic. Are you asking what i would get for the constant?
  4. Lazy Rat

    Integration problem using u substitution

    Homework Statement ## \int {sin} \frac{\pi x} {L} dx ##Homework Equations u substitution The Attempt at a Solution If i make ## u = \frac{\pi x} {L} ## and then derive u I get ## \frac {\pi}{L} ## yet the final solution has ## \frac {L}{\pi} ## The final solution is ## \frac {L}{\pi} - cos...
  5. Lazy Rat

    Eigenfunction energy levels in a harmonic well

    So would i use the fact that ## E_1 = \frac {3}{2} \hbar ω_0 ## which would give ## e^ \frac {- 3iω_0t}{2} ## And ## E_3 = \frac {7}{2} \hbar ω_0 ## which would give ## e^ \frac {- 7iω_0t}{2} ## Am I on the right track?
  6. Lazy Rat

    Eigenfunction energy levels in a harmonic well

    the specific question goes as so For this equation ## \Psi (x,0) = \frac {1}{\sqrt{2}}(\psi_1 (x)-\psi_3 (x)) ## The system is undisturbed, obtain an expression for ##\psi (x,t)## that is valid for all t ≥ 0. Express in terms of the functions ##\psi_1 (x)##, ##\psi_3 (x)## and ##ω_0##, the...
  7. Lazy Rat

    Eigenfunction energy levels in a harmonic well

    Homework Statement If the first two energy eigenfunctions are ## \psi _0(x) = (\frac {1}{\sqrt \pi a})^ \frac{1}{2} e^\frac{-x^2}{2a^2} ##, ## \psi _1(x) = (\frac {1}{2\sqrt \pi a})^ \frac{1}{2}\frac{2x}{a} e^\frac{-x^2}{2a^2} ## Homework EquationsThe Attempt at a Solution Would it then be...
  8. Lazy Rat

    Integration of an equation relating to electrostatics

    Ah yes of course the dr, by clean up the left side you mean don't have the ## \frac d {dr} ## in the equation? Thanks rude man
  9. Lazy Rat

    Integration of an equation relating to electrostatics

    Ok thanks for clearing up confusion guys I think I may have got there, I have after multiplying out ## ∫ \frac d {dr}( r \frac {dV}{dr}) = ∫ - \frac ρ ε {r} ## Integrating twice ## v(r) = A ~ ln (r) - \frac {ρ r^2} {4 ε} + B ## Is this correct? Thank you
  10. Lazy Rat

    Integration of an equation relating to electrostatics

    I see, I've epand the brackets not multiplied out. ## \frac d{dr} (r \frac {dV}{dr})= \frac {\rho f} {\epsilon \epsilon_0} r## Is this correct? Can the derivative terms such as ## \frac d{dr} ## be manipulated algebraically, and why is it ## \frac d{dr} ## and not ## \frac {dV}{dr} ## are these...
  11. Lazy Rat

    Integration of an equation relating to electrostatics

    Hi Ok so first step is to multiply out. Thus we have for ## \frac 1r \frac d{dr} (r \frac {dV}{dr})= \frac {\rho f} {\epsilon \epsilon_0} ## ## \frac 1r \times r + \frac 1r \times \frac {dV}{dr} + \frac d{dr} \times r +\frac d{dr} \times \frac {dV}{dr} =\frac {\rho f} {\epsilon \epsilon_0} ##...
  12. Lazy Rat

    Integration of an equation relating to electrostatics

    So I get the same because the right side I treat as a constant. The answer is still the Laplace general solution ##V(r)= A~ ln (r)~ + B## Is this correct? Thank you rude man, may try to tackle in spherical.
  13. Lazy Rat

    Integration of an equation relating to electrostatics

    ##-ρf / εε_0## relates to Poisson equation ##pf## is the free charge density and ##ε_0## is the permitivity of free space. So these can be taken as know constants on this occasion. I am looking to achieve a general solution through integrating twice. With a similar equation for electrostatics...
  14. Lazy Rat

    Integration of an equation relating to electrostatics

    Homework Statement Hi I was wondering if anyone could give me a hand with this problem I'm trying to solve. I am trying to integrate this equation twice. I'm not really sure what to do with the right hand side of the equation.Homework Equations The Attempt at a Solution [/B] The left side...
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