2
$\begingroup$

there we have the EOM: \begin{align*} \alpha q_{2} + \lambda - \ddot{q}_1=0 \\ \alpha q_{1} + \lambda - \ddot{q}_2=0 \end{align*}

and $q_{i}$ is the canonical coordinates. Can I use the Fourier transform to solve it? and how?

I want to solve the EOM like the coupled Hamonic oscillators by using Fourier transform like

$$q_{i} (t) =\frac{1}{\sqrt{N}}\int \tilde{q}_{i}(\omega)e^{i \omega t}d \omega $$ and $$ -\frac{1}{\sqrt{N}}\int \omega^{2}\tilde{q}_{1}(\omega)e^{-i \omega t}d \omega = \alpha \frac{1}{\sqrt{N}}\int \tilde{q}_{2}(\omega')e^{i \omega^{'} t}d \omega^{'} + \lambda.$$ $$ -\frac{1}{\sqrt{N}}\int {\omega^{\prime}}^{2} \tilde{q}_{2}(\omega^{'})e^{-i \omega^{\prime} t}d \omega^{\prime} = \alpha \frac{1}{\sqrt{N}}\int \tilde{q}_{1}(\omega)e^{i \omega t}d \omega + \lambda.$$ How to solve this equation?

$\endgroup$
4
  • $\begingroup$ Hello and welcome to Physics SE. It is not customary to solve homework-like problems for you here. You should at least provide some of your work. What have you tried, where and how did you fail, what is that you don’t understand, what does not make sense to you and which approaches did you try? Things such as that will show to people that you have tried to solve the problem yourself and will also help them to provide spot-on help focusing on the problem at hand and not generic possible solutions that may or may not work. $\endgroup$
    – ZaellixA
    Commented Mar 10 at 9:29
  • 1
    $\begingroup$ Thank you. I was trying to use Fourier transform to solve it but failed while using Dirac delta function. Let me add some work in the question. $\endgroup$
    – Qian-Sheng
    Commented Mar 10 at 9:32
  • 2
    $\begingroup$ Taking the twice the derivative of the first equation and using then the second equation gives you $q_1^{(4)}=\alpha q_2^{(2)}=\alpha(\lambda+\alpha q_1)=\alpha \lambda + \alpha^2q_1$. $\endgroup$ Commented Mar 10 at 9:38
  • 5
    $\begingroup$ Hint: Look at sum and difference. $\endgroup$
    – Qmechanic
    Commented Mar 10 at 11:08

0