What is the solution for a fixed string oscillating at both ends?

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The discussion revolves around solving the wave equation for a fixed string oscillating at both ends, described by the equation ∂²Ψ/∂t² = ∂²ψ/∂x². The initial conditions specify the displacement of the string at t=0, with different expressions for two segments of the string's length. Participants discuss the method of separation of variables as a technique to solve the partial differential equation, emphasizing the need to rearrange the equation to isolate variables. The goal is to derive the solution for the displacement of the string over time, ultimately leading to a series solution involving sine and cosine functions. The conversation highlights the mathematical approach required to tackle this problem effectively.
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This isn't actually a homework or coursework problem, but the style of the question is similar so I'm posting it here. Anyways, here goes. Consider a string of length L clamped at both ends, with one end at x=0 and the other at x=L. The displacement of the oscillating string can be described by the following equation:
\frac{\partial^2 \Psi}{\partial t^2}=\frac{\partial^2 \psi}{\partial x^2}

<br /> \textrm{Given that at t=0:}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,0)=\frac{2xh}{L},0\leq x\leq \frac{L}{2}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,0)=\frac{2xh}{L},(L-x),\frac{L}{2}\leq x\leq L\\<br /> \textrm{Show:}\\<br /> \&gt;\&gt;\&gt;\&gt; \psi(x,t)=\sum_{m=1}^\infty\sin\left(\frac{m\pi x}{L}\right)\cdot\cos\omega_mt\cdot\left(\frac{8h}{\pi^2m^2}\right)\cdot\sin\left(\frac{\pi m}{2}\right)<br />

So, how do we go about doing that?
 
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Do you know the method of separation of variables?
 
haruspex said:
Do you know the method of separation of variables?

Yeah, that's just rearranging the equation so that different variables occur on opposite sides of the equation. You can also do this by defining a variable as some expression, substitute, and the separate them.
 
So what does that give you for generic solutions of the PDE?
 
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