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Ratpigeon
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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 general it doesn't exist for η=-1
Homework Equations
The d'alembert solution is
u(x,t)=1/2(α(x+ct)+α(x-ct))+1/2c [itex]\int[/itex]x+ctx-ctβ(y) dy
for x>ct
The Attempt at a Solution
I know that to restrict it to the whole of the x>=0, t>=0 region, I need to use the boundary condition; but I get that
u(0,t)=0 because α and β are odd, which makes α(ct)+(-ct)
and the integral from -ct to ct of β(y) zero; and so u_t(0,t) is zero which is supremely not useful...