Finding a Solution to Wave Problem: Uxx+Utt=0

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The discussion focuses on solving the wave equation Uxx + Utt = 0 with initial conditions U(x,0) = 0 and Ut(x,0) = 1 for 0 ≤ x ≤ 1, and Ut(x,0) = 0 otherwise. The solution can be expressed as U(x,t) = f(x + t) + g(x - t), leading to the conclusion that f(x) = -g(x) due to the initial condition U(x,0) = 0. The derivative Ut(x,t) can be derived as Ut(x,t) = f'(x+t) - g'(x-t), which simplifies to Ut(x,0) = 2f'(x) based on the relationship between f and g. This provides a pathway to integrate and find f.

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Arben
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Hello everybody.

I don't know how to find solution and to draw it for this wave problem:
Uxx+Utt=0
U(x,0)=0
Ut(x,0)=1 a )for 0<=x<=1 and
Ut(x,0)=0 otherwise.
I have to draw the grafic for t=0, 1, 2 for x element from -5 to 5.
 
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Welcome to PF!

Arben said:
Uxx+Utt=0
U(x,0)=0

Hi Arben! Welcome to PF! :smile:

Hint: 0 = (DxDx - DtDt)U

= (Dx + Dt)(Dx - Dt)U.

= Dx+tDx-tU.

Does that help? :smile:
 
In other words, since this is a wave equation with c= 1, any solution can be written in the form U(x,t)= f(x+ t)+ g(x- t) so U(x, 0)= f(x)+ g(x)= 0=> f(x)= -g(x).

Ut(x,t)= f'(x+t)- g'(x-t). Further, since f(x)= -g(x), f'(x)= -g'(x) so Ut(x,0)= f'(x)-g'(x)= 2f'(x). ;Since you are given Ut(x,0) you can integrate to get f.
 

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