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samee
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Homework Statement
A long copper rod with insulated lateral surface has its left end maintained at a temperature of 0C and its right end, at x=2m , maintained at 100C . Determine the temperature T as a function of time and coordinate if the initial condition is given by
T(x,0)={ 100x, 0<x<1
________100, 1<x<2
Homework Equations
So I'm assuming this question is also actually just a diffusion equation or a wave equation, since that's what the rest of our homework was on. Alpha2uxx=ut
and
u(x,t)=X(x)T(t)=(C1coskx+C2sinkx)e-K2alpha2t+C3+C4x
The Attempt at a Solution
I asked another question like this one... So here I have a rod with a temperature difference. These differences are being maintained, so I guess what I'm doing i assuming that it's in equilibrium and the temperature isn't shifting at all. I'm asked for the temperature as a function of time and coordinate, but that doesn't make sense if time isn't a factor. In the initial condition it certainly is not a factor. So I guess I need to set boundary conditions as given?
I know u(x,0)={X(x)100x 0<x<1
_____________X(x)100 1<x<2
and 0<x<2 for the whole problem.
Now, I really need to set my boundary conditions, right? I guess I can say that since the rod is finite, and 0<x<2, anything less than zero or greater than 2 is zero. Therefore;
u(0,t)=0 and u(2,t)=0.
If u(0,t)=(C1)e-K2alpha2t+C3=0
This would mean that C1=0 and C3=0, so
u(x,t)=(C2sinkx)e-K2alpha2t+C4x=X(x)T(t)If u(2,t)=(C2sink2)e-K2alpha2t+C42=0
This would mean that C4=0 as well. Also,
(C2sink2)e-K2alpha2t=0
If C2 IS NOT 0, then sin2k=0, and 2k=npi. Therefore k=npi/2 and...
u(x,t)=C2sin(xnpi/2)e-(npialpha/2)2t
SOOOO! IF I did my boundary conditions right, I can then plug it back into the original equation and get;
u(x,t)={ X(x)=(1/100x)C2sin(xnpi/2)e-(npialpha/2)2t for 0<x<1
________X(x)=(1/100)C2sin(xnpi/2)e-(npialpha/2)2t for 1<x<2NOW what do I do next?
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