Non-uniform thermal conductivity

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Homework Help Overview

The discussion revolves around a differential equation involving non-uniform thermal conductivity, where the thermal conductivity \( k \) is defined as a linear function of temperature. The original poster is attempting to solve the equation \( \frac{d}{dx}(k \frac{dT}{dx}) = 0 \) and is exploring the implications of this equation in the context of thermal conduction.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to manipulate the equation to facilitate integration, expressing concerns about the presence of the term \( k(0) \) in their solution. Other participants engage by discussing the implications of derivatives being equal to zero and the nature of constants in the context of the problem.

Discussion Status

The discussion is active, with participants providing insights into the implications of the equations. Some guidance has been offered regarding the integration process, and there appears to be a productive exchange of ideas about handling the variable \( k \) as a function of temperature.

Contextual Notes

Participants are navigating the complexities introduced by the linear dependence of \( k \) on temperature, which adds a layer of difficulty to the integration process. There is an acknowledgment of constraints related to the expected form of the final answer.

matt222
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Homework Statement



solve d/dx(kdT/dx)=0
where k is linear function of temperature
k=k(0)(1+BT)

Homework Equations



this is the solution

T+BT^2/2=Ax+C

The Attempt at a Solution



i opened the equation so that it becomes equal to

dk/dx*dT/dx+kd^2T/dx^2=0

i subtitute the value of K in the equation and tried to integrate it but i relize that i am not doing it in a correct way, can you giude me please
 
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If
[tex]\frac{d f(x)}{d x} = 0[/tex]
then what does this say about f(x)?
 
f(x) is constant
 
the problem now we have another variable which is K which is a linear function of T , i need to integrate this but i need a giude i did it but i have a term of k(0) which is not accepted as the final answer said
 
it is ok if i need to integrate df(x)/dx=0, so f(x)=A

same with d^2f(x)/dx=0

f(x)=Ax+B

but the problem here with the another term which is K as a linear of temperature
 
So you have:

d/dx(kdT/dx)=0

which implies that:

kdT/dx) = const

Substituting for k:

k0(1+BT) dT/dx = const

(1+BT) dT = (const/k0)*dx

(1+BT) dT = A*dx letting A = const/k0
 
thats it , many thanks got it
 

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