The transient, one-dimensional temperature distribution is determined for bodies with internal heat generation and nonlinear boundary condition in the form:
$k·e·gradθ+ε(θn−T0n)$

$+ε1(θ−T0)=0$
Approximate analytical solutions are derived with the aid of Biot’s variational method. The additional boundary condition introduced by Lardner is modified, and this modification makes it possible to solve the problem. The solution has been obtained assuming a parabolic profile of temperature distribution. Formulas are given for plates, cylinders, and spheres. Some results are illustrated with the graphs, and compared with the exact solution for the case of convective heat transfer.
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