4. A hollow cylinder of inner radius $r_1$, outer radius $r_2$ and length $L$ generates heat at a rate $q'''$.
The inside surface is insulated, and the outside surface is maintained at a uniform temperature $T_o$.
Assume steady state one-dimensional heat flow.
[a] Using conservation of energy at the outer surface, derive an expression for the heat transfer
coefficient for an ambient temperature $T_\infty$.
[b] Write the heat conduction equation and boundary conditions.
[c] Determine the temperature distribution $T(r)$.