Example 11.1-3. Cooling of a Sphere in Contact with a Well-Stirred Fluid
"A homogeneous sphere of solid material, initially at a uniform temperature T1, is suddenly immersed in a volume Vf of well-stirred fluid of temperature T0 in an insulated tank. It is desired to be able to find the thermal diffusivity of the solid ... by observing the change of fluid temperature Tf with time."
In order to find the temperature profile of the fluid over time without finding the temperature profile in the solid, a Laplace transform is used.