How is thermal inertia best defined?

Thermal inertia is best defined as the ability of materials to resist temperature change. This concept encompasses how quickly or slowly a material can change temperature in response to external heat sources or changes in temperature. Materials with high thermal inertia are able to absorb and retain heat, which allows them to experience gradual temperature changes, rather than reacting instantly to changes in their environment.

In the context of fire and explosion investigations, understanding thermal inertia is crucial because it influences how materials behave under heat exposure, including their ignition points and how heat might spread within a structure. For example, materials with low thermal inertia may heat up quickly and ignite more easily, while those with high thermal inertia might delay ignition, thus affecting fire dynamics and potential outcomes of fire scenarios.

The other definitions relate to specific aspects of heat and temperature interactions but do not fully capture the broader concept that thermal inertia addresses, which is the overall resistance to a change in temperature over time.