What is a primary component that determines thermal inertia?

Heat capacity is indeed a primary component that determines thermal inertia. Thermal inertia refers to the ability of a material to conduct and retain heat. It reflects how quickly a material can change its temperature when subjected to a heat source or sink.

Heat capacity is a measure of the amount of heat energy required to change the temperature of a unit mass of a substance by one degree Celsius. Materials with high heat capacity can absorb a lot of heat without significant changes in temperature, leading to greater thermal inertia. This property is especially important in fire and explosion investigations, as it affects how materials respond to heat and fire exposure.

In contrast, thermal expansion refers to the change in size or volume of a material in response to temperature changes and does not directly relate to how much heat a material can store or retain. Combustion rate pertains to how quickly a material burns, and smoke density relates to the characteristics of smoke produced during combustion. While all these factors are relevant in fire investigations, they do not directly influence thermal inertia in the way that heat capacity does.