Question

Sometimes the specific heat capacity is described as the thermal inertia of a substance. What does this mean in general terms?

Answer 1

Thermal Inertia by definition refers to the rate at which a given object (or system) absorbs or releases thermal energy to its environment (or surroundings) to achieve equilibrium with that environment. In this case Specific Heat (where I assume you mean Specific Heat Capacity) appears to be a factor in determining the thermal inertia of an object.

This is because specific heat capacity happens to be the amount of thermal energy (heat energy or heat) required to change the temperature of one gram of a substance (or object or system) by one Kelvin (or Celsius). Therefore the magnitude of the specific heat capacity (whether, relatively speaking big or small) will play a factor in determining the rate at which the temperature of the object changes in relation to its environment to achieve equilibrium with the environment(thermal inertia)