The difference between heat capacity at constant pressure and heat capacity at constant volume is inversely proportional to its isothermal form, while for a gas, its adiabatic form is given by the adiabatic index times the pressure.
In the isentropic response of an isotropic material, the fractional change in this quantity is typically less than one percent. In solids, the square of this quantity plus four thirds eta over the density gives the speed of sound in that medium, while in liquids the addition of eta is omitted. The difference between heat capacity at constant pressure and heat capacity at constant volume is inversely proportional to its isothermal form, while for a gas, its adiabatic form is given by the adiabatic index times the pressure. Derivable from the trace of the strain tensor, for ten points, identify this elastic constant which is proportional to the change in pressure over the change in volume and is the inverse of compressibility.
In the isentropic response of an isotropic material, the fractional change in this quantity is typically less than one percent.
bulk modulus