## 32 Interim Conclusions

According to the previous considerations, the following quantities are invariant in the sense of STR :

- pressure
*P*n( and pressure changes ) - particle number
*N*jand amount of substance*n*j=*N*/*N*_{A} - thermodynamic efficiency as a quotient of temperatures

The following quantities are transformed by multiplication by the root factor:

- volume
*V*j( and volume changes ) - mean particle velocity
*u* - average kinetic energy of the particles
- the products
*k·T*nand*R·T* - heat quantities
*Q*j - internal energy
*U*j - thermodynamic workj
*P · V* - enthalpy
*H*

The following values are transformed by dividing by the root factor:

- total energy
*j**E*j - particle density

There is no simple transformation in the sense of section **2** for the following process variable:

- performed work j
*W*

The following laws continue to apply *mutatis mutandis* for all inertial observers:

- the first law of thermodynamics
- the second law of thermodynamics
- the ideal gas law mmmmm
*P · V*j=*n · R · T*=*N · k · T* - the relation mmmmmimmmm d
*S*= d*Q*/*T*

For non-relativistic ideal gases we further have the invariant relationships

**Up to now** we did not use the final result of the first part of this treatise:

*T'* = *T*

Combining the invariance of temperature with the results of sections **22** to **30** will yield a quite simple final statement: **All** important equations of thermodynamics are invariant in the sense of STR !