Thermodynamics adds a new quantity, called internal energy, into the fold; it’s the energy possessed by the system itself. Getty Images. If we add heat to the system, its internal energy increases.

For an Ideal Gas, the internal energy is only a function of the gas temperature and is a measure of the mean translational kinetic energy of the gas atoms. These atoms have three translational degrees ...

"The First Law says that the internal energy of a system has to be equal to the work that is being done on the system, plus or minus the heat that flows in or out of the system and any other work ...

Thermal energy is the total energy an object has due to the internal motions of its particles. The temperature is related to the average kinetic energy—not the total kinetic energy.