Internal energy refers to the total amount of kinetic and potential energies possessed by all molecules within a substance. It includes both microscopic motion (kinetic) and forces between molecules (potential).
Related terms
Temperature: Temperature is a measure of average kinetic energy within a substance. It indicates how fast molecules are moving on average.
Thermal equilibrium occurs when two objects or systems reach the same temperature and there is no net flow of thermal energy between them.
Specific Heat Capacity: Specific heat capacity is the amount of heat energy required to raise the temperature of a substance by a certain amount. It is a property that depends on the type of material.