Answer:
Energy conservation.
Explanation:
The 1st Law of Thermodynamics is a statement about energy conservation. It states that [tex]\Delta U=Q-W[/tex], which means that if we substract the work W done by the system to the heat Q given to the system we get the change in the internal energy [tex]\Delta U[/tex], so any excess in energy given to the system appears as internal energy, stating that energy is conserved.
