According to the first law of thermodynamics, what is true about energy?

The first law of thermodynamics, often referred to as the law of energy conservation, states that energy cannot be created or destroyed, only transformed from one form to another. This principle implies that the total amount of energy in an isolated system remains constant over time. For instance, when energy changes form, such as when chemical energy in fuel is converted into thermal energy during combustion, the overall quantity of energy remains unchanged, even though it appears in different forms.

This law is foundational in understanding various processes in physics, chemistry, and engineering. It means that while energy can change from kinetic to potential energy or be transferred between systems, the total amount of energy involved in a closed system remains stable. Thus, the notion that energy cannot be created or destroyed but can be transformed underscores the efficiency and limitations of energy use in practical applications.