What does the First Law of Thermodynamics state?

The First Law of Thermodynamics, also known as the Law of Energy Conservation, states that energy can only be transformed from one form to another and cannot be created or destroyed. This principle emphasizes that the total amount of energy in a closed system remains constant, although it may change from one type to another—such as from potential energy to kinetic energy or from thermal energy to mechanical energy. This understanding is foundational in thermodynamics and helps in analyzing energy transfer in various physical systems, engineering environments, and industrial applications.

In contrast, the other choices do not accurately reflect this law. The notion that energy can be created and destroyed is specifically contradicted by the First Law. The assertion about energy being constant in an isolated system is not the primary focus of the law, though it does touch on the concept of conservation. Lastly, the idea that energy increases in a closed system misrepresents the principle, as it suggests an accumulation of energy rather than a transformation between forms.