In thermodynamics, what is the relationship between energy and work according to the First Law?

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. This law emphasizes the conservation of energy in a closed system. The principle directly links energy, work, and heat, indicating that the total energy of a system is constant, and any change in the internal energy of the system is equal to the amount of energy added to the system as heat minus the work done by the system on its surroundings.

In this context, the assertion that energy equals work done reflects a part of this relationship, particularly in scenarios where work is the only form of energy transfer occurring. When work is done on a system, it increases the system's internal energy, while work done by the system decreases it. This concise relationship is essential in understanding how systems operate under thermodynamic principles.