You're on a roll — The First Law of Thermodynamics is a statement of the conservation of energy. It states that the change in the internal energy of a system ($\Delta U$) is equal to the heat added to the system ($Q$) minus the work done by the system ($W$). Mathematically, it is expressed as: $$ \boxed{\Delta U = Q - W} $$ Here: • $\Delta U$ represents the change in the internal energy of the system. Internal energy is the total energy contained within a thermodynamic system, including the kinetic and potential energies of its molecules. • $Q$ represents the heat added to the system. If heat is removed from the system, $Q$ is negative. • $W$ represents the work done by the system. If work is done on the system, $W$ is negative (or the equation can be written as $\Delta U = Q + W_{on}$, where $W_{on}$ is work done on the system). This law implies that energy cannot be created or destroyed, only transferred or converted from one form to another. What's next? Send 'em.