What happens to heat in a thermal system according to the first law of thermodynamics?

According to the first law of thermodynamics, energy cannot be created or destroyed; it can only be transformed from one form to another. This principle is encapsulated in the idea that heat in a thermal system is conserved and transformed. In practical terms, this means when heat is added to a system, it can be converted into other forms of energy such as work. For example, in a heating system, the thermal energy generated can be used to increase the temperature of air, or in a steam engine, heat can convert water into steam to perform mechanical work.

This law emphasizes the conservation of energy within closed systems, ensuring that any energy entering or leaving the system accounts for changes in the internal energy of that system. Thus, the understanding that heat is conserved and transformed aligns perfectly with the foundational concepts of thermodynamics.