Which law establishes energy cannot be created or destroyed and the energy balance includes energy in, energy out, and energy storage?

Which law establishes energy cannot be created or destroyed and the energy balance includes energy in, energy out, and energy storage?

• A. Zeroth Law
• B. First Law
• C. Second Law
• D. Third Law

Answer: (B)

The main idea is the conservation of energy: energy cannot be created or destroyed, only transformed or transferred. In engineering terms, the energy balance for a system says that energy entering the system plus any internal generation minus energy leaving must equal the change in the system’s stored energy. This can be written as Ein − Eout = ΔEstorage, and in steady state the storage term is zero, so Ein ≈ Eout. This principle is what the First Law of Thermodynamics expresses, and it’s the foundation for analyzing heat transfer and fluid flow. The other laws describe different concepts: the Zeroth Law is about thermal equilibrium between bodies, the Second Law concerns entropy and the direction of natural processes, and the Third Law deals with entropy approaching a constant value at absolute zero.

The main idea is the conservation of energy: energy cannot be created or destroyed, only transformed or transferred. In engineering terms, the energy balance for a system says that energy entering the system plus any internal generation minus energy leaving must equal the change in the system’s stored energy. This can be written as Ein − Eout = ΔEstorage, and in steady state the storage term is zero, so Ein ≈ Eout. This principle is what the First Law of Thermodynamics expresses, and it’s the foundation for analyzing heat transfer and fluid flow.

The other laws describe different concepts: the Zeroth Law is about thermal equilibrium between bodies, the Second Law concerns entropy and the direction of natural processes, and the Third Law deals with entropy approaching a constant value at absolute zero.