Which law states energy cannot be changed without loss of usable energy?

Which law states energy cannot be changed without loss of usable energy?

• A. First Law of Thermodynamics
• B. Second Law of Thermodynamics
• C. Entropy
• D. Metabolism

Answer: (B)

Energy transformations can’t be perfectly efficient because some energy always becomes less usable, typically as heat. This idea is captured by the Second Law of Thermodynamics, which says that in any real process, entropy increases and energy disperses, so not all of it can do work. In other words, you can transform energy, but you pay a price in terms of lost usable energy as the system moves toward greater disorder. The First Law, by contrast, is about energy conservation—total energy stays the same, even though its form changes. Entropy is a measure of energy dispersal and disorder that reflects the second law, but it isn’t itself a standalone law. Metabolism refers to the chemical reactions in living organisms, not a thermodynamic law.

Energy transformations can’t be perfectly efficient because some energy always becomes less usable, typically as heat. This idea is captured by the Second Law of Thermodynamics, which says that in any real process, entropy increases and energy disperses, so not all of it can do work. In other words, you can transform energy, but you pay a price in terms of lost usable energy as the system moves toward greater disorder. The First Law, by contrast, is about energy conservation—total energy stays the same, even though its form changes. Entropy is a measure of energy dispersal and disorder that reflects the second law, but it isn’t itself a standalone law. Metabolism refers to the chemical reactions in living organisms, not a thermodynamic law.