The First Law of Thermodynamics is a statement of which principle?
A The efficiency of heat engines.
B Entropy always increases in an isolated system.
C Energy cannot be created or destroyed, only transformed or transferred.
D Heat naturally flows from hot to cold objects.
The correct answer and explanation is:
The correct answer is C: Energy cannot be created or destroyed, only transformed or transferred.
The First Law of Thermodynamics, often referred to as the Law of Energy Conservation, states that the total energy of an isolated system remains constant. This law essentially means that energy can neither be created nor destroyed. Instead, it can only be transformed from one form to another, or transferred between systems. For example, when you burn fuel, the chemical energy stored in the fuel is converted into heat energy, and in some cases, mechanical energy, like in an engine.
This principle is foundational in thermodynamics and plays a significant role in understanding how energy is conserved in physical processes. One of the core applications of this law is in the analysis of heat engines. In such systems, fuel is burned to produce heat, which is then used to perform mechanical work, and the energy is conserved throughout the process.
The First Law has far-reaching implications. For example, in electrical circuits, electrical energy can be converted into light, heat, or mechanical energy, but the total amount of energy remains unchanged. In biological systems, chemical energy in food is transformed into kinetic energy for movement or heat for maintaining body temperature.
The First Law does not, however, provide information on the direction of energy transformations or the quality of energy changes. It does not indicate whether the energy conversion is efficient or how energy spreads out. These aspects are covered by the Second Law of Thermodynamics, which addresses the concept of entropy and how energy tends to disperse in a system.
In summary, the First Law of Thermodynamics emphasizes energy conservation, noting that energy can only change forms or move between systems, but it cannot vanish or be created anew.