Which two statements are true about a system? A) All systems are made by humans. B) A system is a group of objects analyzed as one unit. C) Energy that moves across system boundaries is conserved. D) There’s only one way to define the boundaries of a system.
The Correct Answer and Explanation is:
The two true statements are:
B) A system is a group of objects analyzed as one unit.
C) Energy that moves across system boundaries is conserved.
Explanation:
- B) A system is a group of objects analyzed as one unit:
In system analysis, a “system” refers to a collection of components or objects that are analyzed together as a single unit. This allows for simplification of complex problems. For instance, in thermodynamics, a system could refer to the gas inside a container, while the container’s walls and the surrounding environment are considered outside the system. The focus is typically on the interactions between the objects within the system and the energy and matter that flow in and out of it. This concept helps to isolate the system from the external world, enabling better study and analysis. - C) Energy that moves across system boundaries is conserved:
According to the law of conservation of energy, energy cannot be created or destroyed, only transferred or transformed. This principle holds true in the context of systems. When energy crosses the boundaries of a system (e.g., heat transferred to or from a gas), the total energy remains constant. The energy entering or leaving a system can take various forms (heat, work, etc.), but the total energy before and after the transfer remains unchanged, as long as no energy is lost to external factors like friction.
Why the other statements are false:
- A) All systems are made by humans:
This statement is false. Not all systems are human-made. Many systems occur naturally in nature. For example, ecosystems, weather systems, and biological systems are natural phenomena, not created by humans. - D) There’s only one way to define the boundaries of a system:
This is also false. The boundaries of a system can be defined in various ways depending on the context and purpose of the analysis. For example, in a mechanical system, boundaries could be defined by the physical walls of the system, while in a thermodynamic system, the boundaries could be based on the flow of energy or mass. The choice of boundaries depends on what aspects of the system are of interest to the study.
