Closed Systems and Isolated Systems

In summary, within the scope of classical mechanics, there is a distinction between open and closed systems, but not between closed and isolated systems. In thermodynamics, the concept of an isolated system corresponds to that of a closed system in classical mechanics. The law of conservation of momentum applies to all interactions involving matter in both open and closed systems.
  • #1
PFuser1232
479
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Within the scope of classical mechanics, what exactly is the definition of a closed system, and of an isolated system? Also, do these definitions differ in thermodynamics?
And does the law of conservation of linear momentum apply to a closed system or an isolated system?
 
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  • #2
MohammedRady97 said:
Within the scope of classical mechanics, what exactly is the definition of a closed system, and of an isolated system? Also, do these definitions differ in thermodynamics?
And does the law of conservation of linear momentum apply to a closed system or an isolated system?
In thermodynamics, the distinction between closed systems and open systems is whether the system can lose or gain matter. Closed systems can't. Open systems can.

The law of conservation of momentum is a fundamental physical law that applies to every interaction involving matter. There is no distinction between open and closed systems relating to the applicability of this law. The only thing that matters is the interaction. The momentum of all the interacting bodies before the interaction must be equal to the momentum of all the interacting bodies after the interaction. One has to include the momentum of massless particles as well (photons).

AM
 
  • #3
Andrew Mason said:
In thermodynamics, the distinction between closed systems and open systems is whether the system can lose or gain matter. Closed systems can't. Open systems can.

The law of conservation of momentum is a fundamental physical law that applies to every interaction involving matter. There is no distinction between open and closed systems relating to the applicability of this law. The only thing that matters is the interaction. The momentum of all the interacting bodies before the interaction must be equal to the momentum of all the interacting bodies after the interaction. One has to include the momentum of massless particles as well (photons).

AM

Yes, I am familiar with the idea that momentum is always conserved, regardless of whether or not the system under study is closed/isolated. Perhaps I should've made my question more clear: which statement is correct?
1) The total momentum of a closed system remains constant.
Or
2) The total momentum of an isolated system remains constant.
 
  • #4
MohammedRady97 said:
Yes, I am familiar with the idea that momentum is always conserved, regardless of whether or not the system under study is closed/isolated. Perhaps I should've made my question more clear: which statement is correct?
1) The total momentum of a closed system remains constant.
Or
2) The total momentum of an isolated system remains constant.

The second one.
 
  • #5
MohammedRady97 said:
Within the scope of classical mechanics, what exactly is the definition of a closed system, and of an isolated system? Also, do these definitions differ in thermodynamics?

Classical mechanics doesn't have a concept of an isolated system. Systems are open or closed in classical mechanics. The thermodynamics concept of an isolated system corresponds to the classical mechanics concept of a closed system. A closed system in thermodynamics is an open system in classical mechanics.
 
  • #6
I thought you meant "isolated" as a system that does not interact with any other system (in this case, the total momentum vector of the system remains constant).
 

1. What is a closed system?

A closed system is a physical system in which no matter can enter or leave, but energy can be exchanged with the surroundings. This means that the total amount of matter within the system remains constant.

2. What is an isolated system?

An isolated system is a physical system in which neither matter nor energy can be exchanged with the surroundings. This means that the system is completely self-contained and its total energy remains constant.

3. What is the difference between a closed system and an isolated system?

The main difference between a closed system and an isolated system is the exchange of energy with the surroundings. In a closed system, energy can be exchanged, but not matter, while in an isolated system, neither matter nor energy can be exchanged.

4. What are some examples of closed systems?

Some examples of closed systems include a sealed jar, a closed thermos, and a sealed greenhouse. In each of these systems, matter cannot enter or leave, but energy can be exchanged with the surrounding environment.

5. How do closed and isolated systems relate to the laws of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted. Closed and isolated systems both adhere to this law, as the total energy within these systems remains constant. Additionally, the second law of thermodynamics states that in a closed system, the total entropy (measure of disorder) cannot decrease. This means that in a closed system, energy will always tend to disperse and become less organized over time.

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