By closed system, I mean anything which you can isolate from anything else.
For example, a car and a truck are both vehicles, but a vehicle is neither a car or a truck.
The truck or car are the subject/closed system.
For example, a car and a truck are both vehicles, but a vehicle is neither a car or a truck.
The truck or car are the subject/closed system.
In that line, what do you define as a "closed system"? Technically, nothing exists that doesn't somehow interact with its surroundings. Including humans (we breath, eat, absorb/exchange heat from air/sun, etc). Also black holes (Hawking radiation).