Open, closed and isolated systems
An open system exchanges both energy and matter across its boundary. A closed system exchanges only energy. Watch the counter: in a closed system the matter inside never changes, and the energy arrows never stop.
energy inenergy outmatter crosses the boundarythe system boundary
Matter inside
10particles, changing
Energy
in and out
Matter
in and out
Try a real system
Whether something is open or closed depends on where you draw the boundary, not on what it is made of.
What to notice
- Switch to Closed and the energy arrows keep flowing. A closed system is not a sealed, inert box.
- In Closed the matter counter stops moving, because the particles outside can no longer get in and the ones inside can no longer leave.
- Isolated is not on the syllabus. It is here because it is what a closed system gets confused with, and because nothing on Earth is one.