System, Surroundings, Boundary, & Closed Systems

A fixed amount of mass. No mass can cross the boundary of the system.

The fluid within the cylinder of a piston-and-cylinder device is an example of a closed system with a moving boundary.

The system boundary is indicated on the diagram by the dashed, black line.

Closed Systems

Open Systems

Types of Systems:
Closed System -
a quantity of mass or a volume of space that
we have chosen to study and the surroundings are everything else in the universe. The system boundary separates the system from the surroundings.
System -

Piston and cylinder

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Ch 1, Lesson C, Page 2 - System, Surroundings, Boundary, & Closed Systems