Systems

=//Systems//=

Definitions:
In Physics, we have 3 big types of systems: open, closed and isolated systems. A system is usually a collection of matter/energy/information, like a ball rolling down a hill on the surface of the Earth.

Open System - allows matter and energy in and out of the system. A good example of an open system is a plant or animal cell: cell's let matter (food, waste) in and out and they let energy in and out. The classroom is an open system when the door is opened: it allows matter (i.e. people) in and out, and it allows energy (sound, heat) in and out as well.

Closed System- allow energy in and out, but not matter. A classroom with the door closed is a closed system; energy can still get in or out, but matter (people) can't. In reality, most systems we study in Physics are closed.

Isolated System - does not allow energy, matter or information in or out of the system. In reality, there really is no isolated system (except maybe the universe as a whole). We do, however, assume certain systems to be isolated, like a car coming to a stop on a smooth road or a pendulum swinging back and forth. Most of the systems we encounter in P30 are assumed to be isolated.

Applications:
The reason we care about systems in Physics 30 is that momentum is only conserved in an isolated system. If the system is not isolated, we will not have conservation of momentum, and we won't be able to work out our problem. We don't usually encounter problems like this often in class or on the Diploma, but it could come up.

//References//

 * 1) //Collisions in 1D Notes//, Brad Langdale////, (2012),//// []

//Further Reading// > []
 * 1) []