practice9-q6

Today we’re going to discuss systems. What is a system? you might be asking. Well, picture a few items interacting with one another. Anytime two or more elements interact with one another, you have a system. There are two general kinds of systems that exist in nature: closed and open.

In a closed system, the items that are interacting with one another interact with nothing else; that is, a closed system exchanges neither mass nor energy with its environment. It is completely isolated. So, when the energy within the system is used up, the interactions will stop. This occurs because a closed system does not take in any energy from its surroundings. One example that may help illustrate this idea is that of a watch. Within a watch you have items interacting with one another: gears, the battery, and other elements. This makes the watch a system. But, this system does not exchange anything with its surroundings: no mass or energy passes between the watch and its environment, which makes the watch a closed system. And, like all other closed systems, because our watch does not take in any energy from the environment, the process occurring within it will eventually stop. That’s why, when the battery dies in a watch, the watch stops.

An open system, on the other hand, interacts, well. . . openly with its environment. It freely exchanges both mass and energy with its surroundings. Generally speaking, an open system can go on and on, unlike a closed system, since it can be continually re-supplied with energy from its environment. Humans are perfect examples of open systems. We exchange mass with our surroundings. For example, we take in oxygen, and we release carbon dioxide. And, we exchange energy with our surroundings: we absorb energy from the sun and we release energy as body heat. Technically speaking, there’s no reason for the processes within us to stop, since we can be continually supplied with energy from our environment.