Systems

Systems, Topic 1

System - collection of parts working together, forming a functioning whole.

Three types of systems
Open System - exchanges matter and energy with its surroundings, ex. Ecosystem * energy from sun, converted to sugar by plant, plant is eaten by a bug - energy exchange * animals eating each other - matter exchange
Closed system - exchanges energy with its surroundings but not matter, ex. Biosphere 2 experiment * closed systems do not occur naturally, unless the whole of earth itself is considered a system.
Isolated system - neither matter or energy is exchanged, no such systems exist, possible exception of the universe.

Open systems - Steady State * fluctuation around an average * all ecosystems are open systems
Static equilibrium * most non living stationary systems, ex. a rock

Energy Transfers - Energy is always lost to the environment as heat during an energy transfer — second law of dynamics - a system entropy not at equilibrium tends to increase over time.
Negative feedback * Negative feedback tends to damp down, neutralise, or counteract any deviation from equilibrium, and it stabilises systems or results in steady — state equilibrium.
Positive feedback * Positive feedback results in further increase or decrease within a system. Positive feedback enhances change in a system and it is destabilized and pushed to a new state of equilibrium. Positive feedback results in a ‘vicious circle.’ If a statement contains the word 'more' or 'continuous' it is positive feedback


All ecosystems are open systems
Example:

System - Burning Candle
Inputs - Heat, Oxygen
Outputs - Heat, Light, Smoke
Energy and Material Transfers - energy moves through a system - heat energy is moved/transferred from the candle to the surroundings
Energy and Material Transformations - energy is transformed into new/different types of energy - Chemical energy in the candle is transformed into heat and light energy. · Matter to matter … (soluble glucose converted to insoluble starch in plants)
· Energy to energy … (light converted to heat by radiating surfaces)
· Matter to energy … (burning fossil fuels)
· Energy to matter … (photosynthesis) Stability - If a system is complex the more likely it is that there is a second route than can be taken if one ceases to exist, therefore it is left likely to shut down
Systems diagrams - Exchange of matter = boxes, Exchange of energy = arrows

System models * makes complex things easier to understand * make predicting patterns of systems easier * although the lack complexity of real systems * Kinds: * Physical models * software models * equations * diagrams

James Lovelock * Created the Gaia theory - earth is like a big living organism which responds to what we do to it. instrumental in creating the mechanism that checked for floral carbons in the atmosphere and detect damage in the atmosphere