Systems

Question 1

What is a system?

Answer 1

Any set of interacting components that influence one another by exchanging energy or materials- a series of stores with flows between them

Question 2

What is feedback?

Answer 2

adjustments in input or output rates caused by changes in the system

Question 3

What are positive and negative feedback?

Answer 3

p= amplifies change in system by causing a further increase or decrease
n= resists change by returning to original state or slowing rate of change (stabilise environments)

Question 4

Describe the 2 types of systems

Answer 4

open= receives inputs and transfers outputs of energy or matter across boundaries within it- W&C cycles
closed= transfer of energy but not matter between system and its surroundings- planet earth

Question 5

Describe inputs, outputs and stores

Answer 5

inputs= enter in order to create outputs
outputs= outcomes, may be used in next element of the system or unintended
stores= energy or matter held- not transferred until appropriate processes move them

Question 6

Describe transfers or flows

Answer 6

movement of energy or matter through system- inputs to become outputs

Question 7

what is a steady state?

Answer 7

inputs=outpus

netflux=0

Question 8

Why would a drainage basin be considered a sub system?

Answer 8

inputs=rainfall from atmosphere
outputs= river discharge to ocean, evaporation
storage= surface waters, soil moisture, groundwater

Question 9

What is the mean residence time?

Answer 9

av. time a typical molecule remains in system

=volume of pool/flux

Question 10

What is a flux?

Answer 10

measurement of rate of flow of material between stores

Question 11

What are isolated systems?

Answer 11

no interactions with anything outside system boundary, no input or output of energy or matter (lab experiment)

Question 12

What is a dynamic equilibrium?

Answer 12

tendency towards a natural state of balance

extreme events or human activity could influence balance