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Topic 1 Energy By Bethan Poole (1.1 Energy changes in a system and the…
Topic 1 Energy
By Bethan Poole
1.1 Energy changes in a system and the ways energy is stored before and after such changes
1.1.2 Changes in Energy
Kinetic Energy
Of a moving object
Elastic Potential Energy
Stored in a stretched or compressed string
GPE
Gained by raising an object above ground level
1.1.3 Energy changes in systems
The amount of energy stored in or released from a system as its temperature changes
1.1.1 Energy Stores and Systems
System
- An object or group of objects
When a system changes there are changes in the way the energy is stored
i.e
When an object is projected upwards
A moving object hitting an obstacle
An object accelerated by a constant force
A vehicle slowing down
Bringing water to a boil in an electric kettle
1.1.4 Power
Defined as the rate at which energy is transferred or the rate at which work is done
1.2 Conservation and dissipation of energy
1.2.1 Energy transfers in a system
Energy can be transferred usefully, stored or dissipated
Energy can't be created or destroyed
In a closed system the total energy never changes but it can be transferred form one store to another
Wasted energy is caused by unwanted energy transfers
These unwanted transfers can be reduced in several ways:
Tightening any loose parts- prevents unwanted vibrationthat wastes energy as sound
Thermal insulation- reduces heat loss
Lubrication- reduces the friction that produces heat
A building wastes energy when it loses heat to the surroundings
The rate of cooling depends on the thickness and thermal conductivity of the walls- thin walls with high thermal conductivity with conduct heat the quickest and the building will cool down rapidly
1.2.2 Efficiency
To increase the efficiency of an energy transfer, the amount of wasted energy needs to be reduced
1.3 National and global energy resources
1.3 National and global energy resources
Main uses for energy resources are transport, electricity generation and heating
Renewable
They can be replenished
Non-Renewable
They will eventually runout
Renewable
Biofuel
Uses
Transport and electricity generation
Enviromental impacts, ethics, reliability and other info
Large areas of land needed for growing fuel crops. Can be at the expense of food crops in poorer countries
Wind
Uses
Electricity generation
Enviromental impacts, ethics, reliability and other info
Does not provide a constant source of energy. Turbines can be noisy/ dangerous to birds. Some think they ruin the apperance of the countryside
Water (hydro-electricity)
Uses
Electricity Generation
Enviromental impacts, ethics, reliability and other info
Requires large areas of land to be flooded, altering the ecosystem and displacing the people who live there
Geothermal
Uses
Electricity generation and heating
Enviromental impacts, ethics, reliability and other info
Only available in a limited number of places where hot rocks can be found close to the surface e.g. Iceland
Solar
Uses
Electricity generation and some heating
Enviromental impacts, ethics, reliability and other info
Depends on light intensity, so no power produced at night. High cost in relation to power output
Water Waves
Uses
Electricity generation
Enviromental impacts, ethics, reliability and other info
Output depends on waves so can be unreliable. Can alter habitats
Tidal
Uses
Electricity generation
Enviromental impacts, ethics, reliability and other info
Variations in tides affect output. Have a high inital set-up cost. Can alter habitats/cause problems for shipping
Non-renewable
Coal
Uses
Electricity generation, heating and some transport
Enviromental impacts, ethics, reliability and other info
Burning produces greenhouse gases (CO2) and contributes to acid rain (SO2). Reliable output
Oil
Uses
Transport and heating
Enviromental impacts, ethics, reliability and other info
Reliable output. Provies a compact source of energy for transport. Burning CO2, NO2 and SO2. Serious enviromental damage if split
Nuclear Fuel
Uses
Electricty generation and some military transport
Enviromental impacts, ethics, reliability and other info
Produces radioactive waste but no other emmissions. Costly to build and decommission. Reliable output
Gas
Uses
Electricity generation, heating and some transport
Reliable output. Burning produces CO2 but not SO2