Types of Energy:
- Chemical energy (Food)
- Thermal energy (Heat)
- Kinetic energy (Movement)
- Sound energy
- Light energy
- Gravitational (potential) energy
- Electrical energy
- Geothermal energy (Heat Underground)
- Elastic (potential) energy (Stored in springs e.g clocks)
Energy is not created or destroyed; it can only be transferred from one form to another
Lowest possible temperature - absolute zero = 0 Kelvin
Thermal conduction is the transfer of thermal energy through a substance without the substance itself moving
Convection is the transfer of heat through fluids by the upward movement of warmer, less dense regions of fluid
Thermal radiation is the transfer of energy by infra-red waves
The key to energy efficient is insulation. Houses may be insulated with double-glazed windows or walls with a layer of glass fibre insulating wool which is used to stop convection currents in the air gap.
Work and Power
!ENERGY IS THE ABILITY TO DO WORK!
!WORK DONE IS EQUAL TO THE AMOUNT OF ENERGY TRANSFERRED!
Work done (Wd) = Fd
GPE = mgh
KE = 1/2 mv^2
Work done lifting object = gain in GPE = gain in KE of object just before hitting the ground
Power = Wd/t
Energy Resources and Electricity Generation
Non-renewable energy resources
A non-renewable energy resource is one that effectively cannot be replaced once it has been used
Burning fossil fuels results in the release of carbon dioxide (greenhouse gas) which traps the Sun's rays in the atmosphere causing GLOBAL WARMING.
Advantages - "clean" so no pollution
Disadvantages - power stations are expensive to build, risk of accidents, hard to dispose of once power station is finished
Renewable energy resources
Examples - wood, hydroelectric power [turbines (GPE -> KE)], wind power, solar power