Section D: Energy Resources and Energy Transfers

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

Conduction

Thermal conduction is the transfer of thermal energy through a substance without the substance itself moving

Convection

Convection is the transfer of heat through fluids by the upward movement of warmer, less dense regions of fluid

Radiation

Thermal radiation is the transfer of energy by infra-red waves

Energy-Efficient houses

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.

!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

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.

Nuclear fuel

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