1. Energy

• System


  Either a single object or a group of objects
• Types of system


  • Open system
  • Closed system
• Open system


  Can exchange energy and matter with their surroundings
• Closed system


  Don't let energy or matter in or out
• In a closed system, the total energy remains the same, even though it might change form inside the system
• Energy


  Measured in Joules
• Energy follows the principle of conservation of energy, which tells us energy can not be created or destroyed, only transferred from one store to another
• Energy stores


  • Thermal energy
  • Chemical energy
  • Kinetic energy
  • Gravitational potential energy
  • Elastic potential energy
  • Nuclear energy
  • Magnetic energy
  • Electrostatic energy
• Energy transfer pathways


  • Mechanical work
  • Heating
  • Electric work
  • Radiation
• Kinetic energy


  Energy of moving objects, calculated using the formula: KE = 1/2 mv^2
• Elastic potential energy


  Energy stored in elastic materials when stretched or compressed, calculated using the formula: EPE = 1/2 ke^2
• Gravitational potential energy


  Energy held by an object due to its height in a gravitational field, calculated using the formula: GPE = mgh
• Specific heat capacity is a property that tells us how much heat energy (in joules) is needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius
• Water has a specific heat capacity of 4186 J/kg°C, while oil has a lower specific heat capacity of 1670 J/kg°C
• Thermal energy change


  Calculated using the formula: Q = mcΔT
• This experiment shows you how to measure the specific heat capacity of a substance like aluminium
• Power


  The rate at which energy is being transferred or work is being done, calculated using the formulas: P = E/t or P = W/t
• The principle of conservation of energy states that energy cannot be created or destroyed, only transferred between different energy stores
• Energy dissipation


  Energy that is wasted or not usefully employed by a device
• Ways to reduce unwanted energy transfers


  • Cavity walls
  • Loft insulation
  • Double glazing windows
  • Draught excluders
• Friction converts some of the kinetic energy, which should be moving the bike forward, into thermal energy
• Efficiency


  Ratio of the amount of useful energy that's given out to the total amount of energy that was originally put in, calculated using the formula: Efficiency = Useful energy output / Total energy input
• Efficiency can be improved by reducing wasted energy transfers due to friction, air resistance, electrical resistance, and sound
• Types of energy resources


  • Non-renewable resources
  • Renewable resources
• Non-renewable resources


  Resources that we have a finite amount of, and will eventually run out of
• Renewable resources


  Resources that are replenishable and do not produce much energy compared to non-renewable resources
• Thermal energy is dissipated into the surroundings. If you can minimise these, you can improve the efficiency of a device.
• Types of energy resources


  • Non-renewable resources
  • Renewable resources
• Non-renewable resources


  Resources that we have a finite amount of, and will eventually run out of. They currently provide the majority of energy in the world. Their use usually results in environmental damage.
• Renewable resources


  Resources that are replenishable (will not run out). They do not produce much energy compared to non-renewable resources. They have minimal impact on the environment, however are generally less reliable than non-renewable resources.
• Non-renewable resources


  • Fossil fuels
  • Nuclear fuel
• Fossil fuels


  Energy sources formed from the ancient remains of living organisms. They include coal, oil, and natural gas. These fuels continue to be a major energy source worldwide due to their high energy content and ease of extraction.
• Nuclear power


  Uses energy from atoms, particularly uranium or plutonium, through a process called nuclear fission. This process releases a considerable amount of energy, and is then used to heat water, producing steam that drives turbines to generate electricity.
• Renewable resources


  • Wind power
  • Solar cells
  • Geothermal power
  • Hydro-electric power
  • Wave power
  • Tidal barrages
  • Bio-fuel
• Wind power


  Wind turbines use the kinetic energy from the wind to generate electricity. As the wind blows, it turns the blades of the turbine, which spins a generator inside the turbine's housing.
• Solar cells


  Solar cells, or photovoltaic cells in solar panels convert sunlight directly into electricity.
• Geothermal power


  Geothermal energy harnesses heat from the Earth's interior. Water or other fluids are pumped down to the hot regions, become heated, then return to the surface as steam or hot water. This steam rotates a turbine connected to a generator, producing electricity.
• Hydro-electric power


  Involves flooding a valley for the creation of large water reservoirs behind dams.
• Wave power


  Utilises small wave-powered turbines located around coasts.
• Tidal barrages


  The tides of the oceans go up and down due to the gravitational pull of the Moon and Sun. Tidal barrages are constructed across rivers, with turbines turning by using the energy from tidal movements.