energy

• Renewable energy resource


  An energy source which can be replenished as it is being used up
• Non-renewable energy resource


  Fossil fuels (for example coal, oil and gas)
• Advantages of generating power using gas rather than coal

  • Flexible Generation: Gas power stations have short start-up times so can be switched on/off more readily
  • Lower emissions of carbon dioxide
• Disadvantages of using renewable energy resources to generate power

  • Output often determined by external factors (like wind speed), so supply is uncertain
  • Generating power through other means is often more efficient and economically beneficial
• Burning fossil fuels


  • Carbon Dioxide contributes to the greenhouse effect, and causes global warming
  • Sulphur Dioxide leads to acid rain, which can damage buildings and crops
• Advantages of fossil fuels as an energy resource

  • Reliable: Not dependent on external factors so can generate power anytime
  • Can produce large amounts of energy for a given quantity
  • Still relatively abundant, so cost-effective
• Advantages of nuclear power

  • Very large amounts of energy for relatively small quantities of fuel
  • Doesn't release greenhouse gases and so doesn't contribute to climate change
  • Low fuel costs
• Disadvantages of nuclear power

  • Produces nuclear waste which is harmful to humans & must be safely stored for centuries
  • Non-Renewable energy source
  • Risk of nuclear accidents, which have fatal consequences on humans and the environment
• How hydroelectric power produces energy

  1. Rainwater collects behind a dam

  2. When this water is released, it is used to turn a turbine

  3. This turbine turns a generator which produces electricity
• Disadvantages of using biofuels

  • When plants are burned or decay they release CO2
  • In order to grow biofuels, you need to destroy land which leads to problems because: The land could have been natural habitats, Destroying land may involve burning plants growing on it, which would release CO2
  • Growing biofuels reduces the land available for growing food
• Advantages of tidal energy sources

  • They do not produce greenhouse gases
  • They are quite reliable, as tides happen twice a day
  • They are cheap to run as tides are natural, and so are free
• Disadvantages of hydroelectric power

  • The dam may cause flooding
  • It can cost a lot to install the required infrastructure
• Advantages of solar panels

  • They don't cause harm to the environment
  • They are a renewable resource
  • They can be used in remote areas where other types of energy are less accessible
• Social factors which may act as a deterrent for certain types of energy production


  • Visual Pollution
  • Sound Pollution
• Energy cannot be created or destroyed (it can only be transferred into different forms)
• Changes in the total energy of a ball that is kicked, assuming that no external forces act


  The total energy of the system remains constant due to the conservation of energy
• Waste energy


  The energy that is not used by the device for its desired purpose
• Energy changes that occur in a filament light-bulb


  1. Electrical energy is transferred into light and heat energy

  2. Light is a useful energy form, heat is waste energy
• Efficiency (equation 1)


  Useful Output Energy Transfer/Total Input Energy Transfer
• Efficiency (equation 2)


  Useful Power Output/Total Power Output
• How to increase the efficiency of a system

  1. Reducing waste output (by lubrication, thermal insulation etc.)

  2. Recycling waste output (eg. recycling thermal waste energy as input energy)
• Consequence of a material with high thermal conductivity


  The rate of energy transfer through the material is higher than for a material with a lower thermal conductivity
• Double-glazed windows have a lower thermal conductivity than single-glazed windows
• Factors affecting the rate of cooling of a building

  • The thickness of the walls
  • The thermal conductivity of the walls
• Methods of reducing heat loss in a building

  • Double glazing
  • Loft and wall insulation
  • Thicker walls
• How to improve the efficiency of a mechanical machine with moving parts (Higher)

  Lubricate any moving parts to reduce the friction and therefore energy loss due to heating
• How to improve the efficiency of a radiator (Higher)

  Installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls
• How to improve the efficiency of boiling water in a pan (Higher)

  By placing a lid on the pan to reduce the heat loss from the top
• Kinetic energy equation


  ½ m v2
• Kinetic energy equation


  • Energy (J), Mass(kg), Velocity(m/s)
• Elastic potential energy equation

  ½ k x2
• Elastic potential energy equation


  • Energy (J), Spring Constant (N/m), Extension(m)
• Gravity potential energy equation

  • Energy (J), Mass(kg), Gravitational Field Strength (N/kg), Height (m)
• Specific Heat Capacity


  The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius
• Specific Heat Capacity


  • J/°C/kg
• Power


  The rate at which energy is transferred (or rate at which work is done)
• Power equations


  • power = energy transferred/time
  • power = work done/time
• Power


  • Energy (J), Work Done (J), Time (s)
• Unit of power


  Watt (W)
• Two motors lift the same mass through the same height. Motor A does this in half the time of Motor B

  Motor A dissipates the most power