Physics - Energy Resources and Energy Transfer

• Energy stores

  • Kinetic
  • Thermal
  • Chemical
  • Gravitational potential
  • Elastic potential
  • Electrostatic
  • Magnetic
  • Nuclear
• Kinetic energy store


  • Anything moving
• Thermal energy store


  • Any object - the hotter it is, the more energy it has in this store
• Chemical energy store

  • Anything that can release energy by a chemical reaction, e.g. food, fuels
• Gravitational potential energy store

  • Anything in a gravitational field (i.e. anything which can fall)
• Elastic potential energy store

  • Anything stretched, like springs and rubber bands
• Electrostatic energy store

  • e.g. two charges that attract or repel each other
• Magnetic energy store

  • e.g. two magnets that attract or repel each other
• Nuclear energy store

  • Atomic nuclei release energy from this store in nuclear reactions
• Energy transfer


  1. Mechanically - an object moving due to a force acting on it, e.g. pushing, pulling, stretching or squashing

  2. Electrically - a charge moving through a potential difference, e.g. charges moving round a circuit

  3. By heating - energy transferred from a hotter object to a colder object, e.g. heating a pan of water on a hob

  4. By radiation - energy transferred e.g. by light/sound waves, e.g. energy from the Sun reaching Earth as light
• Energy can be stored, transferred between stores, and dissipated - but it can never be created or destroyed.
• Energy is only useful when it is transferred from one store to a useful store.
• Efficiency Formula


  efficiency = useful energy output/total energy output X 100
• Energy can be transferred in 3 ways :

  • Radiation
  • Conduction
  • Convection
• What is Thermal Radiation?

  Thermal Radiation is the transfer of energy by heating by infrared electromagnetic waves
• Conduction and Convection are energy transfers that involve the transfer of energy by particles
• Conduction is the main form of energy transfer by heating in solids
• Convection is the main form of energy transfer by heating in liquids and gases
• Thermal Radiation occurs in solids, liquids, gases. It can occur on any object, whether or not conduction or convection are also taking place.
• The bigger the temperature difference, the faster the energy is transferred between the thermal energy stores and its surroundings.
• An object that's hotter than its surroundings emits more radiation than it absorbs.
• An object that's colder than its surroundings absorbs more radiation that it emits.
• Thermal conduction is the process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy stores of neighboring particles.
• Thermal Convection occurs when the more energetic particles move from the hotter region to the cooler region - and transfer energy as they do.
• Convection can't happen in solids because the particles can't move.
• To stop convection, you need to stop the fluid moving and prevent convection currents from forming.
• Vacuums/Pockets of air in a hydroflask is a method of insulation as the air is trapped. So the air can't move, so the energy has to conduct very slowly through the pockets of air.
• Black Colour - Good at absorbing and emitting radiation compared to a white.

  Matt Surface - Better at absorbing and emitting radiation compared to a shiny one.
• When a force moves an object through a distance. Work is done on the object and energy is transferred.
• Work Done = Force X Distance Moved
• What is power?


  Power is the rate in which energy is being transferred
• Work Done = Energy Transferred
• 700W means it can transfer 700J of energy in a second
• Kinetic Energy Formula


  KE = 1/2 x mass x speed²
• Gravitational Potential Energy Formula


  GPE = Mass x Gravitational Field Strength x Height
• Non-Renewable Energy Generators :

  • Coal
  • Oil
  • Natural Gas
  • Nuclear Fuels
• How steam is used to drive turbines :

  • Fossil Fuels burn which heat up water.
  • This water boils to become steam which then turns the turbine.
  • This turbine generates electricity from the generator.
• Fossil Fuels :

  +

  • Releases a lot of energy, and is relatively cheap.
  • Doesn't rely on weather like most renewable energy does.
  • Don't need to spend more on new technology as we already have alot.

  -

  • releases C02 which contribute to global warming and climate change.
  • releases sulfur dioxide/acid rain which harms trees, soils and wildlife.
  • eventually going to run out.
• Power Stations - uses steam

  Chemical - Thermal - Kinetic - Kinetic - transferred electrically

  
  

  Nuclear Reactors - uses heat

  Nuclear - thermal - transferred mechanically to kinetic - transferred electrically to national grid.

  
  

  Wind Farms - uses wind

  Kinetic Energy - transferred electrically

  
  

  Geothermal Power - uses heat from underground

  Thermal - kinetic
• Convection is the transfer of energy in liquids and gases by when the more energetic particles move from the hotter region to the cooler region - where they transfer energy as they do so