energy

• a system is an object or group of objects, when a system has a change the way energy is stored also changes
• specific heat capacity= the energy required to raise 1kg of a substance by 1C or 1K
• power= the rate at which energy is transferred or the rate work is done
• energy cannot be created or destroyed
• ways to reduce energy waste:

  • lubrication - reduces friction so less energy lost as heat
  • thermal insulation - double glazing so less useful thermal energy lost
• the higher the thermal conductivity of a material, heat can travel through the material more easily so the rate of energy transfer by conduction is higher.
• ways to increase efficiency of a system:

  • reducing waste output (lubrication, thermal insulation)
  • recycling waste output (absorbing thermal waste and recycling as input energy)
• non renewable energy sources:

  • nucleur
  • fossil fuels (finite resource)
• renewable energy sources:

  • biofuel
  • wind
  • hydro-electricity
  • geothermal
  • tidal
  • solar
• main energy uses:

  • transport
  • electricity generartion
  • heating