Energy

• Unit of energy


  Joules (J)
• Stores of energy

  • Kinetic energy store
  • Gravitational potential energy store
  • Elastic potential energy store
  • Thermal energy store
  • Chemical store
• Ways energy can be carried when transferred between stores

  • Electrically by circuits
  • By heating
  • Mechanically / by a force
  • By radiation (including light)
• System


  A group of one or more objects
• The total amount of energy in a system is always conserved (stays the same), it is never created or destroyed
• Efficiency


  Useful energy / Total energy input
• Efficiency as a percentage


  Useful energy / Total energy input x 100
• Diagram used to show wasted energy and useful energy


  Sankey diagram
• Temperature


  How hot or cold something is
• Thermal energy


  The amount of energy stored in an object because of the movement of its particles
• Unit of thermal energy


  Joules (J)
• Food labels tell us how much energy is in the food we are eating
• Particles in a solid when heated

  • They vibrate more
• Particles in a liquid when heated

  • They move faster
• Particles in a gas when heated

  • They move faster
• Conductor


  A material that carries heat quickly
• Insulator


  A material which does not carry heat quickly, they stop heat from flowing
• Metals tend to be good conductors
• Non-metals tend to be good insulators