Energy

• Types of energy stores


  • Gravitational potential
  • Electrical
  • Electrostatic
  • Kinetic
  • Sound
  • Light
  • Nuclear
  • Chemical
  • Thermal
  • Elastic potential
  • Magnetic
  • Internal energy (kinetic + potential that make up a system)
• System


  An object or group of objects. When a system changes, there are changes in the way energy is stored.
• Doing work on a system


  Increases the energy stored
• Heating a system


  Changes the amount of energy stored
• Increased energy


  Means an increase in temperature or change of state
• Increase in temperature


  Depends on mass, type of substance, energy input
• The Law of Conservation of Energy - Energy can't be created or destroyed only transferred to another type of energy
• Specific heat capacity


  The amount of energy required to raise the temperature of 1kg of the substance by 1°C
• Ways energy can be transferred


  • Mechanically (a force doing work)
  • Electrically (work done by moving charges)
  • By heating
  • By radiation (light or sound)
• Light bulb


  • Electrical energy is input, most of that is transferred to light energy (useful) & the rest heat & sound (wasted)
• To reduce unwanted energy transfers


  1. Lubricate moving parts

  2. Tighten loose parts

  3. Use thermal insulation
• Rate of cooling


  Depends on the thickness & thermal conductivity of the walls
• Thermal insulation methods in houses


  • Double(/triple) glazing
  • Cavity wall insulation
  • Draught excluder
  • Curtains
  • Carpet
  • Loft insulation
  • Jacket around hot water tank
• Efficiency


  Useful energy out/total energy in or Useful power out/total power in (% or decimal)
• Renewable energy resources


  • Biofuel
  • Wind
  • Hydro-electric
  • Geothermal
  • Tidal
  • Solar
  • Water waves
• Renewable energy resources


  • Won't run out, replenish as we use them
• Non-renewable energy resources


  • Nuclear
  • Coal
  • Oil
  • Natural gas
• Non-renewable energy resources


  • Finite, will run out