Energy

• energy


  tells us if we are able to do something
• Many things have energy because of what they are doing or what they are. This is called 'stores'.
• 8 different energy stores:

  • chemical
  • nuclear
  • magnetic
  • electrostatic
  • thermal (heat)
  • kinetic (movement)
  • gravitational potential
• kinetic


  energy stored in a moving object
• gravitational potential


  energy stored in an object that is lifted above ground, in the gravitational field
• elastic


  energy when an object is stretched, squashed or twisted
• magnetic


  energy stored when repelling poles are pushed closer together or attracting poles are pulled further apart
• chemical


  energy stored in chemical bonds between atoms in fuels, food and batteries
• electrostatic


  energy stored when repelling charges are pushed closer together or attracting charges are pulled further apart
• thermal


  energy stored when an object is hot/warm
• nuclear


  energy stored in the nucleus of an atom
• law of conservation energy:

  • energy cannot be made/destroyed
  • energy can only be transferred between energy stores
• energy pathway:

  • mechanically by force (change in position)
  • electrically by electric current (electricity)
  • by heating (change in temperature)
  • radiation/waves (sound)
• efficiency


  how much energy is supplied to an object and is transferred in a useful way
• higher the useful energy output, the more efficient the device
• efficiency equation


  useful energy output/total energy input (x100%)
• 1kj = 1000j
• fuels


  substances with energy in its chemical store

  releases the stored energy as heat to the surrounding when it is burned
• How was coal made?

  1. Plant dies
  2. When the plant dies, it is buried in mud. It doesn't decompose as much due to the mud
  3. The layers of mud bury the plants along with the heat from the Earth which produces coal.
  4. Animals and plants die
  5. They settle on the seabed
  6. They become buried under layers of mud and sand. They were not able to decompose, forming crude oil and natural gas.
• How is electricity generated in a power station?

  1. Coal arrives by truck
  2. The fossil fuels is burned in the furnace
  3. Water in the boiler heats up and turns into steam
  4. Steam turns the turbine, which is attached to the generator
  5. The generator turns and creates an electric current
  6. Steam is cooled and turns back into the water
• Combustion

  A reaction when substances burn
• investigation


  energy transferred by fuels during combustion