energy

• equation for kinetic energy:

  e = 1/2 x m x v*2
• equation for gravitational:

  e = m g h
• equation for elastic:

  e = 1/2 k x e*2
• energy stores

  • kinetic
  • thermal
  • gravitational potential
  • elastic potential
  • chemical
  • electrostatic
  • magnetic
  • nuclear
• energy transfers:

  • by heating
  • doing work
  • falling
• what is the conservation of energy?

  energy cannot be created or destroyed , only transferred , stored or dissipated
• what is specific heat capacity?

  energy required to increase the temperature of 1kg of a substance by 1*c
• equation for specific heat capacity:

  e = m c 0
• conduction:

  • occurs in solids
  • where vibrating particles transfer energy to eachother
• convection:

  • occurs in liquids and gases
  • where energetic particles move away from hotter to cooler regions
• how to reduce unwanted energy transfer:

  • cavity wall insulation
  • loft insulation
  • draught excluders
  • double glazed windows
• equation for efficiency:

  efficiency = useful output / total input x 100
• national grid:

  • use transformers to reduce unwanted energy transfers when transporting electricity
• step up transformers:

  increase the voltage and decrease the current

  • to reduce heat loss when travelling in cables
• step down transformers:

  decrease the voltage to 230v and increase the current

  • at safe values for safe home use
• renewable energy:

  • solar
  • wind
  • hydro-electric
  • biofuel
  • tides
• non-renewable energy:

  • coal
  • oil
  • natural gas
  • nuclear