Energy

• Energy is the ability to do work - make things move or heat up
• Energy cannot be created or destroyed - only transferred
• if you turn on a lightbulb, energy is transferred from the chemical store of the battery to the thermal store of the bulb and then the room
• Ways to reduce energy transfers in the home-

  • loft insulation
  • cavity wall insulation
  • double glazing
  • foil behind radiators
• loft insulation reduces rate of energy transfer
• cavity wall insulation reduces energy transfer through outer wall
• double glazing traps air between glass
• foil behind radiators reflects heat from radiator
• specific heat capacity if the amount of energy needed to raise the temperature of a 1kg of a substance by 1°c
• useful energy is energy transferred in the way we want it to where we want it
• Types of energy -

  • Kinetic
  • Gravitational potential
  • Thermal
  • Elastic potential
  • Chemical
  • Nuclear
  • Electrostatic
  • Magnetic
• Types of energy transfers -

  • Mechanical
  • Electrical
  • Heating
  • Radiation
• work done is when a force causes movement, energy is needed and then transferred to the object
• power is a measure of how quickly energy is transferred
• the law of conservation of energy means that as an object falls the gravitational potential energy it loses must transfer to a different energy store
• elastic means the object returns to its original shape after being deformed by a force
• inelastic means an object that remains permanently deformed
• the spring constant tells us how stiff a spring is
• a system is an object or a group of objects
• a closed system is where no energy can be transferred to the surroundings
• thermal insulators have low conductivity
• lubrication reduces frictional forces, a moving object normally has at least one frictional force acting against it which causes energy to be dissipated