energy

• Energy stores -

  • a system is an object or group of objects
  • when a system changes the way energy is stored also changes
• gravitational potential energy - energy stored in an object due to its gravitational force
• GPE formula - $Ep =$$m g h$
• thermal energy - energy due to heat
• power - the rate of energy transfer
• specific heat capacity -the amount of energy required to raise 1kg of a substance by 1 degrees celcius
• elastic potential - energy stored in a stretched object
• kinetic energy - energy due to motion
• conservation of energy - energy cannot be created or destroyed only transferred
• wasted energy - energy that is transferred in a form that is not a desired outcome
• efficiency = useful energy out / total energy in
• units for specific heat capacity - joules / degrees / kg
• units for power = Watts
• non - renewable energy resources - gas, oil, coal, nuclear power
• Gas, oil, coal collectively known as fossil fuels : burning these results in the emission of green house gases which contribute to global warming
• nuclear power - power plants don't release CO2 but produce radioactive waste which must be contained
• renewable resources - Biofuel , wave power, hydro electricity , solar power, tidal power, wind energy , geothermal energy
• renewable energy resources never run out : tend to be less damaging to the environment
• energy can be transferred usefully, stored or dissipated but never created or destroyed
• reducing energy waste :

  lubrication

  - oil in a motor

  - reduces friction

  - so less energy is lost ( at heat) through friction

  
  

  thermal insulation :

  • double glazing
  • less thermal useful energy lost
• thermal conductivity - the higher the thermal conductivity of a material , heat is transferred easily. The higher rate of energy by conduction through the material
• Efficiency - the ratio of useful work done by a machine, engine, device etc, to the energy supplied to it often expressed as a percentage
• the efficiency of a system can be increased by :

  • reducing waste output
  • recycling waste output
• renewable energy is not always reliable -

  • solar doesn't work in bad weather or night
  • wind is intermittent
• main energy uses :

  • transport
  • electricity generating
  • heating
• extraction of energy :

  • fossil fuels involve destroying landscapes
  • wind turbine can be considered as an eyesore
• Use of energy sources

  • fossil fuels release harmful emissions
  • solar, wind directly create electricity with no emissions
• types of energy stores

  • chemical
  • thermal
  • magnetic
  • kinetic
  • electrostatic
  • elastic potential
  • gravitational potential
  • nuclear
• thermal energy - total kinetic and potential energy of the particles in an object, in most cases this is vibrations, also known as the kinetic energy of particles . In hotter objects they have more internal energy and vibrate faster
• chemical - the energy stored in chemical bonds, such as those between molecules
• kinetic - the energy of a moving object
• electrostatic - the energy stored when repelling charges have been moved closer together or when attracting charges are pulled further apart
• elastic potential - the energy stored when an object is stretched or squashed
• gravitational potential - the energy of an object at height
• nuclear - the energy stored in the nucleus of an atom
• energy can be transferred

  • mechanically
  • electrically
  • infrared radiation
  • light or sound waves
  • through heating
• an open system - gain or lose energy to outside world
• What is the main focus of the video discussed in the study material?

  To explore how to reduce unwanted energy transfers using thermal insulation and lubrication
• What is one common desire people have for their homes during cold weather?


  To keep their home nice and warm
• Why is it important to reduce heat energy loss in a house?


  To maintain a warm environment inside despite cold weather outside