Energy

• What is the law of conservation of energy?

  It states that energy cannot be created or destroyed, only transferred or transformed.
• What are the 8 energy stores?

  Chemical, thermal, kinetic, gravitational potential, elastic potential, nuclear, electrostatic, magnetic.
• What is Magnetic Energy?


  The energy stored by two magnets attracting or repelling one another
• What is Thermal Energy?


  The energy that comes from the movement of particles within a substance.
• What is Chemical Energy?


  Energy stored in Chemical bonds
• What is Kinetic Energy?

  The Energy of a moving Object
• What is Electrostatic Energy?


  The energy stored when repelling charges have been moved closer together or when attracting charges have been pulled further apart.
• What is Elastic Potential Energy?

  Energy stored in an elastic object when it is stretched or compressed.
• What is Gravitational potential Energy?


  The energy of an object at height in a gravitational field
• What is Nuclear Energy?


  Energy Stored from the in the nucleus of an atom.
• Energy can be transferred from one store to another by Mechanical working, Electrical working, Radiation, and Heating
• Mechanical working


  When a force is applied to move an object through a distance
• Electrical working


  When charge flows (electric)
• Radiation

  When energy is transferred as a wave, for example as light or sound
• Heating


  When energy is transferred between hotter and colder regions
• There are energy transfers going on all the time whenever a system changes, there is a change in the way some or all of the energy is stored
• Energy can remain in the same store for millions of years or sometimes just for a fraction of a second
• Boat loses chemical energy


  As fuel is burned
• Boat gains kinetic energy


  As it gains speed
• Transfer diagrams

  • They show the energy stores and transfers in a situation
  • The boxes show the energy stores and the arrows show the energy transfers
• What is Energy Efficiency?

  Using less energy to provide the same service.
• What does Efficiency tell you?

  Tells you how much energy is converted into useful energy
• How do you calculate Energy Efficiency?

  Useful Energy divided by total energy supplied
• What is Conduction?

  The particles vibrate to transfer energy .Happens in Solids only. The energy is transferred from a hotter region to a cooler region.
• How is Conduction Prevented?


  Non-Metals like plastics and Fabrics
• What is Convection?


  Is a Heat Transfer where the particles move rise and fall in a convection current
• In what states of matter does Convection happen in?

  Happens in Liquid and Gases
• What prevents Convection?


  Removing air flow
• What happens to hot and cold liquids/gases in a Convection Current?

  Hot air/liquid rises then as the water cools it becomes more dense and falls
• What is Radiation?


  Radiation is the transfer of heat energy from a region of high temperature to a region of low temperature by infrared radiation.
• What does Radiation not need?


  Particles
• Does heat transfer from Hot to cold or cold to hot?

  heat flows from the warmer body to the cooler body until they reach the same temperature
• What Prevents Radiation?


  Shiny/White Surfaces reflect Radiation
• How/Why is air a good insulator?


  They are poor conductors of heat because they have less contact, due to further spacing, between molecules. Heat transfer requires contact between molecules and thus gases are generally good insulators.
• Improving efficiency of systems designed to transfer thermal energy


  1. Reducing the wasteful dissipation of thermal energy to the surroundings

  2. Using insulation
• Efficient heating of buildings is important in reducing the amount of energy used
• Thermal energy will transfer from inside warm buildings to the cooler surroundings outside


  Reducing this thermal energy transfer is important
• Materials that are poor conductors


  Brick, wood, plastic, glass
• A house built of conducting materials like copper would be very cold to live in, as energy would be able to leave the house easily
• How do you Calculate Kinetic Energy?


  1/2 x mass x Velocity^2