energy stores and transfers

• Gravitational potential energy store


  Stored in lifted masses, or water behind a dam

  
• Kinetic energy store


  Energy stored in a moving object

  
• thermal energy store


  the energy a substance has because of its temperature

  
• Elastic potential energy store


  Also known as strain energy, stored when objects change shape (stretch or squash)

  
• Nuclear energy store


  Also known as atomic energy

  energy stored in atoms and released by nuclear reactions

  
• Chemical energy store


  Energy stored in food, fuels and in batteries

  
• By heating


  energy transferred from a hotter object to a colder object

  
• By forces or mechanically

  Energy transfer eg by friction

  
• By light (or other radiation)


  Energy transferred from very hot objects

  
• By sound


  Energy transfer by noises eg music, speech

  
• By electricity


  How energy is transferred from a battery or generator to where it is required

  
• Law of conservation of energy


  states that energy cannot be created or destroyed, it can only be transferred from one store to another
• Joule


  unit of energy or work
• Energy efficiency


  useful energy / total energy
• Decimal or percentage


  Efficiency is measured in
• Dissipated


  Energy that has become spread out or 'wasted' by heating the environment.
• Most common waste energy

  By heating the surroundings
• 1 kJ kilojoule


  1000 J
• 1 MJ mega joule

  1,000,000 J
• 1 GJ giga joule

  1,000,000,000 J
• work


  another term for energy
• 1mJ millijoule


  0.001J
• Lifted masses


  An example of gravitational potential energy; when the mass is dropped, the potential energy is converted into other forms of energy
• Gravitational potential energy


  The energy a body has due to its position in a gravitational field, dependent on the mass of the object and its height above the ground
• Water behind a dam

  Another example of gravitational potential energy; when the water is released, the potential energy is converted into other forms of energy
• Mass


  The amount of matter in an object; the greater the mass, the greater the gravitational potential energy
• Height above the ground

  The vertical distance of an object from the ground; the higher the object, the greater the gravitational potential energy
• Generator


  A machine that converts kinetic energy into electrical energy by using the motion of a coil of wire within a magnetic field to create an electrical current
• Kinetic energy


  The energy of motion; the energy an object has due to its motion or movement
• Turbine


  A device that converts the kinetic energy of a fluid (such as water or air) into mechanical energy, often used to generate electricity
• Electrical current


  The flow of electric charge; the rate at which electric charge flows through a conductor
• Magnetic field


  A region around a magnet or electric current where the force of magnetism acts on other magnetic materials or moving charges
• A system in physics is defined as an object or group of objects
• When a system is in equilibrium, nothing changes, and so nothing happens
• When there is a change to a system, energy is transferred
• If an apple sits on a table, and that table is suddenly removed, the apple will fall
• As the apple falls, energy is transferred
• Energy Stores


  • Kinetic
  • Gravitational
  • Elastic
  • Magnetic
  • Electrostatic
  • Chemical
  • Nuclear
• Kinetic energy store


  Moving objects have energy in their kinetic store
• Gravitational potential energy store


  Objects gain energy in their gravitational potential store when they are lifted through a gravitational field