energy stores

• Energy


  Never created or destroyed, only transferred between different forms and objects
• Forms of energy


  • Thermal or internal energy
  • Kinetic energy
  • Gravitational potential energy
  • Elastic potential energy
  • Chemical energy
  • Magnetic energy
  • Electrostatic energy
  • Nuclear energy
• Energy transfer


  1. Mechanical

  2. Electrical

  3. Heating

  4. Radiation (light or sound waves)
• System


  Collection of matter
• Open system


  Can exchange energy with the outside world
• Closed system


  Separate from the outside world, no exchange of matter or energy
• Energy transfer example 1

  • Electrical energy from plug socket to kettle's heating element, then to water's thermal energy
• Work done


  Energy transferred
• Types of work done

  • Mechanical
  • Electrical
• Mechanical work done example

  • Kicking a ball, energy from leg's chemical energy to ball's kinetic energy
• Electrical work done example


  • Energy required to overcome resistance in wires of a circuit
• Friction slows down a train


  Causes energy transfer from wheel's kinetic energy to thermal energy of surroundings