Conservation of energy

• What is the conservation of energy principle?

  • Energy can be transferred
  • Energy can be stored
  • Energy can be dissipated
  • Energy cannot be created or destroyed
• Can energy be created or destroyed according to the conservation of energy principle?

  No, energy cannot be created or destroyed; it can only be transferred or converted between different forms.
• When you plug your phone into the wall to charge it, what type of energy is initially transferred from the main supply?

  Electrical energy
• What type of energy is stored in your phone's battery after it's charged?

  Chemical energy
• How does chemical energy in the battery power your phone?

  1. Chemical energy is converted to electrical energy
  2. Electrical energy flows around the circuit
  3. Powers different parts of the phone (screen, speaker)
• What type of energy is converted to light energy on your phone's screen?

  Electrical energy
• What type of energy is converted to sound energy by your phone's speaker?

  Electrical energy
• What is the ideal outcome of energy transfer in your phone?

  Every time energy is transferred, it is transferred usefully into the desired store without dissipation.
• What is meant by 'dissipated energy' in the conservation of energy principle?

  • Energy lost to forms other than the intended form
  • Generally in the form of heat
• Besides heat, in what other form can energy be dissipated from your phone?

  Sound energy
• Why might your phone warm up while charging?

  Because electrical energy is dissipated as heat during charging.
• What is a system in physics?

  • A portion of the physical universe chosen for analysis
  • Everything outside the system is the environment
• What term describes a system where energy and matter can freely move between the system and the environment?

  Open system
• What term describes a system where energy and matter cannot enter or escape?

  Closed system
• How does heat energy behave in a closed system?

  Heat energy is dissipated to the air inside the jar, remaining within the system.
• What is true about the overall energy of a closed system?

  The overall energy of a closed system does not ever change.