7.1 - Conservation of Energy

• Which two of the following are false?

  Energy can be created

  Energy can be destroyed 

  Energy can be transferred

  Energy can be stored

  Energy can be dissipated

  • Energy can be created
  • Energy can be destroyed 
• What happens to 'dissipated' energy?

  It is lost to the surroundings
• Open vs closed systems

  An open system can exchange energy and matter with its surroundings. A closed system cannot exchange energy or matter with the surroundings.
• As a bowl of hot porridge cools down, what happens to the energy in its thermal energy store? 

  It is transferred to the surroundings
• What is the main energy transfer of a marathon runner?

  Chemical energy ➔ kinetic energy
• Not all of the chemical energy from the runner's cells would be converted to kinetic energy, which other form is it most likely to be converted to?

  Thermal energy 
• What is the conservation of energy principle?

  Energy can be transferred, stored, or dissipated
• What does the conservation of energy principle imply about energy?

  Energy cannot be created or destroyed
• How does energy transfer occur when charging a phone?

  Electrical energy transfers to chemical energy
• What happens to chemical energy when using a phone?

  It converts back to electrical energy
• What type of energy conversion occurs in a phone's screen?

  Electrical energy to light energy
• What type of energy conversion occurs in a phone's speaker?

  Electrical energy to sound energy
• What is wasted energy typically in the context of a phone?

  Energy dissipated as heat
• Why might a phone warm up during use?

  Due to energy dissipated as heat
• What is a system in physics?

  A portion of the physical universe analyzed
• What is the environment in relation to a system?

  Everything outside the chosen system
• Why is a phone considered an open system?

  Energy and matter can move freely
• What happens when a phone gets hot in an open system?

  It gives out heat energy to surroundings
• What defines a closed system in physics?

  Energy and matter cannot enter or escape
• What happens to heat energy in a closed system with a phone?

  Heat energy dissipates to the air inside
• What does it mean for the overall energy of a closed system?

  It doesn't ever change
• What are the key concepts of the conservation of energy principle?

  • Energy can be transferred, stored, or dissipated
  • Energy cannot be created or destroyed
  • Energy moves between different objects and forms
• What are the energy transformations when charging and using a phone?

  1. Charging: Electrical energy → Chemical energy
  2. Using: Chemical energy → Electrical energy
  3. Screen: Electrical energy → Light energy
  4. Speaker: Electrical energy → Sound energy
• What distinguishes open systems from closed systems?

  • Open System: Energy and matter can move freely
  • Closed System: Energy and matter cannot enter or escape
• What are the implications of energy dissipation in systems?

  • Wasted energy typically appears as heat
  • Overall energy in a closed system remains constant