physics - energy resources

• What is the model for describing energy transfers in a system?

  Energy stores and transfer pathways
• How is a system defined in physics?


  As an object or group of objects
• Why is defining a system important in physics?

  It narrows parameters to focus on relevance
• What happens when a system is in equilibrium?

  Nothing changes, and nothing happens
• What occurs when there is a change to a system?

  Energy is transferred
• What happens to an apple when a table is removed?

  The apple falls due to gravity

  
• What is stored in different energy stores?

  Energy in various forms
• What are the different types of energy stores?

  • Kinetic
  • Gravitational
  • Elastic
  • Magnetic
  • Electrostatic
  • Chemical
  • Nuclear
  • Thermal
• What type of energy do moving objects have?

  Kinetic energy
• When do objects gain energy in their gravitational potential store?

  When lifted through a gravitational field
• What happens to energy in the elastic potential store?

  It is stored when objects are stretched or bent
• What is the electrostatic energy store associated with?

  Charged objects interacting with each other
• What type of energy do magnetic materials have?

  Energy in their magnetic store
• How is energy transferred in chemical reactions?

  Into or away from a substance's chemical store
• What releases energy from the nuclear store?

  Nuclear reactions
• How does temperature relate to thermal energy?

  The hotter the object, the more energy it has
• What are the energy transfer pathways?

  • Mechanical
  • Electrical
  • Heating
  • Radiation
• What is mechanical working in energy transfer?

  When a force acts on an object
• What does electrical working involve?

  A charge moving through a potential difference
• How is energy transferred by heating?

  From a hotter object to a colder one
• What is radiation in energy transfer?

  Energy transferred by electromagnetic waves
• How does a cup of hot coffee heat cold hands?

  By transferring energy through heating

  
• What are the steps to describe energy transfers in scenarios?

  1. Determine the energy store transferred from
  2. Determine the energy store transferred to
  3. Determine the transfer pathway
• In a battery powering a torch, where does energy transfer from?

  From the chemical store of the battery
• Where does energy transfer to in a battery powering a torch?

  To the thermal store of the bulb
• What is the transfer pathway in a battery powering a torch?

  Electrical transfer pathway
• What energy store does a falling object begin with?

  Gravitational potential store
• What energy store does a falling object transfer to?

  Kinetic energy store
• What is the transfer pathway for a falling object?

  Mechanical transfer pathway
• What remains constant in a closed system according to conservation of energy?

  The total amount of energy
• What does the principle of conservation of energy state?

  Energy cannot be created or destroyed
• What does dissipated energy refer to?

  Energy spread out to surroundings
• What is an example of wasted energy in a bat hitting a ball?

  Energy transferred to the thermal store

  
• How is energy transferred when boiling water in a kettle?

  From the mains supply to the thermal store

  
• What happens to energy in a kettle when it boils water?

  Some energy is wasted to surroundings
• What happens to energy when a person jumps on a trampoline?

  Most energy transfers to elastic potential store

  
• What is the useful energy transfer sequence on a trampoline?

  Elastic potential energy ➝ kinetic energy ➝ gravitational potential energy

  
• What does efficiency measure in an energy transfer?

  The amount of wasted energy
• How is efficiency defined?

  Ratio of useful energy output to total output
• What is the equation for efficiency?

  $\text{efficiency} =$$\frac{\text{useful energy output}}{\text{total energy output}} \times 100\%$