work power and efficiency

• What are the different energy stores mentioned?

  Kinetic, gravitational, elastic, magnetic, electrostatic, chemical, nuclear, thermal
• What type of energy do moving objects have?

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

  When they are lifted through a gravitational field
• What happens to objects in their elastic potential store?

  They are stretched, squashed, or bent
• What type of energy do magnetic materials have?

  Energy in their magnetic store
• What is stored in the electrostatic energy store?

  Energy from charged objects interacting
• 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 in atomic nuclei
• What does the thermal store of an object depend on?

  The object's temperature
• What are the energy transfer pathways?

  Mechanical, electrical, heating, radiation
• What is mechanical working?

  When a force acts on an object
• How is electrical working defined?

  A charge moving through a potential difference
• How does energy transfer by heating occur?

  From a hotter object to a colder one
• What is energy transferred by radiation?

  Energy transferred by electromagnetic waves
• How can energy stores and transfers be represented visually?

  • Energy flow diagrams
  • Sankey diagrams
• What do Sankey diagrams represent?

  Energy transfers with proportions shown
• What does the left-hand side of a Sankey diagram represent?

  Energy transferred into the system
• What does the straight arrow in a Sankey diagram indicate?

  Useful energy output
• What do the bending arrows in a Sankey diagram represent?

  Wasted energy
• What does the conservation of energy state?

  Energy cannot be created or destroyed
• What is a closed system?

  Exchanges energy but not matter
• What is an isolated system?

  Does not allow energy or matter transfer
• What is wasted energy?

  Energy that is not useful
• What happens to energy when a bat hits a ball?

  Some energy transfers to the ball's kinetic store
• How does energy transfer occur when boiling water in a kettle?

  Energy is transferred electrically to the thermal store
• What happens to energy when a pan is heated on a hob?

  Energy is transferred from the hob to the pan
• How is work done calculated?

  Work done = force × distance
• What is work done in physics?

  When a force moves an object over a distance
• If a car applies brakes with a force of 500 N over 23 m, what is the work done?

  $11500 \text{ J}$
• What happens when a ball is lifted to a height?

  Energy is transferred to its gravitational potential store
• What is gravitational potential energy defined as?

  Energy due to height in a gravitational field
• How is the change in gravitational potential energy calculated?

  ΔGPE = m × g × Δh
• What does the symbol Δ represent in physics?

  Change in a quantity
• How does gravitational potential energy change with height?

  It increases as height increases
• What is transferred to the gravitational potential store when an object is lifted?

  Energy
• What happens to energy when an object falls?

  It is transferred away from gravitational potential store
• What does ΔGPE stand for?

  Change in gravitational potential energy
• How can the change in gravitational potential energy be calculated?

  Using the equation ΔGPE = m × g × Δh
• What does the symbol Δ represent in physics?

  Change in
• What is the relationship between GPE and height?

  • GPE increases with height
  • GPE decreases when falling
  • Linear relationship shown in graphs