Topic 3 Conservation of Energy

• What is the formula for calculating the change in gravitational potential energy (GPE)?


  ∆GPE = mg∆h
• What does the equation ∆GPE = mg∆h represent?

  It calculates the change in gravitational potential energy as an object moves between heights.
• What units are used for mass, gravitational field strength, and change in vertical height in the GPE formula?

  Mass is in kilograms (kg), gravitational field strength in newtons per kilogram (N/kg), and height in metres (m).
• What do energy transfer diagrams illustrate?

  • Energy input and output
  • Forms of energy involved
  • Waste output energy
  • Energy wasted as heat in motors
• What happens to kinetic energy (KE) when an object is projected upwards?

  • KE is transferred to gravitational potential energy (GPE)
  • As the object falls back down, GPE is converted back to KE
• What occurs when an object is projected up a slope?

  • KE is transferred to GPE
  • Some energy may also be converted to heat due to friction
• What happens when a moving object hits an obstacle?

  • KE is transferred to sound energy
  • KE may also be transferred to the obstacle if it moves
• What occurs when an object is accelerated by a constant force?

  • Work is done on the object, increasing its KE
  • The energy supplying the force is transferred to KE
• What happens to kinetic energy (KE) when a vehicle slows down?

  • KE is transferred to heat through the brakes
• How is electrical energy transformed when boiling water in a kettle?

  • Electrical energy is converted to thermal energy
• What does the conservation of energy principle state?


  The total energy of an isolated system remains constant.
• What is a 'closed system' in physics?

  A closed system has no external forces acting on it.
• What happens to energy in a closed system?

  The total energy never changes, regardless of energy transfers.
• What occurs when a system becomes an open system?

  Energy can be transferred out of the system, changing the total energy.
• What is mechanical waste energy?

  • Energy transferred to an object can cause a rise in temperature
  • Energy is dissipated to surroundings, making the process wasteful
• What are common forms of waste energy?

  • Light
  • Sound
  • Heat (most common)
• How can waste energy be reduced?

  • Lubricate systems to reduce friction and heat
  • Use thermal insulation to minimize heat loss
• How do thicker walls in buildings affect thermal insulation?

  • Thicker walls provide greater thermal insulation, reducing heat loss
• What is the purpose of cavity wall insulation?

  • It fills air cavities between walls to prevent heat loss by convection
• How is efficiency defined in energy transfer?

  Efficiency is the ratio of useful output energy to total input energy.
• How can efficiency be increased?

  By reducing waste output and recycling waste energy as input.
• What are some sources of energy?

  • Fossil Fuels
  • Nuclear Fuel
  • Bio-Fuel
  • Wind
  • Hydro-electricity
  • Tidal
  • Solar
• Why are non-renewable energy sources used more for large-scale energy supplies?

  Because they provide a large energy output per kilogram of fuel.
• Why has renewable energy become more important recently?

  Due to the finite lifetime of fossil fuels and the need for sustainable energy sources.
• What trend occurred during the industrial revolution regarding energy sources?

  • Fossil fuels became an important energy source
  • They were easy to mine and provided a lot of energy
• What has changed regarding renewable energy since the industrial revolution?

  • Renewable energy has become more suitable
  • Technology has developed to harness these energy sources efficiently