Topic 3-Conservation of Energy

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

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

  Change in gravitational potential energy
• What units are used for mass in the GPE equation?

  Kilograms (kg)
• What does 'g' represent in the GPE equation?

  Gravitational field strength
• What is the equation for kinetic energy (KE)?

  KE = ½ mv²
• What does the equation KE = ½ mv² calculate?

  Kinetic energy of a moving object
• What units are used for kinetic energy?

  Joules (J)
• What do energy transfer diagrams show?

  Energy input, output, and forms
• What happens to KE when an object is projected upwards?

  KE is transferred to GPE
• What occurs when an object falls back down?

  GPE is converted back to KE
• What happens to KE when an object moves up a slope?

  KE is transferred to GPE and heat
• What occurs when a moving object hits an obstacle?

  KE is transferred to sound or obstacle
• What happens when an object is accelerated by a constant force?

  Work is done, gaining KE
• What happens to KE when a vehicle slows down?

  KE is transferred to heat through brakes
• What energy transformation occurs when boiling water in a kettle?

  Electrical energy to thermal energy
• What does conservation of energy mean in physics?

  Total energy remains constant in an isolated system
• What is a closed system?

  No external forces acting on it
• What happens to total energy in a closed system?

  Total energy never changes
• What occurs when a system becomes open?

  Energy can be transferred out
• What is mechanical waste energy?

  Energy causing a rise in temperature
• How is energy dissipated in mechanical processes?

  Heat is transferred to surroundings
• What are common forms of waste energy?

  Light, sound, and heat
• How can waste energy be reduced?

  Lubricate systems and thermal insulation
• What is the effect of thicker walls in buildings?

  Greater thermal insulation, less heat loss
• What is cavity wall insulation used for?

  Prevent air flow and heat loss
• How is efficiency defined?

  Useful output over total input of energy
• How can efficiency be increased?

  Reduce waste output and recycle waste
• What are some sources of energy?

  Fossil fuels, nuclear fuel, bio-fuel
• Why are non-renewable energy sources used more for large-scale supplies?

  Large energy output per kilogram of fuel
• Why has renewable energy become more important?

  Finite lifetime of fossil fuels
• What trend occurred during the industrial revolution regarding energy sources?

  Fossil fuels became an important energy source
• What has allowed renewable energy to become more suitable recently?

  Technological development since the industrial revolution
• What are the energy changes when an object is projected upwards?

  • KE transferred to GPE
  • GPE converted back to KE when falling
• What are the energy changes when an object moves up a slope?

  • KE transferred to GPE
  • KE transferred to heat if friction is present
• What are the energy changes when a moving object hits an obstacle?

  • KE transferred to sound
  • KE transferred to obstacle if it moves
• What are the methods to increase efficiency?

  • Reducing waste output
  • Recycling waste output
  • Suitable methods depend on the situation
• What are the patterns and trends in the use of energy resources?

  • Fossil fuels became important during the industrial revolution
  • Renewable energy has become more suitable recently due to technology