topic 1- energy

• What is a system in physics?

  An object or group of objects
• What happens to kinetic energy when a ball hits a wall?

  • Kinetic energy is transferred as sound
  • The system is the moving ball
• What occurs to a vehicle's kinetic energy when it slows down?

  • Kinetic energy transfers to thermal energy
  • This occurs due to friction between wheels and brakes
• What type of energy is stored in a stretched spring?

  Elastic potential energy
• What is specific heat capacity?

  Energy to raise 1kg by 1°C
• How is power defined in physics?

  Rate at which energy is transferred
• What is the relationship between joules and watts?

  1 joule per second equals 1 watt
• How can you determine which motor is more powerful?

  The one that does work faster
• What are the ways energy can be transferred?

  • Usefully
  • Stored
  • Dissipated
  • Cannot be created or destroyed
• What is energy dissipation in systems?

  • Energy is stored in less useful ways
  • Often described as 'wasted' energy
• How can lubrication reduce energy waste?

  • Reduces friction
  • Less energy lost as heat
• How does thermal insulation help in energy conservation?

  • Reduces thermal energy loss
  • Example: Double glazing
• What is thermal conductivity?

  Rate at which heat travels through a material
• How does wall thickness affect thermal conductivity?

  Thicker walls reduce cooling rate
• What is efficiency in a system?

  Ratio of useful work to energy supplied
• How can efficiency be increased?

  By reducing waste output and recycling
• What are the main non-renewable energy sources?

  • Fossil Fuels (coal, oil, gas)
  • Nuclear Fuel
• What are the main renewable energy sources?

  • Biofuel
  • Wind
  • Hydro-electricity
  • Geothermal
  • Tidal
  • Solar
  • Water waves
• What is the difference between renewable and non-renewable energy?

  Renewable can be replenished; non-renewable cannot
• Why is renewable energy becoming more important?

  Due to the finite lifetime of fossil fuels
• What are some reliability issues with renewable energy?

  Solar doesn't work at night; wind is intermittent
• What are the main uses of energy?

  • Transport
  • Electricity generation
  • Heating
• What are the environmental impacts of energy extraction and use?

  Extraction:

  • Destroys landscapes (fossil fuels)
  • Wind turbines can be eyesores

  Use:

  • Fossil fuels release harmful emissions
  • Solar and wind have no emissions
• How did the industrial revolution affect energy use?

  • Fossil fuels became important due to ease of mining
  • Renewable energy technology has developed since then
• What challenges exist in using energy resources today?

  • Increasing public power demands
  • Environmental issues are complex
  • Political, social, ethical, and economic considerations