Physics P1 - P1

• A system as an object or group of objects.
• The specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
• Energy can be stored as:

  1. Kinetic energy (due to movement)

  2. Gravitational potential energy (due to distance above ground)

  3. Elastic potential energy (due to stretched or squashed objects)

  4. Thermal energy (due to temperature)

  5. Chemical energy (in food, fuels and batteries)
• Energy can be transferred from one store to another by: 1. Heating

  2. Waves

  3. Electric current

  4. When a force moves an object
• Power is defined as the rate at which energy is transferred or the rate at which work is done.
• An energy transfer of 1 joule per second is equal to a power of 1 watt.
• Energy cannot be created or destroyed but can be:

  • transferred usefully
  • stored
  • dissipated ('wasted' , stored in less useful ways)
• The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material. The best materials for thermal insulation have low thermal conductivity
• Ways to reduce unwanted energy transfer: - lubrication - thermal insulation
• The higher the thermal conductivity the higher the rate of energy transfer by conduction. This means that the best materials for thermal insulation have low thermal conductivity e.g. foam.
• A building’s rate of cooling is affected by two factors:

  • Thickness of walls, floors and roof
  • Thermal conductivity of walls, floors and roof
• A renewable energy resource is one that is being or can be replenished as it is used.
• The uses of energy resources include: transport, electricity generation and heating.
• Renewable energy resources:

  1. Biofuel
  2. Geothermal
  3. Wind
  4. Hydroelectric
  5. Tidal
  6. Wave
  7. Solar
• Non renewable energy resources:

  1. Coal (fossil fuel)
  2. Crude oil (fossil fuel)
  3. Natural gas (fossil fuel)
  4. Nuclear