P1 - Energy

• Internal energy

  The total kinetic and potential energy of all the particles that make up a system
• Doing work on a system

  Increases the energy stored in a system
• Heating a system


  Changes the energy stored in a system by increasing the energy of the particles within it
• As the energy increases


  Either the temperature increases or a change of state is produced
• Factors affecting temperature increase


  • Mass of the substance heated
  • What the substance is
  • Energy input
• Specific heat capacity


  The amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius
• Energy transfers

  Energy can be transferred usefully, stored or dissipated
• Energy cannot be created or destroyed
• In a closed system the total energy never changes, but it can be transferred from one store to another
• When an electric-powered lift raises the lift carriage

  1. Transfers electrical energy to gravitational potential energy

  2. Some energy is dissipated as heat and sound

  3. Wasted energy is no longer available for useful transfers
• Reducing wasted energy

  • Lubrication (reduces friction that produces heat)
  • Tightening loose parts (prevents unwanted vibration that wastes energy as sound)
  • Thermal insulation (reduces heat loss)
• A building loses heat to the surroundings


  The rate of cooling depends on the thickness and thermal conductivity of the walls
• Kinetic energy


  The energy of motion of an object, equal to the work it would do if brought to rest
• Gravitational potential energy


  The energy gained by raising an object above ground level (due to the force of gravity)
• Elastic energy


  The energy stored in a stretched / compressed elastic object, like a spring
• Internal energy

  The sum of the energy of all the particles that make up a system, i.e. the total kinetic and potential energy of all the particles added together
• Reproducible

  Results are reproducible if the investigation/experiment can be repeated by another person, or by using different equipment/techniques, and the same results are obtained, demonstrating that the results are reliable
• Renewable energy resources

  • Biofuel
  • Wind
  • Water (hydro)
  • Geothermal
  • Tidal
  • Solar
• Biofuel


  • Large areas of land needed for growing fuel crops, can be at expense of food crops in poorer countries
  • Does not provide a constant source of energy
• Wind

  • Turbines can be noisy / dangerous to birds
  • Some people think they ruin the countryside
• Water (hydro)


  • Requires large areas of land to be flooded, altering ecosystems and displacing residents
• Geothermal


  • Only available in a limited number of places where hot rocks are close to the surface
• Tidal


  • Variations in tides affect output
  • Have a high set-up cost
  • May affect habitats/shipping
• Solar


  • Depends on light intensity, so no power produced at night
  • High cost in relation to power output
• Non-renewable energy resources


  • Nuclear fuel
  • Coal
  • Oil
  • Gas
• Nuclear fuel

  • Produces radioactive waste but no other emissions
  • Costly to build and decommission
  • Reliable output
• Coal


  • Contributes to acid rain (SO)
  • Reliable output
• Oil


  • Burning produces greenhouse gases (CO₂) and contributes to acid rain (SO₂)
  • Reliable output
  • Provides a compact source of energy for transport
  • Serious environmental damage if spilt
• Gas


  • Reliable output
  • Burning produces CO, but not SO₂
• Transferred


  Refers to how energy is changed, e.g. chemical energy can be transferred to electric energy
• Dissipated


  Wasted, scattered or spread out (to the surroundings)
• Conductivity


  A measure of the ability of a substance to conduct electricity
• Renewable


  Can be replaced
• Specific Heat Capacity Required Practical:

  1. Set up an insulated beaker half full of liquid, with a heating coil inside that is connected to a voltmeter, an ammeter, and a power pack
  2. Measure start temp, then switch on the apparatus for 5 mins, then measure the end temp
  3. Measure the volume and current to find the power
  4. Repeat for different liquids and calculate the specific heat capacity

  
• Specific Heat Capacity Required Practical:

  • Independent Variable - type of liquid

  • Dependent Variable - temperature

  • Control Variables - volume of liquid, amount of energy provided
• Energy stores:

  • Gravitational potential

  • Nuclear

  • Elastic

  • Magnetic

  • Thermal

  • Electrostatic

  • Chemical

  • Kinetic
• Energy transfers:

  • Mechanical

  • Electrical

  • Heating • Radiation
• Power (w) = Work done (J) / Time (s)
• GPE = mass × gravitational field srength × height
• Kinetic energy = 1/2 × mass × velocity²