Physics paper 1 AQA combined

• Systematic error


  Caused by poor equipment
• Scale


  Always reads to 0.5kg lighter
• Solution


  Add 0.5kg to every mass
• Random error


  Caused by lack of precision of equipment
• Random error


  • I do the same experiment 3 times and get 11g, 10g and 12g
• Solution


  Repeat more and calculate a mean
• System


  An object or group of objects
• System


  • Can store energy (the ability to work)
• Types of energy


  • Magnetic
  • Kinetic
  • Thermal
  • Gravitational potential
  • Chemical
  • Elastic potential
  • Electrostatic (positive and negative attractions)
  • Nuclear
• Energy transfer


  Energy is moved between stores
• Ways energy is transferred

  • Heating (because temperature difference)
  • Mechanically (when a force moves through a distance)
  • Electrically (when a current flows)
  • By radiation (light, microwaves, sound)
• Conservation of energy


  • In a closed system, the energy cannot be created or destroyed, only transferred
  • The amount of energy always stays the same
  • Energy is only transferred between stores
  • Energy is transferred through energy pathways
• Gravitational potential energy


  Energy gained by raising an object against the action of a gravitational field
• Kinetic energy


  Energy stored by a moving object
• Elastic potential energy


  Energy stored in a stretched spring or elastic band
• Specific heat capacity


  The energy that a substance absorbs to cause it to change temperature by 1 degree
• Power


  The rate at which energy is transferred
• Efficiency


  The proportion of energy which is usefully transferred
• Efficiency is decreased by more wasted energy
• There is almost always some energy that ends up as a thermal store in the surroundings and dissipates into the surroundings as internal energy
• Ways to reduce wasted energy

  • Reducing heat lost (insulation, thermal conductivity of materials)
  • Reducing drag (streamlining)
  • Reducing friction (using wheels, lubrication)
• Renewable electricity


  A resource that is being generated faster than it is being used
• Renewable electricity sources


  • Biofuel
  • Tidal
  • Hydroelectric
  • Wave
  • Wind
  • Solar
  • Geothermal
• Non-renewable electricity


  A resource that is being used faster than it is being generated
• Non-renewable electricity sources


  • Coal
  • Oil
  • Gas
  • Nuclear
• Advantages of renewable electricity

  • Cheap (coal, oil, gas, biofuel, geothermal)
  • No CO2 emissions (nuclear, tidal, wave, hydroelectric, wind, solar, geothermal)
  • Reliable (coal, oil, gas, nuclear, biofuel, tidal, geothermal)
  • Can be used anywhere in the country (coal, oil, gas, nuclear, biofuel, solar)
• Disadvantages of renewable electricity

  • CO2 emissions from burning fossil fuels
  • Non-renewable
  • Unreliable
• Cell


  Chemical energy store
• Battery


  Two or more cells in series
• Switch


  Breaks circuit, stops current
• Lamp


  Emits light when current flows
• Ammeter


  Measures current
• Voltmeter


  Measures potential difference
• Diode


  Current flows one way
• LED


  Emits light when current flows
• Resistor


  Affects the size of current flowing
• LDR


  Resistance low in bright light
• Variable resistor


  Allows current to be varied
• Thermistor


  Resistance low at high temperature
• Fuse


  Melts when current is too high