physics paper 1

• In a closed system, no energy is lost to the surroundings
• If there is less energy at the end of a reaction, it must have been lost to the surroundings by friction or air resistance
• Specific Heat Capacity Practical

  1. Measure mass of metal and water in beaker using top pan balance

  2. Place electrical heater in the metal block/water

  3. Measure initial temperature using thermometer

  4. Turn heater on, start timer and measure power supplied using voltmeter and ammeter

  5. After 60s, measure final temperature and calculate change in temperature

  6. Calculate power supplied to the block using P=VI

  7. Calculate energy supplied to the block using E=Pt

  8. Calculate specific heat capacity by rearranging SHC equation
• Energy cannot be created or destroyed
• Energy stores


  • Kinetic energy
  • Gravitational potential energy
  • Elastic potential energy
  • Thermal energy (specific heat capacity)
  • Sound/vibrational energy
  • Chemical energy (fuels, food, batteries)
• Kinetic energy


  E = 1/2 mv^2
• Gravitational potential energy


  E = mgh
• Thermal energy (specific heat capacity)

  E = mcΔT
• Dissipated energy


  Energy that is being stored in a way that is unuseful (usually energy has been transferred into thermal energy stores)
• In a closed system, energy transfers occur but the net change in energy is zero.
• What is power?

  The rate of energy transfer, or the rate of doing work
• What is power measured in?

  • Measured in watts, one watt = 1 joule of energy transferred per second
• Calculating power


  Power (W) = Energy transferred (J) / Time (s)

  Power (W) = Work done (J) / Time (s)
• A powerful machine is one which transfers a lot of energy in a short space of time, not necessarily one which can exert a strong force.
• In conduction, energy transferred to an object by heating is transferred to the thermal stores of the object and shared across the kinetic energy stores of the particles.
• Thermal conductivity is a measure of how quickly energy is transferred through a material by conduction.
• Convection is where energetic particles move away from hotter to cooler regions.
• In convection, the warmer and less dense region will rise above denser, cooler regions, creating a convection current.
• How do radiators create convection currents? Radiators create convection currents in a room by heating the nearby air particles, causing the warm air to rise and be replaced by cooler air.
• Lubricants


  • Can reduce frictional forces between objects, reducing energy dissipation
• Insulation


  • Can reduce the rate of energy transfer by heating
• Investigating the effectiveness of thermal insulation


  Pour water into a sealed container and measure initial temperature

  2. Leave for 5 minutes and measure final temperature

  3. Repeat with different insulating materials and compare temperature changes
• The thicker the insulating layer, the smaller the temperature change and the less energy is transferred.
• Efficiency


  Useful output energy transfer / Total input energy transfer
• Useful output energy is usually not equal to total input energy due to energy dissipation.
• Electric heaters are 100% efficient as all the energy in the electrostatic energy store is transferred to useful thermal energy stores.
• All energy eventually ends up transferred to thermal energy stores.
• Non-renewable energy resources


  • Coal
  • Oil
  • Natural gas
• Renewable energy resources


  • The Sun
  • Wind
  • Water
  • Hydroelectricity
  • Biofuels
  • Geothermal
• Non-renewable energy resources will run out one day and do damage to the environment.
• Renewable energy resources will never run out but most still do some damage to the environment, just in less nasty ways than non-renewables.
• Uses of energy resources


  • Electricity generation
  • Transport
  • Heating
• Main fossil fuels


  • Coal
  • Oil
  • Natural gas
• Fossil fuels will run out one day
• Fossil fuels do damage to the environment
• Renewable energy resources will never run out
• Renewable energy resources don't provide as much energy as non-renewables
• Renewable energy resources depend on natural phenomena like weather and cannot be increased to meet extra demand
• Transportation methods using renewable or recyclable energy resources


  • Vehicles running on bio-fuels or a mix of bio-fuel and petrol/diesel
• Transportation methods using non-renewable energy resources


  • Petrol and diesel powered vehicles
  • Steam trains using coal