energy (p1)

• Energy stores

  Thermal, kinetic, GPE, elastic, magnetic, chemical, nuclear, electrostatic
• Energy is never created or destroyed
• System

  An object or group of objects
• Closed system


  • No energy can leave
• Open system

  • Can lose or gain energy
• Energy transfer

  1. Mechanically

  2. Heating

  3. Electrically

  4. Infrared radiation

  5. Light

  6. Sound waves
• Work done


  When a force causes an object to move
• Electrical work


  When current flows against resistance
• Kinetic energy


  Energy an object has due to motion
• Elastic potential energy


  Energy stored in a stretched spring
• Gravitational potential energy


  Energy due to an object's position in a gravitational field
• Internal energy

  The total energy stored by the particles in a substance or system
• Specific heat capacity

  The amount of energy needed to raise 1kg of a substance by 1°C
• Measuring specific heat capacity- required practical

  1. place substance you are measuring the specific heat capacity off into a beaker and measure mass

  2. place immersion heater and thermometer into the oil

  3. record the starting temperature

  4. wrap beaker in insulating foam

  5. connect a joulemeter and power pack to the emersion heater

  6. leave for 30 mins

  7. read the number of joules of energy that passed into the immersion heater

  8. read the final temp of the oil
• Power


  The rate at which energy is transferred or work is done
• Energy can be transferred usefully, stored or dissipated but never created or destroyed
• Closed system


  • Energy and matter cannot enter or escape, overall energy does not change
• Conduction

  • Energy transferred by vibrating particles
  • transfer energy to neighbouring particles
• Convection

  • Energy transferred by movement of particles
  • transport their heat from hotter to cooler areas
• Radiation

  • Energy transferred by infrared waves
• Reducing unwanted energy loss

  1. Sealed closed to reduce convection

  2. Thick walls/cavity walls to reduce conduction

  3. Double glazing to reduce conduction

  4. Lubrication to reduce friction
• Measuring thermal insulation

  1. Wrap beakers in different insulating materials

  2. Fill with warm water

  3. Record initial and periodic temperatures

  4. Calculate temperature change
• Measuring effect of insulation thickness

  1. Wrap beakers in different thicknesses of insulating material use beaker with no insulation as a control

  add cardboards lids to all

  2. Fill with hot water

  3. Record initial and periodic temperatures

  4. Calculate temperature change
• Efficiency

  Useful energy output / Total energy input
• Energy resources

  • Renewable - biofuel, hydroelectric, geothermal, solar, wind
  • Non-renewable - fossil fuels, nuclear
• Hydroelectric power

  • Dams trap water, difference in water level generates electricity from GPE and kinetic energy
  • No pollution, reliable, immediate response to increased demand
  • Expensive initial setup, environmental impact
• Biofuels

  • Fuels made from recently living organisms like plants or algae
  • Carbon neutral, renewable, cheap, easy to transport
  • Need land to grow plants, processing requires energy
• Geothermal energy

  • Thermal energy generated and stored in the Earth's crust
  • Can be used directly for heat or to generate electricity
  • Renewable, stable, low environmental impact
  • Only available in certain areas, expensive to install
• Wind and solar energy

  • Wind turbines convert wind energy into electricity, solar panels convert sunlight into electricity
  • Low running costs, don't damage environment
  • High upfront cost, weather dependent, can't increase supply easily
• Nuclear energy

  • Energy obtained from nuclear reactions (fission)
  • Doesn't produce pollutants, can be used in any conditions, uranium unlikely to run out
  • Produces radioactive waste, expensive, risk of meltdown
• Fossil fuels

  • Hydrocarbons made from remains of dead organisms
  • Cheap, can be used in any conditions, current infrastructure designed for them
  • Limited resource, produce CO2 and other toxic gases when burned
• Wave power

  • Uses kinetic energy in waves to generate electricity
  • Renewable, no fuel costs, no pollutants
  • Difficult to scale up to produce large amounts of electricity, can damage wildlife