Physics

• What are the different types of energy stores?

  Elastic potential, gravitational potential, thermal, electrostatic, nuclear, chemical, kinetic, magnetic, light, and sound
• How is energy transferred mechanically?

  By a force doing work
• What is the formula for kinetic energy?

  $E =$$\frac{1}{2}mv^2$
• What does gravitational potential energy depend on?

  Mass, gravitational field strength, and height
• What happens to energy when an object falls without air resistance?

  Energy lost from the gravitational potential energy store equals energy gained in the kinetic energy store
• What effect does air resistance have on falling objects?

  It transfers some energy to other energy stores, such as thermal energy stores
• What is the formula for elastic potential energy?

  $E =$$\frac{1}{2}ke^2$
• What does SHC stand for?

  Specific Heat Capacity
• What is the conservation of energy principle?

  Energy can be transferred, stored, or dissipated, but never created or destroyed
• What is power defined as?

  The rate of energy transfer or the rate of doing work
• What is 1 Watt equal to?

  1 Joule of energy transferred per second
• What is the formula for energy transferred in terms of power?

  $E =$$Pt$
• What is conduction?

  The process where vibrating particles transfer energy to neighboring particles
• What is thermal conductivity?

  A measure of how quickly energy is transferred through a material via conduction
• What is convection?

  Where energetic particles move from hotter to cooler regions
• What is the process of convection currents created by radiators?

  1. Energy is transferred from the radiator to nearby air particles by conduction.
  2. The air becomes warmer and less dense, rising and displacing cooler air.
  3. The previously heated air transfers energy to the surroundings, cools, becomes denser, and sinks.
• What does lubrication do?

  Reduces frictional forces
• What does insulation do?

  Reduces the rate of energy transfer by heating
• What are some thermal insulation techniques?

  • Cavity walls with an air gap
  • Cavity wall insulators filled with foam
  • Loft insulation to reduce convection currents
  • Double-glazed windows with an air gap
  • Draught excluders to reduce convection
• How can efficiency be improved?

  By lubrication, insulation, and making objects more streamlined
• What is the efficiency equation?

  Efficiency = useful output energy transfer / total input energy transfer
• Is any device 100% efficient?

  No
• Where is wasted energy usually transferred?

  To thermal energy stores
• How do thick walls prevent energy losses through heating?

  They are made from materials with low thermal conductivity
• What objects are usually 100% efficient?

  Electric heaters
• What are the advantages and disadvantages of fossil fuels?

  Advantages:

  • Reliable
  • High energy content

  
  

  Disadvantages:

  • Non-renewable
  • Cause acid rain and global warming
  • Environmental damage from extraction
• What are the energy resources used for transport?

  • Petrol and diesel (non-renewable)
  • Coal (steam trains, non-renewable)
  • Bio-fuels (renewable)
• What are the energy resources used for heating?

  • Natural gas (non-renewable)
  • Coal (non-renewable)
  • Electric heaters (non-renewable)
  • Geothermal (renewable)
  • Solar water heaters (renewable)
  • Bio-fuels (renewable)
• What are the advantages and disadvantages of wind power?

  Advantages:

  • Renewable
  • No pollution
  • Doesn't cause global warming

  
  

  Disadvantages:

  • Noisy
  • Spoils the view
  • Not always reliable
• What are the advantages and disadvantages of solar power?

  Advantages:

  • Renewable
  • No pollution
  • Doesn't cause global warming

  
  

  Disadvantages:

  • Solar panels are expensive
  • Not always reliable
• What are the advantages and disadvantages of geothermal power?

  Advantages:

  • Renewable
  • No pollution
  • Very little environmental damage

  
  

  Disadvantages:

  • Not very reliable
  • Limited to certain locations
• What are the advantages and disadvantages of hydroelectric power?

  Advantages:

  • Renewable
  • Reliable
  • No pollution

  
  

  Disadvantages:

  • High initial costs
  • Environmental impact
• What are the advantages and disadvantages of wave power?

  Advantages:

  • Renewable
  • No pollution

  
  

  Disadvantages:

  • High initial costs
  • Disturbs marine habitats
• What are the advantages and disadvantages of tidal power?

  Advantages:

  • Renewable
  • Reliable
  • No pollution

  
  

  Disadvantages:

  • High initial costs
  • Alters wildlife habitats
• What are the advantages and disadvantages of bio-fuels?

  Advantages:

  • Renewable
  • Carbon neutral
  • Reliable

  
  

  Disadvantages:

  • Can cause global warming
  • Loss of natural habitat
• What are the advantages and disadvantages of nuclear power?

  Advantages:

  • Reliable
  • No pollution

  
  

  Disadvantages:

  • High decommissioning costs
  • Produces radioactive waste
• What is the method for investigating specific heat capacities?

  1. Measure mass of a block and wrap it in insulation.
  2. Measure initial temperature and set power supply to 10V.
  3. Turn on power and record temperature and current every minute.
  4. Calculate power supplied and plot energy transferred against temperature.
• What is the method for investigating the effectiveness of materials as thermal insulators?

  1. Boil water and pour into a sealable container.
  2. Measure initial temperature and seal for 5 minutes.
  3. Measure final temperature and repeat with different materials.
• What is a closed system?

  A system where neither matter nor energy can enter or leave
• Why did electricity use increase in the 20th century?

  Due to population growth and increased use of electricity