physics

• Energy

  The ability to do work, that is: make something move or change shape or speed or direction
• Work


  The application of force over a distance
• Calculating Work


  Work = Force (N) x Distance (m)
• Joule (J)


  A measurement of energy, equal to the work done when a force of 1 Newton acts to move an object a distance of 1 metre
• Name the missing Types of Energy

  • Thermal
  • Kinetic
  • Gravitational potential
  • Elastic potential
  • Chemical
  • Nuclear
  • Magnetic potential
  • Electrostatic potential
• Charged particles


  • Protons
  • Electrons
• Energy Transfer


  Energy can be transferred between objects. This means that one object loses energy, and another gains energy. Energy is transferred from one object to another in the form of mechanical work, electrical work, heat and radiation.
• Mechanical work


  Mechanical work is done on an object when a force is applied over a distance.
• Electrical work


  Electrical work is done when charges move through a circuit.
• Heat


  The transfer of energy from a hotter object to a cooler object.

  
• Radiation


  This includes energy transferred by light (or any electromagnetic wave) and sound.
• Car engine piston


  1. Fuel and air put into the engine

  2. The piston pushes up to compress fuel and air

  3. A spark plug ignites the fuel and air causing combustion

  4. The piston is pushed down causing the engine to turn
• Wind Turbine


  1. Wind (moving air) causes the turbine blades to rotate

  2. The wind turbine blades make an electrical generator rotate

  3. The electrical generator produces electricity
• The Law of Conservation of Energy states that energy cannot be created or destroyed, instead all energy is transferred to other objects or types of energy.
• Useful energy


  The work we wanted
• Waste energy


  The work we did not want
• Efficient device


  A device which transfers most of its input energy into useful work
• Inefficient device


  A device which transfers a small amount of input energy into useful work
• Energy efficiency


  The percentage of total input energy that is transferred into useful energy
• Calculating efficiency


  1. State equation

  2. Substitute values into equation

  3. Calculate answer
• Energy resources


  • Renewable
  • Non-renewable
• Non-renewable resource


  A resource which cannot be replaced within one lifetime once it has been used
• Non-renewable resources


  • Fossil fuels (oil, coal and gas)
  • Nuclear power
• Fossil fuels


  • They take so long to form, if we take too much out of the Earth, they will eventually run out
  • When you burn a fossil fuel, you release carbon dioxide which causes global warming
• Uses of fossil fuels

  • Power plants
  • Transport
  • Heating
• Electricity generation from non-renewable resources

  • They produce a reliable output
  • Burning fossil fuels increases the amount of carbon dioxide
• Renewable resources


  • Wind
  • Hydroelectric
  • Solar
• Wind


  • No carbon dioxide emissions, so they do not contribute to global warming
  • Once built, no fuel costs and so are cheap to run
  • It is not always windy, so the output is unreliable
  • Noisy & spoils the view
• Hydroelectric


  • Requires the flooding of a valley with a dam, which causes a loss of habitat
• Solar


  • Only work in direct sunlight, so do not generate electricity at night
• Heat


  The process of thermal energy being transferred from something hot to something cold

  
• Temperature


  A measure of the amount of thermal energy something has
• Thermal energy and the particle model

  1. Adding thermal energy causes particles to move faster

  2. Eventually particles have enough energy to change from solid to liquid to gas
• Conduction


  A type of heat that works by the collision of particles. Objects and particles must be touching for thermal energy to transfer by conduction.

  
• Thermal conductors


  Materials which are good at transferring thermal energy by conduction

  
• Thermal insulators


  Materials which are poor at transferring thermal energy by conduction
• Thermal radiation


  A type of heat that transfers thermal energy through infra-red radiation (a form of light that we can't see with our eyes)
• Absorbing and reflecting radiation

  • Dark coloured objects quickly absorb thermal radiation, while light coloured and reflective objects reflect thermal radiation
• Convection


  A type of heat that occurs in liquids and gases, and works by hot particles rising and cool particles falling
• How particles in liquids and gases move

  1. Particles gain thermal energy and rise up

  2. Particles lose thermal energy and fall lower