Energy

• Gravitational potential


  9.8 N/Kg
• Food, fuels, and battery


  Have chemical energy
• System


  An object (particle) or a group of them
• Specific heat capacity


  The minimum energy required to raise 1kg of an object by 1°c
• Rollercoaster example


  1. Higher it is, more gravitational potential energy

  2. As it rolls down, gravitational potential energy transfers into kinetic energy

  3. Gravitational potential energy lost = kinetic energy gained

  4. If less kinetic energy at bottom then gravitational at top, energy has been lost to the surroundings by friction/air resistance (open system)
• Power


  Measure of energy transfer, joules per second
• Efficiency


  How much of energy transfer is actually useful output energy
• Thermal conductivity


  How fast heat travels through stuff
• Lubricants (liquids)


  Reduce frictional forces
• Thermal insulation strategies


  • Loft insulation
  • Double glazing
  • Cavity wall insulation
• Fossil fuels


  • Coal
  • Oil
  • Natural gas
• Fossil fuels


  • Burnt to produce heat and steam for driving turbines and generators
  • Produces greenhouse gases which contributes to global warming
• Nuclear fuel (uranium)


  • Setting up power, carrying out nuclear fission to produce energy
  • Produces more energy than renewable but more dangerous so more disasters occurring
• Wind turbines


  • Wind has kinetic energy, used to spin turbines
  • No release of greenhouse gases
  • Rely on wind in area so inefficient
• Solar panels


  • Uses light from sun for electricity
  • Expensive and relies on sun being out
• Ways energy can be transferred

  • Mechanical work
  • Electrical work
  • Heating
• Mechanical work


  Energy transferred from one object to another via a force
• Electrical work


  An electrical current transfers energy from one object to another
• Heating


  Heating an object transfers energy to its internal store
• Vehicle slowing down


  1. Vehicle's energy is in the kinetic store

  2. Brakes do work slowing the car down

  3. Energy is dissipated (lost) through heat and sound
• Boiling water in an electric kettle

  Energy transfers from the electrical store of the mains power supply to the thermal store of the water