energy

• Reducing energy waste


  • Lubrication
  • Thermal insulation
• Thermal conductivity


  The higher the thermal conductivity of a material, heat is allowed to travel through the material more easily, so the higher the rate of energy transfer by conduction across the material
• Main Energy Sources


  • Non-renewable: Fossil Fuels, Nuclear Fuel
  • Renewable: Biofuel, Wind, Hydro-electricity, Geothermal, Tidal, Solar, Water waves
• Renewable energy


  Energy which can be replenished as it is used
• Non-renewable energy


  Used more for large-scale energy supplies due to the large energy output per kilogram of fuel
• Main Energy Uses


  • Transport
  • Electricity generation
  • Heating
• Environmental Impact


  • Extraction of Energy: Fossil fuels destroy landscapes, Wind turbines can be considered an eyesore
  • Use of Energy Sources: Fossil fuels release harmful emissions, Solar and wind create electricity with no emissions
• Only recently has renewable energy become more suitable - technology has had to develop a lot since industrial revolution to be able to harness such energy sources efficiently
• A system


  An object or a group of objects
• Kinetic energy

  What is the energy associated with movement?
• Elastic potential energy


  What type of energy is stored in stretched objects
• Nuclear energy

  What type of energy is found in the nuclei of atoms?
• Gravitational Potential Energy


  What type of energy is found in objects raised off the ground?
• Thermal energy


  What type of energy is stored as heat?
• Chemical energy


  What type of energy is found in bonds between substances?
• Kinetic energy = 0.5 x mass x speed^2


  What is the equation to work out the kinetic energy of a moving object?
• Elastic potential energy = 0.5 x spring constant x extension^2


  What is the equation to work out the elastic potential stored in a spring?
• Joules (J)


  What is the unit for energy?
• G.P.E = mass x gravitational field strength x height


  What is the equation to work out gravitational potential energy of an object raised off the ground?
• kg


  What is mass measured in?
• m/s


  What is speed measured in?
• N/m

  What is spring constant (Ek) measured in?
• m

  What is extension measured in?
• 0.2m

  If an object started at 5cm long and stretched to 25cm then what would be the value for extension?
• N/kg


  What is gravitational field strength measured in?
• Change in thermal energy = mass x specific heat capacity x temperature change


  How can you calculate the change in thermal energy?
• The amount of energy required to increase the temperature of 1kg of a substance by 1 degree celsius


  What is specific heat capacity?
• Power

  The rate at which energy is transferred or the rate at which work is done
• Power = Energy transferred / time

  How do you calculate power using energy transferred?
• Power = work done / time


  How do you calculate power using work done?
• Watts (W)


  What is power measured in?
• 1J


  How much energy is transferred each second if the power is 1W?
• The higher the power, the faster the object would be lifted.

  If you have two motors lifting a weight to the same height but one has more power, then what will be the difference between the rate at which they are lifted?
• Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed

  What is the law of the conservation of energy?
• Wasted energy

  What do we call energy that is dissipated?
• There will be no net change in the total energy

  In a closed system what will happen to the total energy?
• Use lubricants or insulation to reduce energy being wasted as heat

  How can we reduce the amount of waste energy in a system?
• The higher the conductivity, the faster the rate of conduction

  How does thermal conductivity of a material affect the rate of conduction across the material?
• The thicker the wall, and the lower its conductivity, the slower it will lose heat.


  How does the thickness of a wall affect the rate of cooling of a building?
• Efficiency = Useful output energy transfer/total input energy transfer


  How do you calculate efficiency using energy output?