energy

• what is a system?

  an object or a group of objects
• what is the principle of conservation of energy?

  energy can not be created / destroyed, only transferred from on store to another
• what are the different stores of energy?

  • chemical = fuels, food, batteries
  • kinetic = moving objects
  • gravitational potential = objects above the ground
  • elastic potential = objects that are stretched / squashed
  • thermal energy = due to temperature
  • magnetic = magnets
  • electrostatic = due to electric charges repelling / attracting
  • nuclear = when nuclei inside atoms join / separate
• what is the energy transferred to unwanted form of energy is what?

  wasted
• what is the unit of energy?

  joules
• what is efficiency?


  a measure of how good a device is at changing energy (or power) from one form to another
• what diagram shows useful and wasted energy?

  sankey
• what are the properties of a sankey diagram?

  • The thickness of the arrows shows how much energy is involved.
  • the width should be proportional to the amount of energy being transferred
  • Useful energy transfers are shown going left to right.
  • Wasteful energy transfers are shown going upwards or downwards.
• what is power?


  the rate at which energy is transferred.
• what is a kilowatt equivalent to?

  1000 watts
• what is work done?

  When an object is moved a distance by a force, work has been done on the object
• what does energy transferred equal?

  work done
• what is internal energy?

  It is the total kinetic energy and potential energy of all the atoms and molecules of the system
• what does heating do to particles?

  increases the energy which either increases the kinetic energy or changes the state
• what is specific heat capacity?

  the amount of energy needed to increase the temperature of 1kg of a substance by 1C
• would a material with a high heat capacity need more or less energy to heat up 1kg by 1C?

  more
• how can heat be transferred?


  1. conduction (mostly in solids)
  2. convection (in liquids and gases)
  3. radiation (a type of electromagnetic radiation that can travel through a vacuum)
• what does thermal conductivity tell us?

  how well a material conducts heat
• The higher the thermal conductivity of a material the higher the what?

  the rate of energy transfer by conduction across the material.
• the thicker the material, the lower the what?

  thermal conductivity
• how can we reduce heat loss from a house?

  • draught stoppers
  • loft insulation
  • double glazing
  • carpets
  • cavity wall insulation
• The rate of cooling of a building is affected by the what?

  the thickness and the thermal conductivity of its walls.
• what is kinetic energy?

  any object that is moving
• The greater the mass or velocity of the object, the greater or lesser the amount of kinetic energy?

  greater
• what is gravitational potential energy?

  the energy an object has due to being raised above the ground
• what is elastic potential energy?

  The energy stored in a spring when work is done in compressing or stretching
• what does the spring constant measure?

  how difficult it is to compress or stretch a spring e.g. The larger the spring constant the more difficult is to compress or stretch.
• how can we generate electricity?

  through renewable and non renewable resources
• what are the non renewable resources?

  coal, gas, oil, nuclear
• what are the uses of the non renewable energy sources?

  • coal = Electricity generation, heating, transport.
  • oil = heating, transport.
  • gas = Electricity generation, heating, transport.
  • nuclear = Electricity generation, military transport.
• what are the environmental impacts if non renewable sources?

  • coal = Burning produces greenhouse gases, contributes to acid rain, Reliable output
  • oil = Reliable output, Provides a compact source of energy for transport, Burning produces greenhouse gases, contributes to acid rain, Serious environmental damage is spilt.
  • gas = Reliable output, Burning produces greenhouse gases
  • nuclear = produces radioactive waste but no other emissions, Costly to build and decommission, Reliable output.
• what are the renewable resources?

  biofuel, wind, hydroelectric, geothermal, tidal
• what are the uses of the renewable resources?

  • biofuel = transport, electricity generation
  • wind = Electricity generation
  • hydroelectric = Electricity generation
  • geothermal = Electricity generation, heating
  • tidal = Electricity generation
  • solar = Electricity generation, heating.
• what are the environmental impacts of biofuel, wind, and solar?

  • biofuel = Large areas of land are needed for growing fuel crops. This can be at the expense of food crops in poorer nations.
  • wind = Unreliable as only provides energy while there is wind, Turbines can be noisy/dangerous to birds, Some people think they ruin the appearance of the countryside
  • solar = Depends on light intensity, so no power produced at night, High cost in relation to power output
• what are the environmental impacts of geothermal, tidal, and hydroelectric?

  • geothermal =Only available in a limited number of places where hot rocks can be found close to the surface (e.g. Iceland)
  • tidal = Variation in tides affect output. Have a high initial set-up cost, Can alter habitats/cause problems for shipping
  • hydroelectric = Requires large area of land to be flooded, altering ecosystems and displacing the people that live there.