topic p1- energy

• kettle heating: electrical

  • thermal
  • sound
• arm throwing ball up: chemical

  • kinetic
• energy stores

  • thermal
  • elastic potential
  • chemical
  • gravitational potential
  • nuclear
  • kinetic
  • magnetic
  • electrostatic
• work done

  is another way of saying energy transferred
• work can be done

  • when current flows or
  • by a force moving an object
• energy is transferred:

  • mechanically
  • electrically
  • by heating
  • by radiation
• movement means energy in an objects kinetic energy store

  the greater the mass the higher the kinetic energy
• raised objects store energy in gravitational potential energy stores

  • the higher the object is lifted, the more energy is transferred
  • the amount of energy depends on the mass, height and strength
• falling objects transfer energy

  • when something falls energy is transferred from gpe to kinetic energy
• stretching can transfer energy to elastic potential energy stores

  • stretching or squashing an object can transfer to its elastic potential energy store, so long as the limit of proportionality has not been exceeded
• specific heat capacity

  • is how hard it is to heat something up
  • different materials have different specific heat capacities
  • more energy needs to be transferred to the thermal energy store of some materials to increase their temperature than others
  • is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree celcius
• change in thermal energy=

  mass x specific heat capacity x temperature change
• energy can be transferred usefully, stores or dissipated, but can never be created or destroyed= conservation of energy
• power

  • is the rate of energy transfer, or the rate of doing work
  • is measured in watts
  • one watt= 1 joule of energy transferred per second
• power=

  energy transferred/ time (s)
• power=

  work done/ time (s)
• lubrication reduces frictional forces

  • lubricants can be used to reduce the friction between the objects surfaces when they move
  • they are usually liquids (oil) so they can flow easily between objects and coat them
• insulation reduces the rate of energy transfer by heating

  to prevent energy loss through heating:

  • have thick walls
  • loft insulation
  • thermal insulation
  • double-glazed windows
  • cavity wall insulation
  • draught excluders
• conduction

  • is the process where vibrating particles transfer energy to neighbouring particles
  • only happens in solids
• convection

  • is where energetic particles move away from hotter to cooler regions
  • only happens in liquids and gases
• power=

  current ^2 x resistance
• power=

  potential difference x current
• power=

  work done/ time
• resistance=

  potential difference/ current
• efficiency=

  useful output energy/ total input energy x 100
• kinetic energy=

  1/2 x mass x speed ^2
• non-renewable energy resources:

  • will all run out one day
  • cause damage to the environment
  • but they provide most of our energy
• non-renewable energy resources:

  • coal
  • oil
  • nuclear
  • natural gases
• renewable energy resources:

  • will never run out
  • most of them do damage to the environment; but it is not as bad as non-renewable
  • they don't provide as much energy
  • can be unreliable
• renewable energy resources:

  • the sun
  • wind
  • waves
  • hydroelectric
  • geothermal
  • tidal
  • biofuel
• renewable

  • wind
  • solar
  • geothermal
• wind power= lots of little wind turbines

  • places on moars or coasts
  • unreliable
  • cause no pollution
  • expensive
  • eyesaw/ noisy
  • no permanent damage to landscape
• solar power= expensive but no environmental damage

  • generate power from the sunlight
  • unreliable
  • used in remote places
  • expensive
  • cause no pollution
• geothermal power= energy is underground thermal energy stores

  • only can be used in certain places
  • reliable
  • free
  • little damage to the environment
• hydro-electric requires flooding of a valley via a dam
• tidal barrages are built across river estuaries to generate electricity
• renewable energy

  • hydro-electric
  • waves
  • tidal
• hydro-electric power uses falling water

  • no pollution
  • loss of habitat
  • reliable
  • large impact on environment (flooding)
  • expensive
• wave power- lots of little wave-powered turbines

  • located around the coast
  • unreliable
  • expensive
  • no pollution
  • destroying habitats
  • small amounts (energy)
• tidal power- uses sun/ moon's gravity

  • no pollution
  • spoiling the view
  • expensive
  • reliable
  • altering habitats
  • prevents access by boats