energy stores

• energy is transferred between...

  stores
• energy store


  a means by which an object stores energy
• thermal energy store


  - filled when an object is heated up

  - emptied when an object is cooled down
• energy stores

  - thermal

  - kinetic

  - gravitational potential

  - elastic potential

  - chemical

  - magnetic

  - electrostatic

  - nuclear
• thermal energy store examples

  human bodies, hot coffees, stoves or hobs
• kinetic energy store


  - filled when an object speeds up

  - emptied when an object slows down
• kinetic energy store examples

  runners, buses, comets
• gravitational potential energy store

  - filled when an object is raised

  - emptied when an object is lowered
• gravitational potential energy store examples

  aeroplanes, kites, mugs on a table
• elastic potential energy store

  - filled when an object is stretched or squashed

  - emptied when an object returns back to its original state
• elastic potential energy store examples

  drawn catapults, compressed springs, inflated balloons
• chemical energy store


  - filled during endothermic reactions

  - emptied during exothermic reactions
• magnetic energy store


  - filled when repelling poles have been pushed closer together - emptied when attracting poles have been pulled further apart.
• magnetic energy store examples

  fridge magnets, compasses, maglev trains which use magnetic levitation
• electrostatic energy store


  - filled when repelling charges have been moved closer together - emptied when attracting charges have been pulled further apart.
• electrostatic energy store examples

  thunderclouds, Van De Graaff generators
• nuclear energy store


  - filled in the nucleus of an atom

  - emptied through radioactive decay, fission or fusion
• nuclear energy store examples

  uranium nuclear power, nuclear reactors
• energy is transferred...

  - mechanically

  - electrically

  - by heating

  - by radiation
• how is energy transferred mechanically?

  an object moving due to a force acting on it
• how is energy transferred electrically?

  a charge moving through a potential difference
• how is energy transferred by heating?

  from hotter objects to colder objects
• how is energy transferred by radiation?

  with electromagnetic waves
• system


  - a single object

  - a group of parts that work together as a whole
• when a system changes...

  energy is transferred
• energy can be transferred ... or ... from the system


  into, away
• closed systems


  systems where neither matter nor energy can enter or leave
• the net change in the total energy of a closed system is...


  always zero
• work done is another way of saying...

  energy transferred
• work done (J)=


  force (N) x displacement (m)
• work done formula


  W=Fs
• work done formula triangle

  
• kinetic energy (J)=


  1/2 x mass (kg) x velocity² (m/s)
• kinetic energy formula


  KE=1/2mv²
• gravitational potential energy (J)=

  mass (kg) x gravitational field strength (N/kg) x height (m)
• gravitational potential energy formula

  GPE=mgh
• elastic potential energy (J)=

  1/2 x spring constant (N/m) x extension (m)
• elastic potential energy formula


  EPE=1/2ke²
• change in thermal energy (J) =

  mass (kg) x specific heat capacity (J/kg°C) x temperature change (°C)
• change in thermal energy formula

  ΔE = mcΔθ