Energy

• what are the 8 energy stores?

  Chemical, Thermal, Nuclear, Gravitational, Elastic, Electrostatic, Magnetic and Kinetic
• how can energy be transferred?

  radiation - sun light

  electrically - by moving charges

  mechanically - force doing work
• what is a system?

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

  The law of conservation states that energy cannot be created or destroyed, only transferred or transformed.
• what is an equation that links kinetic energy, mass and speed?


  Ek = 1/2 x m x v2
• what is an equation that links mass, gravitational field strength and height?


  Ep = m x g x h
• what is an equation that links elastic potential energy, spring constant and extension


  Ee = 1/2 x k x e2
• what is the work done equation?

  W = F x S
• what is a closed system?

  where energy cannot be gained or lost to the outside world
• conduction


  vibrating particles transfer energy to neighbouring particles
• convection

  • particles gain thermal energy
  • thermal energy is transferred into kinetic energy
  • vibrate and move so bonds break and particles begin to move apart
  • the substance becomes less dense and begins to rise
• why are metals good conductors?

  • metals have alot of free electrons
  • the electrons are free to move around and vibrate
  • heat energy is passed on to neighbouring particles
• perfect black body radiation


  an object that absorbs all of the radiation incident on it
• does a black body reflect or tansmit any radiation?


  no
• if an object is cooler than its surroundings 


  it absorbs IR radiation at a higher rate than it emits IR radiation
• what can be concluded about how the distribution pf the intensity of radiation from an object changes as the temperature of the object increases?

  • the intensity of every wavelength increases
  • the shorter the wavelength the more rapid the increase in intensity
  • the peak intensity occurs at shorter wavelength
• w=


  w= m x g
• if the resultant force is 0


  the object will remain stationary
• F=


  F=k x E
• P= 


  P= m x v
• thinking distance


  the distance travelled while the brain processes the need to stop
• breaking distance


  the distance travelled when breaks are applied
• stopping distance


  thinking plus breaking distance
• reaction time


  the length of time taken for a person to respond to a given stimulus or event
• what effects thinking distance?

  • alcohol
  • age
  • eyesight
  • tiredness
  • distractions
• what effects braking distance?

  • tyre condition
  • road
  • brake
  • mass of car
• what effects both thinking and braking distance?

  speed
• moment


  turning effect of a force
• centre of mass


  the point at which an objects mass can be thought of as being concentrated
• m=


  m= f x d
• series circuit


  current stays the same but voltage is shared between components
• parallel circuit


  current is shared between branches but voltage stays the same