energy

• energy cant be created or destroyed, only transfered from one store to another
• energy stores (ck get men)

  • chemical
  • kinetic
  • gravitational
  • elasticity
  • thermal
  • magnetic
  • electrostatic
  • nuclear
• energy transfers

  • sound
  • electricity
  • by heat
  • by radiation
• a sankey diagram summarise all the energy transfers taking place in a process

  
• efficiency

  a measure of how good a device is at changing input energy into useful energy
• efficiency = useful energy out / total energy in x 100
• wasted energy = friction between moving components means the thermal store of the surroundings and the object is filled
• use oil to reduce friction meaning a reduce in heat loss
• kenetic energy(J) = 1/2 x mass(kg) x velocity^2 (m/s)
• gravitational energy(J) = mass(kg) x gravitational field strength(N/kg) x height (m)
• GE lost = KE gained
• thermal conductivity

  a measure of how good a material is at letting heat pass through it
• high thermal conductivity= conductor

  low thermal conductivity= insulator