topic 9

• what is gpe (gravitional potential energy)

  • the energy stored in an object due to it's gravitional field
  • this means if an object is lifted up,it gains energy as it's transferred to her store and if it falls down it loses energy as it's transferred away
• what is the equation for gravitional potential energy

  gpe = mass x gravitional field strength x change in vertical height

  mass = kg, gravitional field strength n/kg x vertical height = meters
• what is the expected gravitional force for gravity

  • 10n/kg
• what is Ke (kinetic energy)

  the amount of energy an object has due to it's mass and speed

  any object in motion has kinetic energy
• what is equation for kinetic energy

  KE = 1/2 mass x velocity squared

  mass = kg

  velocity = m/s
• Describe energy transfers in a ball being thrown upwards

  • upwards ke is converted to gpe
  • maximum height maximum gpe and minimum ke
  • downwards gpe is converted back to kinetic energy
• describe energy transfers in a kettle being heated

  • energy is converted from electrical energy to the mains power supply to the thermal store heating element of the kettle
  • as it gets hotter heating element is converted to thermal store of the water
• describe energy transfers in a filament lamop

  • eletrical energy is converted to heat energy
  • electrical energy is useful and heat isnt
• describe the energy stores for the gpe for a bunjee jumper

  • gpe converted into kinetic energy
  • as cord tightens ke is converted to elastic potential energy
  • minimum point epe = initial kinetic energy
  • bunjee jumper slows down as ke is converted to epe
• what is power


  the rate at which energy is transferred or the rate at which work is done
• What are the two equations for power

  p = e /t (joules / time)

  p = work done / time (joules)
• what is the units for power

  watt
• what is work

  the force required to cause on object to move a certain distance
• equation for work done

  force x distance