Energy

• What is the unit of energy?

  Joules
• What is the unit of power?

  Whatt
• How many joules are in a

  kilojoule?

  1000 J = 1 kJ
• How many watts are in a

  kilowatt?

  1000 W = 1 kW
• What is the equation used to work out kWh on an

  energy bill?

  kWh = power (kW) x time (hours)
• Power = energy transferred (J)
• What is the power of a:

  1. lightbulb that transfers 9000 J of energy in 90 s


  9000 / 90 = 100 W
• What is the power of b: a kettle that uses 20 kJ in 10 ss?

  20000 / 10 = 2000 W or 2 kW
• What is the equation used to work out kWh on an

  energy bill?

  kWh = power (kW) x time (hours)
• In science, what does work mean?

  transfer of energy
• What is the equation used to

  work out work done?

  work done (J) = force (N) x distance (m)
• If Mr Boorman pushes his golf trolley with a force of 30 N over a

  distance of 100 m, how much work was done?

  30 x 100 = 3000 J (or 3 kJ)
• scizzors are an example of what

  lever
• a rowing machine is an example of what

  pulley
• An energy company charges 34p per kilowatt hour

  (kWh). How much does is cost to run: A 1kW heater for 7 hours?

  1 x 7 x 34 = 238 p or £ 2.38
• 2). A 500W microwave in 30 minutes. 34p per kilo watt hour. calculate how much it costs to run.

  500 W = 0.5 kW 30 mins = 0.5 hours

  0.5. x 0.5 x. 34 = 8.5 p
• In what direction does thermal energy flow

  hot to cold
• Why would an ice cube melt quicker in a beaker of hot

  water compared to a beaker of room temperature

  water?

  There is a greater difference in temperature
• How is temperature different to thermal energy?

  • Temperature is a measure of how hot a substance is, - Thermal energy is the total energy stored in all the

  particles in a substance
• what is conduction 


   The transfer of energy, such as heat or an electric charge, through a substance.
• what is convection 


   the process of transferring heat through air or liquid currents.
• What is radiation 


  Heat being transfered to something
• Which type of surface is good at absorbing and

  emitting radiation?

  black matte
• Which type of surface is poor at absorbing and

  emitting radiation?

  silver shiny
• How do you stop conduction

  use gases or liquids
• How do you stop convection

  Stop gas or liquid particles moving

  (stop convection currents)
• How do you stop radiation

  Use light/shiny materials