Energy

• GPE = gravitaional field strength x mass x height
• GPE: Amount of energy stored in objects when lifted.
• Effiency = useful output enrgy transfer / total input energy transfer OR Effeincy = Usefull power output / total power input
• Effiency: amoint of energy supplied that is transfered usefully
• Specific heat capacity: Amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree celcius
• SHC = Energy transfered / Mass x temp change
• Power: Rate of which energy is transfered
• Power = Energy Trasfered / Time


  Power = Work Done / Time
• Kinetic energy: Energy of an object that moves
• Kinetic energy = 0.5 x mass x speed squared
• Elastic potential energy: Energy stored in an object that can be stretched or compressed
• EPE = 0.5 x spring constant x extension squared
• Non renewable resource: Energy source that will run out
• Renewable resources: Energy source that can be reused over and over again
• Renewable resources:

  • Solar power
  • Biomass
  • Geothermal
  • Wind (turbines)
  • Hydroelectric
  • Wave Power
• Non renewable resources:

  . Gas

  . Coal

  . Oil

  . Fossil fuels

  . Nuclear fuels
• Ways energy can be transfered:

  • Mechanically
  • Electrically
  • Through heating
  • Via infared radiation
  • Via light or sound waves
• Open system:

  Can gain or lose energy to 'outside world'
• Features in houses that can reduce heat loss:

  • Double glazed windows.
  • Walls made of a material with low thermal conductivity
  • Cavity walls
• Advantages of biofules:

  • Renewable
  • Can be used in cars
  • Easy to transport
• What is gravity and what properties affect the strength of gravitational attraction? (3 marks):

  1. Gravity is the force of attraction between two objects.
  2. The mass of two objects affects the force of gravitational attraction.
  3. The distance between two objects affects the force of gravitational attraction.
• Convection:

  Process of transfering heat through air or liquid currents
• Weight = Mass x Gravitational field strength

  W = mg
• Gravitational field strength on the moon is 1.6N/Kg
• Why is it important for medical trials to be double blinded? (3 marks):

  1. To avoid bias by the patients or researchers.
  2. If patient knows they have recieved a drug, they may be more likely to report side effects.
  3. If researcher know who has been given the real drug, they may pay closer attention to those patients.
• What is the specific heat capacity of water?

  4,180J/Kg°c