Physics - P1.2 - Using Energy

HideShow resource information

P1.2.1 - Forms of Energy

  • Types of energy - light, sound, kinetic, nuclear, electrical, gravitational potential, elastic potential, chemical - last three = forms of stored energy
  • Energy can be transferred from one form to another
  • Any object above the ground has gravitational potential energy
  • Falling object transfers gravitational potential energy -> kinetic energy
1 of 4

P1.2.2 - Conservation of Energy

  • Not possible to create or destroy - possible to transfer it from one form or place to another
  • Conservation of energy - total amount of energy is always the same, applies to all energy transfers
  • Falling object - gravitational potential energy -> kinetic energy
  • Stretching an elastic band - chemical energy -> elastic potential energy
  • Solar cell - light energy -> electrical energy
  • Swinging pendulum - gravitational potential energy -> kinetic energy and back as it swings
2 of 4

P1.2.3 - Useful Energy

  • Machine - something that transfers energy from one form or place to another
  • Energy we get out of a machine consists of: useful energy - transferred to place and form wanted, wasted energy - not usefully transferred
  • Useful and wasted energy eventually transferred to surroundings and make them warm up
  • Energy spreads out - becomes more difficult to use for further transfers
  • Energy often wasted because of friction between moving parts of machine - warms machine and surroundings
  • Friction may be useful - brakes of bike or car
  • Some kinetic energy of vehicle transferred to energy heating brakes
3 of 4

P1.2.4 - Energy and Efficiency

  • Joules (J) - unit for all forms of energy
  • Input energy - energy supplied to machine
  • Input energy = useful energy transferred + energy wasted
  • Less wasted energy = more efficient
  • Efficiency = useful energy transferred by appliance
                           total energy supplied to appliance      X 100
  • Left as a fraction or multiplied by 100 to give %
  • No appliance = 100% efficient - except electrical heater - usefully transfers all electrical energy supplied to heating surroundings
  • Energy transferred through appliance represented with sankey diagram
4 of 4


No comments have yet been made

Similar Physics resources:

See all Physics resources »See all Energy resources »