P3 - Conservation of Energy

• What is the equation for change in gravitational potential energy?


  ∆GPE = m× g ×∆h
• What is the value of g on Earth?

  10 N/kg
• What is the equation for kinetic energy?

  KE = ½ × m× v2
• conservation of energy states that energy cannot be created or destroyed: when there are energy transfers, the total energy does not change
• Which store of energy increases when an object moves upwards?

  Gravitational potential energy
• Which store of energy does a moving object have?

  kinetic
• Which store of energy does a stretched or compressed object have?

  elastic potential
• Which store of energy does a hot object have?

  thermal
• ways that energy can be transferred

  light,sound and heating
• in any wasteful process energy gets dissipated as heat into the surroundings
• unwannted energy transfer can be reduced by lubrication and thermal insulation
• The thicker the walls, the slower the rate of cooling
• efficiency = (useful energy transferred by the device) / (total energy supplied to the device)
•  examples of renewable energy sources

  Bio-fuel, wind, hydroelectricity, the tides, the Sun
•  non-renewable energy sources

  Fossil fuels, nuclear fuel