Topic 3

• A system that experiences no net change in its total energy when energy transfers occur within it.

  Closed System
• The law that energy can be transferred, stored or dissipated but never created or destroyed.

  Conservation of Energy
• The ratio of useful output energy transfer to total energy input. It can never exceed 1 (or 100%), due to the conservation of energy.

  Efficiency
• The application of a lubricant (such as oil) to reduce the friction that acts between surfaces. This may improve the efficiency of a system.

  Lubrication
• A measure of how good a material is at conducting heat. The higher the value is for a given material, the higher the material’s rate of energy transfer via condition will be.

  Thermal Conductivity
• The application of a material that reduces the amount of heat that is transferred from the system in question, to its surroundings.

  Thermal Insulation
• The transfer of energy by a system, to directly serve the purpose of the system.

  Useful Energy Transfer
• The transfer of energy by a system to a form that doesn’t directly serve the purpose of the system.

  Waste Energy Transfer