reducing unwanted energy transfers

• | lubrication

  • reduces frictional forces
  • friction causes energy to decrease in the system
  • flows easily between objects
• | heating

  • occur by CONDUCTION or CONVECTION
  • when heated, energy is transferred into kinetic energy store of particles which vibrate & collide with each other
  • during these collisions, energy is transferred between the particles’ kinetic energy stores which is known as CONDUCTION
  • if particles r free to move, particles going faster means space between them increases which decreases density
  • bc they can flow, the warmer & less dense region will RISE- energetic particles move away from hot to cold regions which is CONVECTION
• | insulation

  • reduced rate of energy transfer by heating
• | insulation

  • have THICK WALLS with low thermal conductivity = slower rate of energy transfer
  • use thermal insulation liiike…

  1. CAVITY WALLS: inner & outer wall w/ air gap which reduces conduction
  2. LOFT INSULATION: reduces convection currents in lofts
  3. DOUBLE GLAZED WINDOWS: air gap between two sheets of glass to prevent CONDUCTION through windows
  4. DRAUGHT EXCLUDERS: around doors & windows reduces energy transfers by convection
• what do lubricants do?

  reduces friction
• what does insulation do

  reduces rate of energy transfer by heating
• how do you reduce friction?

  use lubricants