thermal insulation

• materials that are not good thermal conductors are...

  good thermal insulators.
• what are insulators useful for?...

  reducing heat loss and therefore energy bills. to prevent injuries, to keep something hot or cold.
• how do they prevent or reduce heat loss

  they stop the amount of conduction, radiation or convection
• is air an insulator or conductor

  insulator
• trpping air prevents...


  conduction.
• why?


  if the air cant flow, convection cant take place.
• will a vacuum prevent conduction or convection

  both
• can shiny surfaces reflect radiant heat

  yes, back to where required.
• how can we demonstrate thermal insulation in a practical

  use two different insulators and wrap them around two beakers, leaving the third beaker plain as the control experiment. pour boiling water in the beaker and record the initial temp. record the temp for 15 minutes with 1 minute intervals. design a results table, plot a graph and write a conclusion.
• why is it important to do home insulation

  so that no energy can escape and you can have the best efficiency in terms of cost of resources to keep your house warm.
• what is payback time

  payback time of an insulation method is the amount of time it takes to recover the cost of insulation based on annual savings of the energy bill
• how do you calculate it

  payback time = initial cost/ annual saving
• how do you calculate the profit

  profit = (annual saving x time cost) -- initial cost.
• give examples of home insulators and a brief explanation of what they are

  fibreglass loft insulation because lots of energy loss happens through the roof so this traps air and prevents heat loss. also cavity walls which are double layered wall with a gap in between to prevent conduction. they may both come in oil to protect them and to prevent radiation. also double glazed windows.
• if you add the same amount of energy to a mug of water and swimmung pool, why dont they reach the same temperature

  he mass of the object and the type of material also influence how much the temperature will increase by