Week 11 Lesson 4 Presentation 4

Objectives Be able to describe how thermal radiation is controlled in everyday circumstances Explain how a vacuum flask can minimise all types of heat transfer Use ideas of heat transfer to design a house that is energy-efficient

In very hot countries, people paint their buildings white In very hot countries, people paint their buildings white. Why do they do this? Try to explain using the idea of thermal radiation

After exercising for a long time your body can cool down very quickly when you stop. Long distance runners are given a silver ‘space blanket’. Why is it silver? Again, use the idea of Thermal Radiation to explain

During re-entry to the atmosphere the bottom of the Space Shuttle gets very hot. Why is it painted black?

What features does a vacuum flask have that stop all 3 types of heat transfer; Conduction, Convection and Radiation?

Slows down heat loss by radiation Stops heat leaving by convection to the open air Stops heat leaving by conduction because there are no particles to conduct Stopper Vacuum between inner and outer wall Silvered inner and outer wall

The Eco-House Design a house that will be as energy-efficient as possible. Use the ideas that we have learnt on different types of heat transfer (conduction, convection and radiation) Try to think of some natural materials that can be used instead of artificial ones. E.g. Soil makes a very good insulator!!