Starter Stick in the ‘Types of Thermal Transfer’ sheet in your book and start to complete the table.

Conduction Convection Radiation   Conduction Convection Radiation Solids  Yes No Liquids  Not well Yes Not main method Gases Not well  Vacuum  No Infra Red Radiation Note: Matt black surfaces are good absorbers and emitters

How is thermal energy transferred  Vibrations and collisions between particles & free electrons. Hot, less dense fluid rising and taking thermal energy Infra Red Radiation – electromagnetic waves Best insulator Why? Vacuum No particles to collide / vibrate No particles to move taking energy with them. Shiny silver surface – poor emitter and absorber of IR. Other insulators  Trapped air – particles are far apart so don’t conduct Non-metals – no free electrons.  Stoppers / lids to prevent hot air rising out of a container removing heat energy.

5 mins Now correct your HW on the vacuum flask using what we have just discovered.

Homework Complete the Fleece Experiment Sheet. For question 3 you need to write out a new method to include all your extra ideas to improve the experiment. Due in Friday

Lesson Aims To be able to explain why sweating is useful to us as a way of cooling down. To explain how sweating cools us using the particle model to help.

Be careful… Evaporation is NOT the same as boiling Lesson Aims: Be careful… Evaporation is NOT the same as boiling What’s the difference?

Evaporation Lesson Aims: Faster particles near the surface have enough energy to escape Slower particles remaining take in heat from the surroundings. Particles move faster and those near the surface have enough energy to escape.

Evaporation Lesson Aims:

Sweating Lesson Aims: When you sweat, droplets of liquid sweat are deposited onto the surface of the skin. As the sweat evaporates, you cool down. You cool down because the sweat draws heat energy from your body in order to change state from a liquid to a gas (evaporate).

Demonstration Lesson Aims: Aim: To find out how evaporation effects the rate that something cools. Diagram: Method: Describe what was done. Results: From the data logger we could see that the bottle with the dry / wet paper towel around it cooled faster. Conclusion: Explain using the particle model, evaporation & cooling why this happens.

Evaporation Explain why a puddle will disappear on a hot day Lesson Aims: Evaporation Explain why a puddle will disappear on a hot day

Lesson Aims: Rugby In the recent six nations, when the England players came off the pitch during the match, they were given a long, thick coat to wear which had a silver lining. Using your knowledge of heat transfer by conduction, convection, radiation and evaporation, explain why they do this to prevent muscle damage.