Summary of This Week’s Lab Conductometer Thermal Expansion Convection

Conductometer View the Video -Order from best to worst conductors: Copper Aluminum Brass* Stainless Steel* Nickel * alloys

Thermal Expansion Ball and Ring Lab - View the Video _____________– when molecules are heated Molecules move further apart and take up more space Objects get bigger _____________ – when molecules cool down Molecules move closer together and take up less space Objects become smaller PBS activity

Everyday Examples Bridges have “teeth” or expansion joints Concrete sidewalks have spaces or grooves Exception to the rule: between 32 and 39 water _________ and expands Ice is less dense than water and floats

Convection Heat transfer caused by ____________ differences Liquids and gases Hot gases or liquids- ________because it’s less dense Cold gases or liquids- ________ because it’s more dense

Convection Look at the following site and copy down the picture of the heater- mark the heat flow with 2 different colored pens/pencils http://www.stovesonline.co.uk/stove-heat-distribution.html View the animation

Overall summary Heat is transferred in 3 ways: _____________ It travels from ___________ to ____________ places It is measured in calories. Temperature change = Final Temperature – Initial Temperature Heat = Volume X Temperature change

CONDUCTION Heat transfer by contact/collisions Happens in ______ Better in high density objects

Convection Hot air/water is ______ dense and will ______________. Cold air/water is ______ dense and will ___________. This results in convection _____________.

Radiation Doesn’t require a medium (solid, liquid or gas) Can happen through outer space or empty space (a vacuum) Energy travels as light wave and some of it is then converted back to heat