7th Grade Science

November 27th 2012

Objectives

• Identify how thermal energy transfers until temperatures reach the same temperature

• Identify common types of materials that transfer energy

Warm-up

• Without using your notes or book, summarize the 4 parts of the kinetic molecular theory and predict and draw (particles of) how an ice cube changes from a solid state to a gas state when left on the counter overnight

How does thermal energy travel?

• When a warm object is brought to near a cooler object, thermal energy will be transferred from the warmer object to the cooler one

• Or from a higher temperature to a lower temperature

Thermal Energy

• Transfers from a warm to a cool temperatures until the temperatures are the same and reach equilibrium

• Think of an ice cube in room temperature water

Heat

• The movement of thermal energy from a substance at a higher temperature to one at a lower temperature is heat

Common materials that transfer energy

• Make a prediction about which of these materials is able to have thermal energy move through it

• Wood• Paper clips• Fabric• Plastic• Rubber • styrofoam• Cardboard• Foil• Keys• pennies

What do we call materials which thermal energy CAN travel through?

• A thermal conductor is a material that allows energy in the form of heat, to be transferred within the material, without any movement of the material itself

Thermal Conductor

• Most metals• Paper clips• Foil• Keys• Pennies

• Why are pan handles made mostly of plastic?

Some examples you can think of as thermal conductors

• 1 minute thinking time

What do we call a material that does not allow thermal energy to move through it?

• An insulator is a material that does not allow a transfer of electricity or thermal energy. Materials that are poor thermal conductors can also be described as being good thermal insulators.

Thermal Insulators

• Wood• Plastic• Fabric • Rubber• styrofoam • cardboard

Some examples you can think of for thermal insulators

• 1 minute thinking time

Short video clips

• http://www.youtube.com/watch?v=maPt__CZ1cY&feature=related

• http://www.youtube.com/watch?v=7rlvyqOhrOc

• http://www.youtube.com/watch?v=0v4OlcmRmvo

• http://www.youtube.com/watch?v=fOT86CoHSQQ

Short Quiz

• Name 2 materials that are good thermal conductors

• Name 2 materials that are good thermal insulators

• Explain why:– Steel is good for making cooking pots– Why insulation in homes is not made from metal

Other resources

• http://www.bbc.co.uk/schools/ks3bitesize/science/energy_electricity_forces/energy_transfer_storage/revise5.shtml

• The physics classroom