Insulators and Conductors Review From Last Class l

Insulators and Conductors

Review From Last Class… l l l l What colors and materials best absorb radiant heat? What colors and materials best reflect radiant heat? What is it called when the radiant heat goes directly through the object instead of being absorbed or reflected? What is the largest source of energy on Earth? How does the Earth stay warm? How do plants use the sun’s energy? What technology powers your calculators (specific name)?

Radiant Heat Demo l l l You will have 15 minutes to wrap up the graphing and conclusion questions for the Radiant Heat Demo from yesterday’s class If it is not completed in this time it will be homework. Notes on radiant heat will be passed out as well

Conductors and Insulators l l Conductor: any material that allows heat to be transferred easily Insulator: any material that is not a good conductor of heat

Why Insulate? l l Insulators can be used to prevent heat transfer between objects- to keep hot things hot, or cold things cold For example: in the winter you wear coats and warm clothing to keep your body heat in; your house contains insulation in the walls and roof to keep heat in

Insulators l l l Thermal insulators work by trapping air around and object If the object is hot, thermal insulation prevents the heat from escaping the object, keeping it warm If the object is cold, it prevents the outside heat from mixing with the object keeping it cool

What makes a good insulator? l l Less dense materials are better insulators (atoms are more spread outharder to pass energy) Objects that reflect radiant heat are also good at insulating (reflect heat away keeping insulated material cold, or reflect heat back onto warm objects)

How do I know it’s a good insulator? l l Thermal Conductivity: The rate at which a material conducts heat; objects with low thermal conductivity are best at insulating R-Value: The R-value of a material is its resistance to heat flow and is an indication of its ability to insulate. It is used as a standard way of telling how good a material will insulate. The higher the R-value, the better the insulation. http: //www. school-for-champions. com/science/thermal_insulation. htm#. Vy. NFBG 5 GTTo

Thermos Project l l l Solo or in pairs Must create a “thermos” to keep 250 m. L of hot water warm Research properties of materials, design and construct a thermos as well as an Advertising Pamphlet for your product

Thermos Requirements l l l Must be able to hold 250 m. L of water Must NOT contain any heating device Must NOT contain any part of a commercial Thermos flask must be easily portable must have a lid that is able to open (to pour liquid in) Must contain the plastic tube provided in order to insert a thermometer for testing.

Pamphlet Requirements l l One 8. 5 x 11 size piece of paper Must follow the format below: Name of Thermos Picture of Thermos Slogan for Product Labelled crosssectional diagram of the inside Description of materials used and other features Product Warranty Name of Company Contact Info

Other Details l l l Due date is Wednesday May 11 th Presentation will be “Dragon’s Den” style; we will have guest evaluators that will come in and assess your thermos/design/marketing technique 2 -3 classes will be provided to do research/work on pamphlet; construction and materials will not be provided