Section+2

__Vocabulary__ __Self Check__ Because conductors exchange heat and insulators store heat and thermal energy.
 * __Conduction__:
 * Transfer of thermal energy by collisions between particles in matter.
 * __Convection__:
 * Transfer of thermal energy in a fluid by the movement of warmer and cooler fluid from place to place.
 * __Radiation:__
 * Transfer of energy by electromagnetic waves.
 * __Insulator:__
 * Material in which heat flows slowly in.
 * 1) 1- Expalin why materials that are good conductors of heat are poor insulators.

Because hot air rises, and is less dense.
 * 1) 2- Explain why the air temperature near the ceiling of a room tends to be warmer than near the floor.

It would be a good insulator because the thermal energy wouldn't be forced out.
 * 1) 3-Predict whether plastic foam, which contains pockets of air, would be a good conductor or a good insulator.

The less dense material rises and then at the top it becomes dense, then it sinks only to become less dense again.
 * 1) 4- Describe how a convection current occurs.

The shingles on the house radiates heat caused by the sun, and therefore melts the snow.
 * 1) 5- Think Critically- Several days after a snowfall, the roofs of some homes on a street have almost no snow on them, while the roofs of other houses are still snow-covered. Describe what would cause this difference.

200 W 10 M (long) 10 M (wide) =?s 10 x 10 200 x 100 20,000 W
 * 1) 6- Calculate Solar Radiation- Averaged over a year in the central United States, radiation from the sun transfers about 200 W to each square meter of Earth's surface. If a house is 10 m long by 10 m wide, how much solor energy falls on the house each second?