2.3 Transfer of Energy as heat can be controlled. Helpful animations http://www.wisc-online.com/objects/ViewObject.aspx?ID=SCE304

Heat Say it 3 times. The fire heats up the hotdog. My definition: The flow of energy from a warmer objects to a cooler object Student definition: Energy moves to colder things. Examples: ?

Energy moves as heat in three ways: Conduction Convection Radiation

Conduction The process that moves energy from one object to another when they are physically touching. Ex, metal spoon is in a cup of hot cocoa. Ex, any physical contact with anything (That’s Hot!)

Controlling the Heat? *Conductors- Materials that transfer energy easily Ex. -Iron or metal pots and pans (The handles of pot and pans are plastic to stop the energy transfer) Insulators- are poor conductors (they do not transfer energy easily)

Specific Heat? Def-The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius. -All materials have a certain amount of energy they can absorb before increasing their temperatures.) Water has a high specific heat. Iron has the lowest specific heat.

Controlling the Heat (continued) Insulators- are poor conductors (they do not transfer energy easily) Ex. wood, paper, Plastic foam, thermos, Keeps drinks cold or hot.

Convection The process that transfers energy by movement of particles within a liquid or gas. Process –> (When cooler – denser particles replace the warmer – less dense particles)

Examples of Convection Keeping houses warm Air outside in our atmosphere. Water molecules move to heat a pot of water

Radiation The energy travel as Electromagnetic Waves such as: Visible light, Microwaves, Infrared Light. All things emit radiation – release energy to their surroundings. (Even People!) Major source of Electromagnetic Waves is the sun Things that absorb energy from the sun. Air, Concrete, Sidewalks..etc

Polar bear’s skin/fur are very good insulators- Polar bears have several layers of insulation to keep their body heat in.

Warmest clothes are better insulators. Ex. Wool Your Clothes do the same for you. Your body heat is trapped by the cloth. (keeping you nice and warm.) Warmest clothes are better insulators. Ex. Wool

*Keeping cocoa hot in a Thermos - this is an insulator A Thermos keeps liquid warm because it keep the energy from flowing out of the container.

Heaters or fireplaces help keep your houses warm Heaters or fireplaces help keep your houses warm. Insulation within the walls of your house help keep the energy inside the house.

Helpful website http://teachertube.com/viewVideo.php?video_id=159713 http://www.wisc-online.com/objects/ViewObject.aspx?ID=SCE304 http://teachertube.com/viewVideo.php?video_id=159713