Transcript Conduction
Conduction There is NO cold… Only heat. What we perceive as cold is actually low levels of heat. When you hold an ice cube in your hand, cold doesn’t go into your hand; heat energy goes out of your hand into the ice cube. MOTION=HEAT The greater the motion the more the heat energy there is in a solid, liquid or gas. Conduction Energy transfer happens between molecules or atoms when they come in contact. http://www.wisconline.com/Objects/ViewObject.aspx?ID=SCE 304 Investigation Today we are going to investigate conduction through a material. Prediction: Step 1 Aluminum vs. Steel-Which one will conduct more heat? Why do you think that? Liquid-Crystal Temperature Strip The crystals sealed inside turn color when they reach a certain temperature. Different crystals produce their color at different temperatures. Below 30⁰ C = No color Above 36⁰ C= No color Between 30-36⁰ C=light up with color Data Acquisition: Step 2 Discuss: How will you collect data? What makes sense? Making Sense: Step 3 Discuss using Paraphrase Passport: 1. What happened when the metal bars with temperature strips were placed in hot water? 2. How did heat get from the hot water to the temperature strip far above the water level? 3. Did the metals conduct heat? Which metal is a better conductor? Reflection: Step 4 On your own write the answer to this question: The Sun shines on Earth and the air gets warm. How do you think this happens? Conduction in our Atmosphere Conduction is one way energy transfers to the atmosphere. When air molecules come in contact with hot surfaces, they receive energy and get hotter. There is more to the picture… There is a even more important way heat energy enters the atmosphere. It is called reradiation. All matter radiates energy. It is one of the great truths about nature. Hot matter radiates more energy than cold matter. Re-radiation Radiation Conduction Radiation Re-radiation What happens to reradiated energy? Most reradiated energy in not visable. It is infrared radiation. Infrared radiation is absorbed by water and carbon dioxide molecules in the atmosphere. The energized water and carbon dioxide molecules then transfer their energy by conduction (contact) to the oxygen and nitrogen molecules in the air to heat the whole atmosphere. StudyJams!!! • http://studyjams.scholastic.com/studyjams/ja ms/science/energy-light-sound/heat.htm