Bellringer The three pictures all show examples of energy transfer. Answer the questions about what happens in each picture, and identify how the heat goes from one object to another in each case. Why is it a bad idea to drink hot cocoa out of a tin cup? Explain the energy transfer on the atomic level.

Bellringer, continued 2. What happens to your hand when you place it above a lighted candle? (Assume you are not touching the flame. Explain the energy transfers on the atomic level. Hint: Remember that warm air rises.) 3. When you sit near a fire, you can feel its warmth on your skin, even if the air is cool. Does this sensation depend upon the fact that warm air rises?

SPS7.b Investigate molecular motion as it relates to thermal energy changes in terms of conduction, convection, and radiation.

EQ: How does energy change differ in conduction, convection, and radiation?

Methods of Energy Transfer How does energy transfer happen?

14-2-1 Methods of Energy Transfer, continued Conduction occurs between objects in direct contact.

14-2-2 Methods of Energy Transfer, continued thermal conduction: the transfer of energy as heat through a material

14-2-3 Methods of Energy Transfer, continued Convection results from the movement of warm fluids.

14-2-4 Methods of Energy Transfer, continued convection: the movement of matter due to differences in density that are caused by temperature variations

14-2-5 Methods of Energy Transfer, continued convection current: any movement of matter that results from differences in density; may be vertical, circular, or cyclical

Conduction and Convection

14-2-6 Methods of Energy Transfer, continued Radiation does not require physical contact between objects.

14-2-7 Methods of Energy Transfer, continued radiation: the energy that is transferred as electromagnetic waves, such as visible light and infrared waves

14-2-8 Methods of Energy Transfer, continued All hot objects give off infrared radiation.

14-2-9 Methods of Energy Transfer, continued Radiation does not involve the movement of matter across space and is the only way that energy can be transferred through a vacuum.

14-2-10 Conductors and Insulators A conductor is a material through which energy can be easily transferred as heat.

14-2-11 Conductors and Insulators An insulator is a material that transfers energy poorly.

14-2-12 Conductors and Insulators, continued Heat energy is transferred through particle collisions. Therefore more dense materials are better conductors.

14-2-13 Conductors and Insulators, continued Gases and plastics are very poor heat conductors and metals are good conductors.

14-2-19 Specific Heat, continued Heat can either raises an object’s temperature or changes the object’s state, but not both at the same time. .