HEAT 11.2 Slide 2 Chapter Eleven: Heat 11.1 Heat 11.2 Heat Transfer Slide 3 Chapter 11.2 Learning Goals Compare and contrast various methods of heat transfer. Differentiate between thermal conductors and thermal insulators. Explain what it means when objects are in thermal equilibrium. Slide 4 Investigation 11B Key Question: What is the identity of an unknown metal sample? The Specific Heat of a Metal Slide 5 11.2 Heat transfer Thermal energy flows from higher temperature to lower temperature. This process is called heat transfer. There are three ways heat flows: heat conduction, convection, and thermal radiation. Slide 6 11.2 Heat transfer Heat conduction is the transfer of heat by the direct contact of particles of matter. Conduction occurs between two materials at different temperatures when they are touching each other. Where is the heat energy conducted to and from in this system? Slide 7 11.2 Heat transfer Thermal equilibrium occurs when two bodies have the same temperature. No heat flows in thermal equilibrium because the temperature is the same in the two materials. Slide 8 11.2 Thermal conductors and insulators Materials that conduct heat easily are called thermal conductors and those that conduct heat poorly are called thermal insulators. Is a down coat a conductor or an insulator? Slide 9 Slide 10 11.2 Convection Convection is the transfer of heat through the motion of matter such as air and water. The hot water at the bottom of the pot rises to the top and replaces the cold water. Slide 11 11.2 Convection Convection is mainly what distributes heat throughout a room. Slide 12 11.2 Thermal radiation Heat from the Sun is transferred to Earth by thermal radiation. All the energy the Earth receives from the Sun comes from thermal radiation. The higher the temperature of an object, the more thermal radiation it emits. Slide 13 11.2 Thermal radiation Thermal radiation is also absorbed by objects. The amount of thermal radiation absorbed depends on the surface of a material. Dark surfaces absorb most of the thermal radiation they receive. Silver or mirrored surfaces reflect thermal radiation. Slide 14 11.2 Heat transfer, winds, and currents A thermal is a convection current in the atmosphere. When a surface, like a road absorbs solar radiation, it emits energy as heat. The warmed air molecules gain kinetic energy and rise. Colder air is forced aside and sinks. Slide 15 11.2 Thermal radiation There are giant convection currents in Earths atmosphere. The global wind patterns and Earths rotation also cause surface ocean currents to move in large circular patterns. Slide 16 Investigation 11C Key Question: Can the mass of an object be determined without the use of a balance? Mass Determination Slide 17 Needed: Efficient Buildings Green building design is the term used to describe architecture that is energy-efficient and environmentally friendly.