Thermal Energy Transfer 6th grade science Whitworth
Temperature Temperature measures the average kinetic energy of the particles in a substance. The more KE the higher the temperature. How HOT or COLD an object is.
Heat Transfer and Fact Heat is the transfer of thermal energy between substances at different temperatures. When objects are heated, their particles move faster and take up more space so they EXPAND. When heat is released from an object, the particles slow down and CONTRACT.
Important Temperatures 0 C = 32 F (Freezing Water) 100 C = 212 F (Boiling Water) 37 C = 98.6 F (Body Temperature)
Temperature Scales
HEAT FLOW: HEAT ALWAYS FLOWS FROM WARMER TO COOLER UNTIL THERMAL EQUILIBRIUM IS REACHED!
Heat Flow Human bodies work differently. We do not reach equilibrium with our environment because our bodies help regulate temperature. We can feel temperature changes though…
Conduction Conduction is the transfer of heat through materials by the direct contact of matter. Dense metals like copper and aluminum are very good thermal conductors. Solids usually are better heat conductors than liquids, and liquids are better conductors than gases.
Conduction Example
Conduction Example
Thermal Insulator A thermal insulator is a material that conducts heat poorly. Heat flows very slowly through the plastic so that the temperature of your hand does not rise very much.
Thermal Conduction
Thermal Conduction
Why does metal feel colder than wood, if they are both at the same temperature? Metal is a conductor, wood is an insulator. Metal conducts the heat away from your hands. Wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal.
Convection Convection is the transfer of heat by the motion of liquids and gases (FLUIDS). Convection in a gas occurs because gas expands when heated and contract when cooled. Convection occurs because currents flow when hot gas rises and cool gas sink. Convection in liquids also occurs because of differences in density.
Water movement Cools at the surface Convection current Hot water rises Cooler water sinks
Weather When hot air rises, the air is replaced by the surrounding cooler, more dense air, which we feel as wind. Convection currents are responsible for weather patterns in the troposphere.
Sea Breezes
Earth’s climate due to convection
Where is the freezer compartment put in a fridge? Cold air sinks Where is the freezer compartment put in a fridge? Freezer compartment It is warmer at the bottom, so this warmer air rises and a convection current is set up. It is put at the top, because cool air sinks, so it cools the food on the way down.
Radiation Radiation is the transfer of heat through electromagnetic waves. Radiation DOES NOT require matter in order to transfer thermal energy!
Radiation There are no particles between the Sun and the Earth so thermal energy CANNOT travel by conduction or by convection. ONLY.... Main source of Earth’s radiation RADIATION ?
Radiation Shiny objects or light colored objects do not absorb radiation as well as dull black objects.