1. Temperature, Thermal Energy and Heat EQ: How can heat be transferred from one place to another?

2. Temperature The weather report says that today’s high temperature will be 45 degrees and it will be sunny What should you wear? A heavy coat? A hoodie? T-shirt and shorts? Pajamas? What you decide depends on what 45 degrees means.

3. Temperature You don’t need anyone telling you at this point in your life that hot means higher temperatures, and cold means lower temperatures. But when scientists think of high and low temperatures, they aren’t thinking about the words hot and cold Instead, they think about particles of matter in motion.

4. Temperature All matter is made of tiny particles. Particle: any one of the very small parts of matter (such as a molecule, atom, or electron). These particles are always moving even if the matter they make up is sitting still. The energy of motion is kinetic energy. This means that all particles of matter have kinetic energy. The faster the particles move, the more kinetic energy they have. Temperature is the measure of the average kinetic energy of the individual particles of matter. The faster the particles move, the higher the temperature The slower the particles move, the lower the temperature

5. Temperature Which has the higher temperature? The hot cocoa or the cold glass of chocolate milk? Which has a greater average kinetic energy? What would happen to the chocolate milk’s kinetic energy if it is heated? What would happen to the hot cocoa’s kinetic energy if several ice cubes were added?

6. Thermal Energy and Heat Different objects at the same temperature can have different energies. To understand this, you have to understand thermal energy and heat. They are not the same thing. Temperature, thermal energy and heat are related, but they are all different

7. Thermal Energy The total energy of all the particles in an object. It depends on the number of particles in an object, the temperature of the object(how fast the particles are moving), and the arrangement of the object’s particles.

8. Thermal Energy The more particles an object has at a given temperature, the more thermal energy it has. For example, 1 liter of hot cocoa has more thermal energy than a 0.2L of hot cocoa, because the larger pot contains more cocoa. https://www.youtube.co m/watch?v=f1eAOygDP5s https://www.youtube.co m/watch?v=f1eAOygDP5s

9. Thermal Energy On the other hand, the higher the temperature (or the faster the movement of particles) of an object, the more thermal energy the object has. For example, a 1 liter pot of hot cocoa has more thermal energy than 1liter of cold chocolate milk.

10. Heat Thermal energy that is transferred from matter at a higher temperature to a lower temperature. One misconception is that objects contain heat. Objects do not contain heat. They have a temperature and contain thermal energy. Only when the thermal energy from one object is transferred to another object is it called heat.

11. Heat Heat is thermal energy moving from warmer object to a cooler object. For example, when you hold an ice cube in your hand, the ice melts because thermal energy is transferred from your hand to the ice cube.

12. Temperature, Thermal Energy, Heat TemperatureThermal EnergyHeat Temperature is the measure of the average kinetic energy of the individual particles of matter. Faster movement = higher temperature The total energy of all the particles in an object. More particles = more thermal energy (more is more!) Higher temp = more thermal energy Thermal energy that is transferred from matter at a higher temperature to a lower temperature. Heat always transfers from the warmer object to the cooler object

13. Specific Heat You run across the hot sand toward the water at the beach. But you don’t get more than a toe in the water. Why? It’s too cold! How can the sand be so hot and the water so cold since the sun heats them both?

14. Specific Heat The answer is that water requires more heat to raise its temperature than sand does. When an object is heated, its temperature will rise. But the temperature does not rise at the same rate for all objects. The rate depends on the chemical make up of the object. To change the temperature of different objects by the same amount, different amounts of heat are required.

15. Specific Heat The amount of energy required to raise 1 kg of a material by 1 kelvin (degree) is called its specific heat. A material with a very high specific heat can absorb a great amount of thermal energy without a great change in temperature. On the other hand, a material with a very low specific heat would have a large temperature change after absorbing the same amount of thermal energy.

16. Heat Transfer: Conduction, Convection and Radiation https://www.youtube.com/watch?v=eZkHzc-kuj4 EQ: How can heat be transferred from one place to another?

17. The Transfer of Heat While we tend to use the words temperature, thermal energy and heat synonymously, they do not mean the same thing! Temperature is the measure of the average kinetic energy of the individual particles of matter. Faster movement = higher temperature Thermal energy is the total energy of all the particles in an object. More particles = more thermal energy (more is more!) Higher temp = more thermal energy Heat is thermal energy that is transferred from matter at a higher temperature to a lower temperature.

18. How is Heat Transferred? There are three ways in which heat can move: Conduction Convection Radiation

19. Conduction: Energy Transfer by Contact In the process of conduction, heat is transferred from one particle to another through direct contact. EX: A cold metal spoon in a pot of water on a hot stove The fast moving particles in the water collide with the slower moving particles in the spoon. This causes the particles in the spoon to move faster Heat always flows from warm to cold The spoon becomes hotter. Conduction = Contouchin’

20. Conduction: Energy Transfer by Contact The other side of the pillow Does the pillow cool you off or does your body heat warm the pillow? Why? Other examples: Melting an ice cube in your hand Sitting on a hot fireplace mantle Swimming on a hot summer day How is the heat flowing?

21. Convection: Heat Transfer by Movement Convection is heat transfer by the movement of currents in a fluid Current = moving stream Fluids = liquids and gases Air Water Currents will flow from warm to cool. Direct contact between matter is necessary

22. Convection: Heat Transfer by Movement EX: boiling pot of water When water at the bottom of a pot is heated, its particles move faster (raising the temperature) and farther apart. As a result, the water becomes less dense. Less dense fluids will float to the top, so the heated water rises. The cooler water is denser, so it drops to the bottom. But then the cooler water heats, and rises And the water at the top cools, and sinks This rising and falling of the water (or any fluid) creates a convection current. repeat http://www.schooltube.com/video/679d4 fb85386811734a7/ http://www.schooltube.com/video/679d4 fb85386811734a7

23. Convection: Heat Transfer by Movement Other examples of convection: Wind (uneven heating warm vs. cold air) Magma moving the Earth’s tectonic plates Ocean currents Warm-water: flow from equator to poles Cold-water: flow from poles to equator

24. Radiation: Heat Transfer by Waves Radiation is heat transfer by electromagnetic waves No direct contact is needed EX: You can feel radiational heating from a fire in a fireplace from across the room.

25. Radiation: Heat Transfer by Waves Other examples of radiational heat transfer are: The Sun’s energy heating our atmosphere (and your driveway/pool deck!) Laying out in the sun to get a tan

26. Heat Moves ONE Way If two objects have different temperatures, heat will always flow from the warmer object to the cooler object. When heat flows into matter, more particles are heated, and the thermal energy rises. As the thermal energy rises, the particles start moving faster, so the temperature rises. Heat will flow from one object to the other until the two objects have the same temperature.

27. Heat Moves ONE Way EX: Hot food sitting out cools to room temperature if not eaten quickly. BUT!!! Did the food cool or did the surrounding air warm? Why? In science, there is no such thing as coldness. Instead, the matter grows colder as thermal energy flows from it and transfers to another object/form of matter. Heat transfer occurs only in one direction.

28. Conductors and Insulators Have you ever stepped from a rug onto a tile floor? The tile floor feels cooler. But if you measured their temperatures, they would be the same (room temperature) The difference between them has to do with how materials conduct heat. A material can either be a conductor or an insulator.

29. Conductors and Insulators ConductorsInsulators Transfers thermal heat well Metals such as silver and stainless steel are good conductors A good conductor, such as a tile floor, feels cool to the touch because it easily transfers heat away from your skin. Does not transfer thermal energy well. Non-metals such as: wood, wool, straw, clothes, blankets, air and paper are good examples. They slow the transfer of heat.