1. HEAT TRANSFER Conduction, Convection, and Radiation

2. State Science Standard Students know heat energy flows from warmer materials or regions to cooler ones through conduction, convection, and radiation

3. Objectives Explain conduction, convection, and radiation using terms of heat transfer. Given a scenario involving heat transfer, recognize conduction, convection, and radiation. Compare different materials and their ability to transfer heat. Understand the properties of conductors and insulators.

4. Temperature What are you measuring when you take someone’s temperature? Here is a hint: When we studied the states of matter, we learned that particles speed up as they change from a solid to a liquid, and then to a gas. Temperature is a measure of the average kinetic energy of the individual particles in matter. When you heat a thermometer, the particles in the liquid inside the thermometer speed up and take up more space. The liquid then rises up the tube.

5. Thermal Energy If you were to compare the amount of kinetic energy in a cup of water to the amount of kinetic energy in the Pacific Ocean, which has more energy? Why? The ocean has more kinetic energy than a cup of water because it has more particles that can move. The total energy of all the particles in an object is called thermal energy.

6. Thermal Energy The thermal energy of an object depends on three things: the number of particles in the object the temperature of an object the arrangement of the object’s particles (not going to worry about this one this year) Which one has more thermal energy, a mug of hot cocoa at 75 degrees Celsius or a large pot of hot cocoa at 75 degrees Celsius? Which one has more thermal energy, 100 mL of boiling water or 100 mL of cold water?

7. Heat What does your mom tell you when you leave the front door open on a cold day? Heat is thermal energy moving from a warmer object to a cooler object. Technically, you are letting out the thermal energy during this heat transfer (not letting the cold air in). If two objects have different temperatures, heat will flow from the warmer object to the colder one.

8. Conduction In the process of conduction, heat is transferred from one particle of matter to another without the movement of matter. This is how a pot gets hot when sitting on a stove. The fast-moving particles in the hot electric coil of the stove collide with the slow moving particles in the cool pot. The transfer of heat causes the pot’s particles to move faster. Let’s demonstrate this by passing a gentle push around the classroom.

9. Convection In convection, heat is transferred by the movement of currents within a fluid. Remember density? Is warm air more or less dense than cool air? When you heat water on the stove, the water at the bottom of the pan heats faster than at the top. The water at the bottom becomes less dense and floats to the top. It then cools because it is farther away from the heat source and sinks back to the bottom.

10. Convection This flow creates a circular motion known as a convection current. Cooler water sinks because it is more dense Warmer water rises because it is less dense This creates a convection current

11. Radiation Radiation is the transfer of energy by electromagnetic waves. Unlike conduction and convection, radiation does not require matter to transfer thermal energy. This is why the sun’s energy can reach Earth. It can travel through empty space (no matter required).

12. Conduction, convection, or radiation? You sit by the fire to get warm. As you sit on the beach by the ocean, a wind comes up. You burn your hand when you grab the spoon sticking up out of the soup on the stove. You cook your Totinos pizza rolls in the microwave. Even on a cold, sunny day, the inside of the car feels warm. You take a ride in a hot air balloon.

13. Conductors and Insulators A material that conducts heat well is called a conductor. Would you rather grab a metal spoon or a wooden spoon that has been sitting in a pot of boiling soup? A material that does not conduct heat well is called an insulator. Would you rather wear a down jacket or a sheet of aluminum foil on a very cold day?