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# Y7 Wk 36 Heat and heat transfer

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Acep science, term 2, Heat Transfer

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### Y7 Wk 36 Heat and heat transfer

1. 1. Heat and Heat Transfer Pg. 126- 130
2. 2. Heat is more than hot or cold  Heat is:  ENERGY TRANSFER from a higher temperature to a lower temperature.  Energy in the form of heat always flows from HOT to cold. Activity: Look at the picture, in your notebook draw the energy flow from the higher temperature object to the lower temperature object.
3. 3. Textbook page 126, exercise #7  Draw an arrow  to show the direction of energy flow.  Remember, energy flows from HOT to Cold   
4. 4. Measuring Heat  One way of measuring heat is the calorie (cal). * In nutrition, 1 C (a Kilocalorie) is equal to 1000 calories. *  One calorie (cal) is equal to the amount of energy needed to raise the temperature of 1 g of water by 1oC.  Heat is energy flow.  Thermal Energy is the total Kinetic Energy of a substance.  Temperature is the average Kinetic Energy of a substance.
5. 5. Conductor: Metal Wire Heat Transfer Liquid Beaker A = 85oC Beaker B = 15oC  Beaker A has a higher temperature. 85oC  Heat will transfer from Beaker A to Beaker B (by conduction using the metal wire).  Heat will transfer until both beakers are the same temperature.  Beaker B will have MORE THERMAL energy because it has
6. 6. HEAT  How do you touch hot food or other hot items?  Write down materials you use to touch hot items without burning yourself: 1. 2. 3.
7. 7. Conductors and Insulators  Insulators are materials that are poor conductors of heat. These keep objects hot (or cold), but not your hands! Examples: wood, plastic foam, paper  Conductors are materials that transfer heat very well. These objects will transfer heat fast from the object to your hand. Example: Metals
8. 8. Activity Pg. 129, #12 in textbook
9. 9. Heat Transfer  There are 3 types (Conduction, Convection, Radiation)  HEAT is the flow of energy from a higher temperature object to a lower temperature object. VIDEO  please click to listen and watch an online Prezi about the 3 types of Heat Transfer. **Can you explain the last picture in the video?**
10. 10. Heat Transfer 1: Convection  Click the above link to see Convection of a gas.  Convection also works for liquids!  click for the video!  Add Energy (in the form of heat from a higher temperature object). The particles of a substance (gas or liquid) will move faster and spread apart, which makes them less dense. They will rise up. They have more kinetic energy.  When they begin to cool, the particles move slower and move closer together, which makes them denser. They
11. 11. Heat Transfer 2: Conduction  When a higher temperature object is in contact (touching) a lower temperature object, heat will flow from the hotter object to the cooler object.  This is Conduction!  In the photo to the left, which letter demonstrates conduction? A: The burner is in contact with the kettle and the flame.
12. 12. Conduction Continued  This is a polar bear hair.  There is air in the middle. This is a good insulator. This helps to keep the bear warm.
13. 13. Heat Transfer 3; Radiation  Radiation is heat transfer through electromagnetic waves.  There is no direct contact (touching) between the higher temperature object and the lower temperature object.  An example is the SUN. It warms the earth through radiation.
14. 14. Summary of Heat Transfer: Convection of liquid
15. 15. Quiz 1. What is the difference between an insulator and a A conductor has particles that transfer heat quickly. conductor? has particles that do not transfer heat quickly. An insulator 2. What Heatis used to measure heat? unit is measured in calories (cal). 3. If a substance No it may not. It has to have many molecules. Tempera has a higher temperature, does it is the average kinetic energy of a substance. Thermal E also have greater kinetic energy of a substance. thermal energy? total 4. List 3 types of Heat Transfer. Conduction, Convection, and R When two objects of different temperatures are in contact, which conduction. Conduction demonstrate? This demonstrates heat transfer does this transfers heat by two 5. After a period of time, the temperatures of both objects will be th