Grade 7 Science

1. Grade 7 Science Unit 2: Heat Chapter 6: “Heat is transferred from one place to another by three different processes.”

2. Heat Transfer Heat transfers from a hot object to a cold object. http://www.youtube.com/watch?v=o3gN9wI_w64

3. Three types of Heat Transfer... • Conduction • Convection • Radiation

4. 3 Types of Heat Transfer

5. 1. Conductionp.176 • The transfer of thermal energy that occurs when warmer particles come in contact with cooler particles and transfer energy to the cooler particles.

6. Conduction • Occurs when the particles in an object vibrate in place but collide with neighbouring particles passing kinetic energy to them. • The particles do not leave their original position.

8. http://www.youtube.com/watch?v=w_IbPRNZ6ho • Conduction occurs in most solids. Stainless Steel Sides Copper Bottom

9. Ice Packs

10. 2. Convectionp.177 • Occurs when warm fluids move from one place to another carrying heat. • Occurs in liquids and gases.

11. When air warms, the particles gain energy, spread out, become less dense and rise. As it cools, the particles lose energy, get closer together, become more dense and sink. Convection Currents

12. http://www.youtube.com/watch?v=xq1Q5DwfVNU

13. 3. Radiation • Occurs when electromagnetic waves carry energy from a source to another object. The object absorbs the energy of the electromagnetic wave.

14. There are no particles involved. • The waves can travel in a vacuum. http://www.youtube.com/watch?v=YXZcnumnLIo

16. The three types of heat transfer, conduction, convection and radiation, can occur at the same time. For Example...

18. In class work

19. Core Lab Activity Activity 6-1D “Absorb That Energy” Page 184

20. Radiant energy can be...P.183 1. Reflected Shiny, smooth, light-colored surfaces.

21. http://www.youtube.com/watch?v=_v5dfoyXTuE 2. Absorbed Dull, rough, dark-colored surfaces. Object will become warmer.

22. 3. Transmission The radiant energy passes through. Ex. Plastic, glass, paper, etc.

23. Absorption Reflection The Microwave Transmission

24. Activity 6-1 CPage 182 Energy Transfers and Home Heating Systems

25. In class activity • Reading check questions p.185 • #1-3 • Terms assignment

26. Home Heating Technologiesp.185 1. Wood Stove • Efficient radiators due to the black color.

27. 2. Electric Heaters

28. 3. Oil Furnace • Air is drawn into the furnace and heated and fans would blow the warm air through the ducts into the rooms.

29. Forced-air furnace

30. 4. Hot Water radiation • Water carried in a system of pipes can be used instead of air.

31. 5. Air to Air Heat Pump • Can be used to cool the home in the summer and heat the home in the winter. Heat is exchanged with the outside air.

32. 6. Geothermal • Heat is exchanged with the ground. • In the summer, heat is pumped into the ground and in winter it is pumped up from the ground.

33. Geothermal

34. 7. Solar • Converts light energy to electrical energy.

35. Solar Panels

36. In class activity • Check you understanding questions p.191 • Terms assignment

37. Core stse “Heat Pumps: An Alternative Way to Heat Homes”

38. 6.2 p.192 Conductors and insulators

39. Conductors vs. Insulators Conductors • Allow heat transfer • Ex. Metal (some metal are better than others) Insulators • “Prevents” heat transfer • Ex. Wood, plastic

40. Uses of Conductors Cookware p. 194

41. Use of insulatorsp.196 Animal Fur Thermos

42. Fibreglass • The evolution of insulating materials: • Straw, sawdust, seaweed, newspaper, fibreglass, and foam insulation. The foundations of many homes in the Atlantic provinces were insulated with straw or seaweed. Sod • Materials that are very poor conductors of heat.

43. In class work • Wild, weird, wonderful p.2.4 • Terms assignment • STSE finish up • Questions

44. 6.3 p.206 Temperature vs Heat

45. Heat vs. Temperature Heat is the energy which is transferred from hotter substances to colder substances. It is the sum total of the energies of the particles in a substance. (Thermal energy) • Temperature is a measure of how hot or cold something is. • The average kinetic energy of the particles in a substance. http://www.youtube.com/watch?v=wTi3Hn09OBs

46. http://www.youtube.com/watch?v=yxBTEMnrZZk Heat *Depends on the number or amount of particles present. Temperature * Depends on average kinetic energy. Not the amount of particles. 1+2+3+3+2+4+2+5+2+2 = 26J 26 ÷10 = 2.6 ˚C 3 2 4 2 2 3 1 2 5 2

47. Both containers of water have the same temperature because temperature depends on the average kinetic energy. • Both containers of water have a different heat content because heat depends on the number of particles present.

48. True or false? • Does “cold” travel to warm objects cooling them off? • For example: Does a cold drink placed on the table in a warm room get warmer because the “coldness” is being transferred to the warmer surrounding air? • In fact, the drink warms because the heat is transferred from the surrounding air to the drink.

49. Absorbing and Losing heatp.209 • Adding the same amount of heat to two different substances of the same mass will not cause both to increase to the same temperature. • The size of the temperature increase depends on the type of substance.

50. Specific heat capacity • The amount of heat needed to raise the temperature of 1.00 g of the substance by 1.00˚C. http://www.youtube.com/watch?v=caoneXrvp9k