Topic 6 – Transferring Energy

1. Topic 6 – Transferring Energy Heat and Temperature

2. Let’s see what you remember…. • Describe what happens to the volume of solids, liquids and gases as they warm and cool.

3. Substances expand (increase in volume) as they warm. Substances contract (decrease in volume) when they cool. Watch expansion and contraction video

4. Use the particle model of matter to describe, in detail, what happens to water in a fishbowl that is located in a sunny window. (Keep volume and evaporative cooling in mind).

5. An increase in temperature caused water particles to move faster. Some of those near the surface may gain enough energy to evaporate into the air, decreasing the water level in the fish bowl.

6. Vocabulary for topic 6 • RADIATION • the transfer of energy in the form of electromagnetic waves

7. ELECTROMAGNET RADIATION (EMR) • energy that is transferred in the form of electromagnetic waves

8. THERMAL CONDUCTION • the direct transfer of thermal energy from one particle or object to another through contact and collision

9. HEAT INSULATORS • materials that slow the transfer of conduction of thermal energy from one object to another

10. CONDUCTORS • materials that increase the efficiency of heat conduction or the transfer of thermal energy form one object to another

11. FLUIDS • materials (liquids or gases) that lack a definite shape and can flow from one place to another

12. CONVECTION • a process by which a warm fluid moves from place to place carrying thermal energy

13. CONVECTION CURRENT • continuous circulation of a fluid (either a liquid or gas), in which thermal energy is transferred from hotter, less dense fluid to colder, more dense fluid

16. RADIATION • When you sit in front of a fire, you feel warmed by radiant energy. When someone stands between you and the fire, you feel cold again. Explain why this happens. Draw and label a diagram to illustrate your explanation.

17. Radiant energy travels as waves. When someone stands between you and the energy source, the waves are blocked and they cannot reach you. This is why you no longer feel the warmth of the fire. • Diagram:

18. Why are white or light-coloured clothes recommended for hot, sunny locations?

19. White and light-coloured clothes do not absorb as much thermal radiation from the Sun as dark-coloured clothes.

20. Why did the Apollo astronauts wear shiny suits on the moon?

21. The Apollo astronauts wore shiny suits on the Moon to reflect infrared radiation from the Sun.

22. Explain how insulation between the outer and inner walls of a home helps to reduce thermal energy transfer.

23. Insulation that is placed between the outer and inner walls of a home stops radiant energy from traveling between the inside and outside of the home.

24. Explain how a reflective film on windows helps to keep a home cool in the summer but warm in the winter.

25. In the winter, the reflective film helps to radiate thermal energy back into the home. In the summer, it reflects the Sun’s radiant energy away from the home.

26. CONDUCTION • On a cold winter day, why would an iron post in a park feel much colder to the touch than a wooden bench?

27. The iron post would feel much colder than the wooden bench because iron is a better thermal conductor than wood. If you touched the two objects, the iron post would conduct heat away from your hand much faster than the wooded bench does.

28. Potatoes cook from the outside in. • Why does a small potato cook faster than a large potato?

29. Since the thermal energy of the oven conducts through a potato from the outside in, a small potato cooks faster because there is less distance for the thermal energy to travel to reach the middle of the potato.

30. Why does sticking a metal skewer through the middle of a potato make it cook faster?

31. Sticking a metal skewer into the middle of the potato makes it cook faster because the metal skewer conducts heat into the middle of the potato.

32. A metal spoon is used to stir a pot of hot soup. Draw three diagrams to show the behaviour of the particles in the spoon. Write captions to help explain what each diagram illustrates

33. In general, the idea is that thermal energy is conducted from the soup to the handle of the ladle until the entire ladle is warm to the touch.

34. Convection • Sea and land breezes are convection currents that occur in nature. Warmer air rises and cooler air moves in to take its place. • During the day, the land heats up faster than the sea. The warmer air above the ________ rises. This allows the __________ sea air to move in, causing a sea breeze. In the space below, draw and label a diagram of the air currents during a hot, sunny day by the sea.

35. During the day, the land heats up faster than the sea. The warmer air above the land rises. This allows the cooler sea air to move in, causing a sea breeze.

36. During the night, the land cools faster than the sea. The warmer air above the __________ rises. The cooler air over the __________ moves in to take its place, creating a land breeze. In the space below, draw and label a diagram of the air currents during a night by the sea.

37. During the night, the land cools faster than the sea. The warmer air above the sea rises. The cooler air over the land moves in to take its place, creating a land breeze. • WHAT IF THE LAND AND THE SEA WERE THE SAME TEMPERATURE?