Unit C: Heat in The Environment (Pg. 174 – 259)
Chapter 8: Energy Transfer & Conservation (pg. 200 – 227)
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8.1: Thermal Energy Transfer (Pg. 202– 203) & PB (Pg. 152 – 154)
TB 203 & PB 153:
1.
In what direction does thermal energy flow naturally?
TB & PB: Thermal energy naturally flows from a substance with a higher temperature to a substance with a lower
temperature.
2.
Give an example of thermal energy being transferred from one material to another.
TB:
When you hold an ice cube, thermal energy from your hand moves into the ice, causing it to melt.
Also PB # 2:
Warm air inside a house moves through cracks around windows to the cool outside.
3.
Suggest one way (onto slow down the transfer of thermal energy into or out of a substance with the aid of technology.
TB: If you want to keep a sandwich cold, you can place it in the refrigerator in order to reduce the transfer of thermal energy
into it.
3. PB: Name one technology that slows down the transfer of thermal energy. Explain:
PB: A refrigerator slows the transfer of thermal energy. A refrigerator move thermal energy away from the good inside.
4. PB: Key Question: What have you learned about how energy moves between places or objects?
PB: Energy moves from a warmer object to a cooler one, or the other way around.
8.1: Reviewing Energy Transfer: PB (pg. 154)
a) The energy moves from the pan to the uncooked food. This energy will heat and cook the food. The energy will continue
to move until the pan and the food have the same temperature….
b) The energy moves from the person’s warm hand to the glass of water. The water will warm up and the ice will
eventually melt.
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8.3: Conduction (Pg. 206– 207) & PB (pg. 155 – 158)
TB (207) & PB (158):
1.
a) Define “conduction”. Also PB # 1
Conduction: is the transfer of thermal energy through a substance, or between substances in contact, by the collision of
particles.
b) How has your understanding of the word “conductor” changed since you read this section?
Before I read this section, I thought conductors were things that electricity can move through. Now, I know that there are also
thermal conductors that transmit thermal energy.
2.
In your own words, explain how thermal energy is transferred by conduction.
Conduction happens when two substances are touching. The particles of one substance collide with each other or with particles
of the other substance and transfer thermal energy.
3.
List one material that is a good conductor and one that is a good insulator. Suggest one use for each material. Also PB # 3 & 4
Metals are good thermal conductors. They are used in radiators. Wood is a good thermal insulator. It is used in many houses.
PB Pg. 158:
2. Describe in your own words the flow of thermal energy when cooking an egg.
The thermal energy starts in the hot stove top. The particles of the stove run into the particles of the pan. The pan then warms
up. The warm particles of the pan run into the particles of the cold egg. The egg then warms up and cooks.
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8.5: Convection (Pg. 210– 211) & PB (pg. 166-168)
TB ( 211) & PB (167-168).
1.
Explain how thermal energy is transferred through convection.
In convection, particles move from one place to another, carrying thermal energy with them.
2.
Use the particle theory to explain how a convection current starts in a fluid.
A convection current starts in a fluid when some of the particles in a fluid absorb thermal energy. This causes the particles to
move farther apart. That makes the substance less dense, so it rises through the denser surrounding fluid.
3.
Give two examples of convection currents that you might encounter in everyday life. Also PB # 2
a) a teapot being heated on the stove
b) the currents in the air when I turn on the heater.
4.
If you wanted to warm your room using a portable heater, where would you place the heater? Why?
The heater should be placed on or near the floor. As the air nearby absorbs thermal energy from the greater, the air will rise
toward the ceiling and set up a convection current. That will carry the thermal energy through the room. If the heater were
placed near the ceiling, the warm air would just float near the top of the room.
5.
Define “Convection”.
Convection: the transfer of thermal energy from one part of a fluid to another by a circulating current of faster-moving and
slower-moving particles.
PB (167)
1.
Why can convection not take place in solids?
Convection can’t take place in solids because the particles in a solid cannot flow.
2.
Give two examples of convection currents that you might see in everyday life.
a) currents in the air outside
b) boiling water
3.
Key Question: Define convection.
Convection is the transfer of thermal energy from one part of a fluid to another by a circulating current of faster-moving and
slower-moving particles.
PB (168)
1. a) liquids, solids
b) thermal
c) rise, fall, continuous
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8.7: Radiation (Pg. 214– 216) & PB (174 – 178)
TB (216) & PB (177)
1.
List two objects that absorb radiant energy from the Sun. ALSO PB # 1
Two objects that absorb radian energy from the Sun are (our bodies, rocks, and the benches at a baseball field).
2.
List two objects here on Earth that are sources of radiant energy. How can you tell that they emit radiant energy? ALSO PB # 2
TB: Candle flames and incandescent light bulbs are sources of radiant energy here on Earth. You can tell that they emit
radiant energy because they give off light and thermal energy (they glow and feel hot).
3.
TB: Distinguish between the effects of solar radiation on a snow-covered asphalt driveway and a shovelled asphalt driveway.
Snow and ice on a snow-covered asphalt driveway reflect much of the Sun’s radiant energy back into space. The rocks and
water on a shovelled asphalt driveway are less able to reflect the visible light of the Sun. Therefore, a shovelled driveway will
become warmer on a sunny day than an unshovelled driveway.
3. PB: The snow-covered driveway would reflect most of the Sun’s radiation. The snow would be very bright, but would stay
cold. If the snow were shovelled, the dark driveway would absorb more of the Sun’s radiation. It would get warmer…
4.
Why do you suppose bee keepers use white paint and use shiny aluminum lids on their bee hives?
The shiny surface of the aluminum and the white paint reflect radiant energy, keeping the bee hive from becoming too warm.
PB # 4: Some people who keep bees put white paint and shiny covers on the hives. Why might they do this?
They might want to keep the bees cool. The white paint and shiny lids would reflect the Sun’s radiation, keeping the bees cool.
5.
What form of energy do you think microwave ovens use? Explain your reasoning.
Microwave ovens use radiant energy. Microwaves allow food to be heated without direct contact with the heating source, and
they do not require full movement of matter for the energy to be transferred from the heating source to the food.
PB # 5: Key Question: Describe how radiation moves through space.
Radiation travels through space as electromagnetic waves. It travels as visible light from the Sun.
6.
Define:
Radian energy: energy that travels in the form of electromagnetic waves through empty space; includes visible light,
ultraviolet rays, and infrared rays.
a)
b)
Radiation: the transfer of radiant energy by means of electromagnetic waves.
PB 178: 8.7 – Puzzling over Radiation:
Across:
2. electromagnetic
5. radiation
6. ultraviolet
Down:
1. reflect
3. infrared
4. absorb
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8.8: Managing the Transfer of Thermal Energy (Pg. 217– 220) & PB (179 – 185)
TB 220:
2. Why is it important to consider the transfer of energy when building a house?
It is important to consider the transfer of energy when building a house because controlling the transfer of thermal energy
helps to conserve energy resources.
3. Explain why the walls and doors of refrigerators and freezers contain thick slabs of polystyrene foam.
The slabs of polystyrene foam serve as insulators. They reduce thermal energy transfer from the environment into the
refrigerator or freezer.
4. High-quality modern homes are very well sealed:
a) How does this help conserve energy?
The tight seals help prevent air from transferring thermal energy between the building and the environment.
b) What problem may this create?
The tight seal can cause the build up of harmful gases and moisture inside the building.
c) How does an air-to-air heat exchanger overcome this problem and still help conserve energy?
In an air-to-air heat exchanger, the air ducts carrying stale indoor air are in contact with the ducts carrying the fresh outside
air. This allows thermal energy to move between outgoing warmer air and the incoming cooler air, thereby recovering some of
the thermal energy that might be lost to the outside.
5. Describe one way that builders can reduce each of the types of heat transfer in a building.
Builders can reduce conduction by using insulation. They can reduce convection by sealing gaps in the building’s structure.
They can reduce radiation by using low-E glass in windows and doors.
PB 184:
1.
Why do some refrigerators doors and freezer doors have polystyrene foam in them?
Polystyrene is a good insulator with a high R-Value. It will keep the warm air outside the refrigerator from moving inside.
2.
Many high-quality modern buildings are well sealed to conserve energy. Name two possible problems this could create.
a) Trapped moisture can cause mould and make wood not
b) Unhealthy gases can also be trapped.
3.
a)
b)
c)
Key Question: Name a way that builders could reduce energy loss by:
Conduction:
Insulators could keep energy from being lost through conduction.
Convection:
Sealing gaps in a building prevents energy loss through convection.
Radiation:
Energy loss by radiation could reduced by adding shiny radiation barriers.
PB: 185 – 8.8: Investigation Home Energy Loss:
1. d 2. g
3. e
4. b
5. f
6. c
7. a
Chapter 8: Chapter Review (pg. 226 – 227)
1. List three ways in which energy can be transferred. Briefly describe each way.
a) Conduction: During conduction, the particles in matter transfer energy by colliding with other particles.
b) Convection: During convection, moving matter carries energy from one place to another.
c) Radiation: During radiation, radiant energy is transferred by electromagnetic waves.
3. What is unique about the way energy reaches Earth from the Sun?
The transfer of energy from the Sun to Earth does not require the presence of matter, because the energy is transferred by
radiation.
6. How does reducing energy loss from homes demonstrate environmental stewardship?
Reducing energy loss from homes helps us conserve energy resources which reduces our negative effects on the environment.
7. Explain why a down-filled jacket loses its insulating ability when it gets wet.
Down-filled jackets contain many air-filled spaces. The air is a good insulator. When the jacket gets wet, the feathers clump
together and it loses its insulating ability because it no longer has these air-filled spaces.
12. A well-insulated home is more comfortable and costs less to heat:
a) What are some areas of your home where energy might be lost?
Energy may be lost in the areas around windows and doors.
b) What can be done to reduce this loss?
To reduce this loss, weather stripping can be added to these areas.
c) What are the benefits of reducing energy loss?
Reducing energy loss makes the home more comfortable and helps to save money on energy bills
16.
a) What might be some deterrents to having a green roof?
Green roofs are more expensive than conventional roofs, and they require more maintenance.
b) Suggest how these deterrents might be overcome.
Educating people about the advantages of green roofs might make them more likely to use them.
17.
a) What are some of the disadvantages to having airtight buildings?
If no air can get into or out of a house, moisture and harmful gases can build up inside the house.
b) How can these problems be solved?
One way to solve the problems is to ventilate the building better. An air-to-air heat exchanger can reduce thermal energy loss
while still providing fresh air.
19. Answer the key question: How does the transfer of energy affect natural and human-built environments?
The transfer of energy drives natural processes. Thermal energy from within Earth helps rocks and minerals form. Uneven
heating of the air at Earth’s surface can produce convection currents in the air. Wind and thunderstorms are the result of
these convection currents. Radiant energy from the Sun provides energy to warm Earth. Humans have invented technologies
to manage the transfer of thermal energy. We use refrigerators and freezers to keep food cold, and heaters to keep spaces
warm. Building designers select materials that reduce unwanted energy transfer and keep buildings warm or cool, and
comfortable.