2 Heat Transfer
❖ Heat (thermal energy) always transfers from a system with a ____________
temperature to systems with a _____________temperature.
❖ There are 3 ways for heat to transfer:
❖ Conduction: heat transfer by __________________________________
➢ Objects have to be ________________
➢ Ex. _______________________________________
❖ Convection: heat transfer by __________________ due to ____________ differences
•
Hot air ____________, cold air ________________
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Hot water ____________,, cold water ____________,
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Creates a “____________,” of energy movement
❖ Radiation: heat transfer through ____________,
•
Ex. _______________________
•
Ex. _______________________
Greenhouse Effect:
● Earth’s atmosphere __________ energy from the __________. This is known as the
____________ effect.
● GLOBAL WARMING:
● A world-wide condition with the potential to cause a _______________in sea level and
____________ change.
● Carbon dioxide (CO2) levels in the atmosphere have _______________in the last 150
years.
● Due to the high amounts of CO2 (released from the combustion of fossil fuels);
__________
● Conduction and insulators of heat:
Materials can be classified based on their ability to transfer heat energy:
1. Conductors: _______________heat
•
Includes ALL __________, rocks, __________
2. Insulators: _______________heat transfer
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Includes Styrofoam, fiberglass, ___________, hair/wool, and ___________
What is a double pane window?
Why is hair/fur a good insulator?
Why would Styrofoam be a
good insulator?
Rule of Thumb: the ____________ the molecules are together, the _______________ the
_______________of heat.
● Solids: ___________ conductor; molecules are ____________________(this includes metals)
● Liquids: ___________ conductor; molecules are “___________” and close together
● Gases: ___________ conductor; molecules are ____________________(less direct contact)
Substances change shape due to their change in temperature.
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As a general rule, increasing the temperature of a substance causes it to ____________ this is
called Thermal Expansion. As a substance cools, it _________________.
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Ex. Spacers in metal bridges or concrete highways.
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Ex. “Cracks” in concrete sidewalks.
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Ex. Mercury in a thermometer
Assignment
Conduction, Convection, and Radiation
Identify the method of heat transfer that takes place in each illustration. Write the method of heat
transfer underneath the picture.
1
3
2
4
7
5
6
9
8
Water
boiling in a
kettle
10
11
13
14
12
15
Identify the type of heat
heat transfer (conduction, convection, and radiation) that is occurring in each situation below.
Some situations may have more than one answer, but choose the best choice.
16. The coffee gets stirred with a spoon and the spoon gets hot ____________________
17. The side of a chair facing the fire in the fireplace gets warm. ____________________
18. A decorative lamp contains globs of colored liquid that break off and rise to the top.
______________
19. Warm air rises in a room. ____________________
20. In a swimming pool, the water near the surface is slightly warmer. __________________
21. One end of a copper rod is placed in the flame of a lab burner. Small pieces of wax placed
along the rod melt at progressively larger distances from the flame. _________________
22. Sand getting hot during the day and cooler at night. _______________
23. Black paint absorbs infrared light. ___________________
24. A house burns down. On the house next door, all the vinyl siding is twisted and warped by
heat. ___________________
25. A student holds the back of his hand to an iron to see if it is hot. __________________