Ch
Name:_ANSWER KEY__________ Ch. 10 Review Questions
1. What is the coldest temperature possible? What is this in Celsius, Fahrenheit and Kelvin.
Absolute zero = -273 C, -459.4 F, 0 K
2. Why do you think heating a full pot of soup on the stove could cause the soup to overflow?
The volume of matter increases when it is heated, so when the soup is heated it expands out of the pot.
3. Why does a tile floor feel colder than a carpeted floor?
Tile has a higher thermal conductivity than carpet and quickly conducts the heat away from your feet leaving them feeling cold
4. Why do many metal cooking utensils have wooden handles?
Metal utensils have wooden handles so that heat is not conducted up the utensil to your hand. (Wood is not a good conductor, it is an insulator)
5. Explain what happens in terms of energy when you put a can of soda at room temperature into a cooler of ice water.
When you put a can of soda in ice water, energy is transferred from the soda to the ice water. This decreases the temperature of the soda and increases the energy of the ice water.
6. Why do you think a down-filled jacket keeps you so warm? Explain.
A down jacket is a good insulator and prevents heat from leaving your warm body.
7. In a hot air balloon, air is heated by a flame. Explain how this enables the balloon to float in the air.
When the flame is on it heats the air in the balloon making it less dense. This less dense air can then float in air outside the balloon which is cooler and more dense.
8. Why are sidewalks constructed with spaces between the sections?
The spaces allow the sidewalk to expand in warm weather without cracking.
9. Explain why two substances can have the same temperature but different amounts of thermal energy.
Thermal energy is the total KE of the particles in an object and temperature is the average KE of the particles in a object. If you have more particles (a bigger object) than you have more total KE.
10. Explain how water behaves differently than most substances when it freezes.
Water expands when it freezes making it less dense. This is why ice floats in water.
11. Most substances ____contract_____________when they are cooled.
12. The common temperature scale used by most Americans is the __Fahrenheit________________scale.
13. Scientists use either the ____Kelvin______________scale or the ______Celsius___________ scale.
14. Temperature __decreases_______________ as the average kinetic energy decreases.
15. T/F Thermal energy depends partly on the temperature of a substance. It also depends on mass.
16. T/F A cup of water at 283 K and a pot of water at 283 K have the same thermal energy.
17. T/F Heat is a transfer of energy between two objects with different temperatures.
18. T/F Conduction occurs in fluids.
19. T/F Convection currents result from temperature differences in liquids and gases.
20. T/F Radiation is the means by which the energy from the sun is transferred to Earth.
21. Which of the following temperatures is the lowest?
a. 100 °C
b. 100 °F
c. 100 K
d. They are the same
22. Convert the following temperatures using the formulas at the bottom of the page.
a. 70 °F = _21.1__ °C
b. 100 K = _-279.4___°F
c. 22 °C = ___295__ K
23. Compared with the Pacific Ocean, a cup of hot chocolate has
a. More thermal energy and a higher temperature
b. Less thermal energy and a higher temperature
c. More thermal energy and a lower temperature
d. Less thermal energy and a lower temperature
24. Which of the following materials would NOT be a good insulator?
a. Wood
b. Cloth
c. Metal
d. Rubber
25. The weather forecast calls for a temperature of 86 °F. What is the corresponding temperature in °C? Kelvin?
C = (86 F – 32)/1.8 = 30 deg C
K = 30 + 273 = 303 K
26. If you had your choice, would you rather sit on wooden bleachers or on metal bleachers during a football game on a freezing cold day? Explain using vocabulary from Ch. 10.
Wooden bleachers would not feel as cold b/c wood is a poor thermal conductor and would not transfer heat from my body as quickly. Metal bleachers would feel cold b/c metal is a good thermal conductor and would quickly transfer heat from my body making me feel cold. Eventually, however, my body and the bench would reach thermal equilibrium and be the same temperature.
27. Explain why the water in a swimming pool seems much colder if you jump in after being in a hot tub. Explain using vocabulary from Ch. 10.
While in the hot tub, KE from the hot tub water would transfer to my body making me feel hot. Then when I jumped into the pool the KE from my body would transfer to the pool making me feel cold. When there is a big temperature difference, the rate of heat transfer is greater than when there is a small temperature difference. (Please Pass the Heat Lab)
28. Give a real life example of each of the following types of energy transfer:
a. Conduction - answers vary
b. Radiation – answers vary
c. Convection – answers vary
Temperature Conversion Formulas:
°F = 1.8 (°C) + 32
°C = (°F – 32)/1.8
K = °C + 273
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