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Thermal Energy Study Guide
8th Grade PSI
Name: __________________________
Definitions: Define the following terms and/or concepts.
1. Temperature
2. Kinetic Energy
3. Thermal expansion
4. Thermal contraction
5. Potential Energy (between molecules)
6. Thermal Energy
7. Heat
8. Thermal Equilibrium
9. Conduction
10. Radiation
11. Convection
12. Conductors
13. Insulators
14. Specific heat
15. Thermodynamics
16. Work
17. 1st law of thermodynamics
18. 2nd law of thermodynamics
19. Entropy
20. Heat engine
Multiple Choice: Select the answer choice that best completes the statement or
answers the question.
21. When a liquid is cooled, the liquid molecules
a. spread farther apart.
b. move slower than before.
c. experience thermal contraction.
d. increase their kinetic energy.
22. This type of heat transfer can occur in outer space.
a. Conduction
b. Convection
c. Radiation
d. Entropy
23. An insulator is a material that has molecules that
a. are closely packed together.
b. move easily past one another.
c. do not transfer heat easily.
d. will shrink when heated.
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8th Grade PSI
Thermal Energy
24. The following objects are all heated from 10°C to 30°C. Which object will transfer
the most energy to your hand?
a. 5kg apples
b. 2kg apples
c. 5kg gold
d. 2kg gold
25. Two objects of the same material but different masses are subjected to the same
thermal energy input.
a. The object with less mass will experience a greater change in temperature.
b. The object with more mass will experience a greater change in temperature.
c. They will both experience the same change in temperature.
d. It is impossible to compare their changes in temperature without knowing the
specific heats of the objects.
26. All of the following are examples of conductors except ___.
a. silver
b. water
c. air
d. aluminum
27. A 80°C object and a 60°C object sit (not touching) in a 21°C environment. Which
best explains what will happen?
a. Both objects will get warmer.
b. The warmer object will exchange heat with the environment at a slower rate.
c. The environment will get warmer.
d. The warmer object will cool down while the cooler object will stay the same
temperature.
28. Which is an example of heat transfer by convection?
a. Touching a hot pan and burning your finger
b. Water boiling in a pot on the stove
c. Feeling the warmth of a campfire on your face
d. The sun warming the roof of a house
29. Which of the following is an example of energy conservation?
a. An apple hangs suspended from a tree.
b. A person stands on tiptoes.
c. A car waits at a red light.
d. A hockey puck slides to a stop due to friction.
30. When energy is transferred as heat, the amount of useable energy ___.
a. decreases
b. remains the same
c. increases
d. is always zero
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8th Grade PSI
Thermal Energy
Short Response: Answer the following thoroughly. A table of specific heats is
attached for reference.
Substance
Aluminum
Apples
Bricks
Carbon
Copper
Gold
Iron
Mercury
Steam
Tin
Water
Wood
Specific Heat
(J/kg °C)
897
3,300
800
709
385
129
449
140
1,870
230
4,186
1,700
31. How are temperature and kinetic energy related?
32. Describe what happens to motion and spacing of molecules when heated or
cooled for a:
a. liquid
b. solid
c. gas
33. What does a thermometer measure?
34. Describe characteristics of the three temperature scales including freezing and
boiling point of water for each.
35. Complete the following conversions:
a. 37°C to Fahrenheit
b. 384 Kelvin to degrees Celsius
c. -45°C to Kelvin
d. 45 °F to degrees Celsius
36. Using the ideas of thermal expansion and contraction, describe how a liquid
thermometer works.
37. Recall the video shown in class of the bimetallic strip that was bent when it was
heated. Explain why it bent. (HINT: Remember that the strip was made of two
different metals.)
38. When does potential energy between molecules increase? Decrease?
39. What two types of energy do molecules possess?
40. Explain why thermal energy and temperature, though related, are different.
41. Provide an example of when two substances might have the same temperature
but different thermal energy.
42. How are heat flow and temperature differences related?
43. Which will cool fastest initially in a room temperature room? Boiling water or
lukewarm water?
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8th Grade PSI
Thermal Energy
44. Will heat flow between two objects touching that have the same temperature?
Why or why not?
45. Which direction does heat flow? Give an example.
46. What are the three methods of thermal energy transfer? Give two examples of
each.
47. Do all objects emit the same amount of radiation? Why or why not?
48. Conduction occurs primarily in solids. Why?
49. What is the primary difference between conductors and insulators?
50. Give several examples of conductors and insulators.
51. If you wanted water to boil quickly in a tea kettle, what kind of material would you
use for the tea kettle?
52. If you wanted to maximize heat transfer, what kind of material would you use?
How about if you wanted to minimize heat transfer?
53. If you have several spoons made of conducting materials and insulating
materials, which will feel cooler to the touch and why?
54. Suppose you took a bite of pie that was at a certain temperature. The crust
doesn’t burn you but the filling does. Using the idea of specific heat, explain why
the filling burned you but the crust didn’t even though they had the same
temperature.
55. State whether the variable is “inversely” or “directly” proportional to the
temperature change. Provide an illustrative example for each.
a. mass
b. specific heat
c. thermal energy transferred
56. Calculate the heat input (or output) required to change the temperature of 3kg of
iron by 3 degrees Celsius.
57. Calculate the final temperature of 0.020 kg of mercury that loses 500J of
thermal energy and started with a temperature of 400Kelvin.
58. Calculate the change in temperature of 10kg of wood that gains 3,000J of
thermal energy.
59. Give an example of the 1st law of thermodynamics in action.
60. What energy conversions are involved in a heat engine?
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8th Grade PSI
Thermal Energy