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8th Grade
Thermal Energy Study Guide
2015-10-09
www.njctl.org
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Part 1
Thermal Energy
Define the following terms and/or concepts
Study Guide
www.njctl.org
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1
Temperature
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2
Kinetic Energy
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3
Thermal expansion
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4
Thermal contraction
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5
Potential Energy (between molecules)
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6
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7
Heat
Thermal Energy
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8
Thermal Equilibrium
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9
Conduction
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10
Radiation
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11
Convection
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12
Conductors
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13
Insulators
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14
Specific heat
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15
Thermodynamics
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16 Work
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17
1st law of thermodynamics
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18
2nd law of thermodynamics
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19
entropy
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20 heat engine
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21 When a liquid is cooled, the liquid molecules
A spread farther apart.
Part 2
Directions: Select the answer choice that best
completes the statement or answers the question.
B move slower than before.
C experience thermal contraction.
D increase their kinetic energy.
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22 This type of heat transfer can occur in outer
space.
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23 An insulator is a material that has molecules that
A are closely packed together.
A Conduction
B move easily past one another.
B Convection
C do not transfer heat easily.
C Radiation
D will shrink when heated.
D Entropy
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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
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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 heat of
the objects.
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26 All of the following are examples of conductors
except
A Silver
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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 Water
C Air
B The warmer object will exchange heat with the
environment at a slower rate.
D Aluminum
C The environment will get warmer.
D The warmer object will cool down while the cooler
object will stay the same temperature.
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28 An example of heat transfer by convection is
A touching a hot pan and burning your finger
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29 Which of the following is an example of energy
conservation?
A An apple hangs suspended from a tree.
B water boiling in a pot on the stove
B A person stands on tiptoes.
C feeling the warmth of a campfire on your face
C A car waits at a red light.
D the sun warming the roof of a house
D A hockey puck slides to a stop due to friction.
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30 When energy is transferred as heat, the amount
of useable energy
A decreases.
B remains the same.
C increases.
D is always zero.
Part 3
Directions: Answer the following thoroughly. A
table of specific heats is attached.
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Substance
Aluminum
Specific Heat (J/kg °C)
3,300
Bricks
800
Carbon
709
Copper
385
Gold
129
Iron
449
Mercury
140
Tin
31 How are temperature and kinetic energy related?
897
Apples
Steam
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1,870
230
Water
4,186
Wood
1,700
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32 Describe what happens to motion and spacing of
molecules when heated or cooled for a:
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33 What does a thermometer measure?
A liquid
B solid
C gas
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34 Describe characteristics of the three temperature
scales including freezing and boiling point of
water for each.
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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
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36 Using the ideas of thermal expansion and
contraction, describe how a liquid thermometer
works.
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38 When does potential energy between molecules
increase? Decrease?
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40 Explain why thermal energy and temperature,
though related, are different.
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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)
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39 What two types of energy do molecules possess?
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41 Provide an example of when two substances
might have the same temperature but different
thermal energy.
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42 Which will cool fastest initially in a room
temperature room? Boiling water or lukewarm
water?
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44 Will heat flow between two objects touching that
have the same temperature? Why or why not?
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46 What are the three methods of thermal energy
transfer? Give a couple of examples of each.
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43 How are heat flow and temperature differences
related?
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45 Which direction does heat flow? Give an example.
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47 Do all objects emit the same amount of radiation?
Why or why not?
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48 Conduction occurs primarily in solids. Why?
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50 Give several examples of conductors and
insulators.
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52 If you wanted to maximize heat transfer, what
kind of material would you use? How about if you
wanted to minimize heat transfer?
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49 What is the primary difference between
conductors and insulators?
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51 If you wanted water to boil quickly in a tea kettle,
what kind of material would you use for the tea
kettle?
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53 If you have several spoons made of conducting
materials and insulating materials, which will feel
cooler to the touch and why?
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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.
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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
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56 Calculate the heat input (or output) required to
change the temperature of 3kg of iron by 3
degrees Celsius.
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58 Calculate the change in temperature of 10kg of
wood that gains 3,000J of thermal energy.
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57 Calculate the final temperature of 0.020 kg of
mercury that loses 500J of thermal energy and
started with a temperature of 400Kelvin.
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59 Give an example of the 1st law of
thermodynamics in action.
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60 What energy conversions are involved in a heat
engine?