Clicker Questions for NEXUS/Physics
Thermodynamics
A note on usage:
The clicker slides in this booklet are meant
to be used as stimuli to encourage class discussion.
They are intended for use in a class that attempts
to help students develop a coherent and sophisticated
understanding of scientific thinking.
They are NOT intended as items to test whether
students are “right or wrong” or “know” the correct
answer by one-step recall if enough cues are given.
This has a number of instructional implications
that are reviewed in general on the next four slides.
The individual slides also contain annotations
discussing their intended use.
Usage: 1
• Feedback
One of the most important values of a clickerresponse system is to provide instructors with
some understanding of what students are thinking.
Good clicker questions can be highly revealing
(and surprising). But the critical fact is not that the
students make mistakes but to use those mistakes
to probe their thinking and find out why.
This raises the importance of a rich subsequent
discussion well above “letting the students know
what the right answer is.”
Usage 2:
• Student-student interactions
The critical value for student learning occurs
in what happens after a clicker question has
obtained a mixed response from the students.
The standard next cue is, “Find someone
who disagreed with the answer you chose
and see if you can convince them.”
After a minute or two of discussion, a second click
may show students having moved dramatically
towards the correct answer. A brief call for who
changed their answer and why can lead to a
useful exchange. When they have not moved
significantly, more discussion is called for.
Usage: 3
• Incompletely specified questions
Some items have questions that are simple if idealized
assumptions are made, subtler if they are not. Part of
the discussion of these items are intended to include
issues of modeling, idealizations, and hidden
assumptions.
• Questions where answers are not provided.
In these items, the intent is to have students come up
with potential answers and have the instructor collect
them and write them on the board.
Occasionally, especially at the beginning of a class, it may
take some time before students are willing to contribute
answers. It can help if you have some prepared answers
ready, walk around the class, and put up the answers as if
they came from the students. This can help students get
more comfortable with contributing.
Usage: 4
• Cluster questions
Some questions are meant to be used as part of a
group of questions. In this case, resolving the answers
to individual questions is better left until the entire
group is completed. The value of the questions are
often in the comparison of the different items and in
having students think about what changes lead to what
differences and why.
• Problem solving items
In these items (indicated by a pencil cluster logo), the
intent is to have students work together to solve some
small problem. After a few minutes, ask the groups to
share their answers, vote on the different answers
obtained, and have a discussion.
Critical Experiment 1
If we have equal
amounts of the same
kinds of materials at
different temperatures
and put them together,
what happens?
A.
B.
C.
D.
E.
pretty close to 50 C
pretty close to 80 C
pretty close to 20 C
greater than 80 C
less than 20 C
200 g of
water
at 80 °C
200 g of
water
at 20 °C
Critical Experiment 2
If we have unequal
amounts of the same
kinds of materials at
different temperatures
and put them together,
what happens?
A.
B.
C.
D.
E.
pretty close to 40 C
pretty close to 80 C
pretty close to 20 C
greater than 60 C
something else
100 g of
water
at 80 °C
200 g of
water
at 20 °C
Critical Experiment 3
If we have equal
masses of different kinds
of materials at different
temperatures and put
them together, what
happens?
A.
B.
C.
D.
E.
pretty close to 50 C
pretty close to 80 C
pretty close to 20 C
greater than 80 C
less than 20 C
200 g of
copper
at 80 °C
200 g of
water
at 20 °C
The objects listed in A-C below are
placed in an oven heated to 90 C
(~160 F) and left for a long time.
Which object will feel warmest
when you touch it?
A.
B.
C.
D.
A ball of cotton
A stick of wood
A metal bar
They would all feel
the same
The objects listed in A-C below are
placed in an oven heated to 90 C
(~160 F) and left for a long time.
Which object will have the highest
temperature?
A.
B.
C.
D.
A ball of cotton
A stick of wood
A metal bar
They would be
the same temperature
When baking a potato (white or sweet) in the oven,
I find they come out much more uniformly cooked
if I stick aluminum rods into the potato. (You can buy
such rods in any kitchen supply store.)Why do you think
this works?
A. Because the aluminum has a much higher specific heat
than the potato and so it holds a lot of thermal energy.
B. Because the aluminum has a much lower specific heat
than the potato and so it lets the potato have most of the
thermal energy.
C. Because the aluminum has a much higher thermal
conductivity than the potato so putting the rods in brings
the thermal energy into the center of the potato more
quickly so it cooks more uniformly.
D. Some other reason.
When I bake a sweet potato in the oven, I always put it
on a thin sheet of aluminum foil. This is because
sometimes the potato exudes a sugary juice that burns
and makes a hard-to-clean-up mess if it drips on the
bottom of the oven. When I’m ready to take the potato
out of the hot (400o F) oven after an hour of cooking, I
find I can pick up the aluminum foil with my bare hands
without getting burned. Why do you think this is so?
A. Because the aluminum foil has a high specific heat so
that it holds on to most of the thermal energy.
B. Because the aluminum foil has a low specific heat and
not much mass, so even at a high temperature it
doesn’t have a lot of thermal energy in it to burn me.
C. Because the aluminum foil has a low thermal
conductivity so that although the foil is hot, the heat
doesn’t flow into my hand.
D. Because the aluminum foil doesn’t
get hot in the oven, even though
the oven is at a high temperature.
E. Some other reason.
A block sitting on a smooth table was given a
push. It slides across the table and comes to a
stop. After the push is complete but before the
block has stopped, which of the following
statements are (pretty close to being) true?
A. The mechanical energy of the block is conserved.
B. The mechanical plus thermal energy of the block is
conserved.
C. The mechanical energy of the block plus table is
conserved.
D. The mechanical plus thermal energy of the block
plus table is conserved.
E. Mechanical + thermal energy is not conserved
in this process.
Suppose an isolated box of volume 2V is divided
into two equal compartments. An ideal gas occupies
half of the container and the other half is empty.
When the partition separating the two halves of the box
is removed and the system reaches equilibrium again,
how does the new internal energy of the gas compare
to the internal energy of the original system?
A.
B.
C.
D.
The internal energy increases
The internal energy decreases
The internal energy stays the same
There is not enough information to
determine the answer
What are the signs of the following first
law quantities for: an egg placed in
boiling water
1
2
3
4
5
6
7
8
9
ΔUinternal
Q (heat absorbed
W (work done BY the
BY the system)
system)
>0
0
<0
<0
0
>0
0
>0
>0
>0
>0
0
<0
>0
>0
0
<0
>0
>0
<0
<0
<0
<0
0
0
0
0
What are the signs of the following first
law quantities for: a person standing
still holding an object at arm’s length
1
2
3
4
5
6
7
8
9
ΔUinternal
Q (heat absorbed
W (work done BY the
BY the system)
system)
>0
0
<0
<0
0
>0
0
>0
>0
>0
>0
0
<0
>0
>0
0
<0
>0
>0
<0
<0
<0
<0
0
0
0
0
What are the signs of the following first
law quantities for: a flashlight left on
1
2
3
4
5
6
7
8
9
ΔUinternal
Q (heat absorbed
W (work done BY the
BY the system)
system)
>0
0
<0
<0
0
>0
0
>0
>0
>0
>0
0
<0
>0
>0
0
<0
>0
>0
<0
<0
<0
<0
0
0
0
0
A gas is held behind a partition in an insulated chamber,
the other side of the partition is vacuum. The partition
breaks involving negligible energy change.
What happened after equilibrium is reached?
1
2
3
4
5
6
7
8
9
ΔUinternal
Q (heat absorbed
W (work done BY the
BY the system)
system)
>0
0
<0
<0
0
>0
0
>0
>0
>0
>0
0
<0
>0
>0
0
<0
>0
>0
<0
<0
<0
<0
0
0
0
0
During soccer practice one of your teammates sprains her ankle.
You take an “instant cold pack” from the first aid box to use on
her ankle. It is not at all cold when you take it out. The instructions
on the cold pack tell you to punch the pack so that you break open
a sack of chemicals inside it. When you do that you notice that the
cold pack rapidly becomes quite cold. What happened?
A. By punching the pack you gave the chemicals inside
the energy they needed to permit the cooling down.
B. A chemical reaction produced cold as one of its
products, which cooled down the cold pack.
C. The cold pack forcefully expelled heat into its
surroundings, which lowered its temperature.
D. Thermal energy was used up in forming chemical
bonds, which made the cold pack colder.
E. More than one of these
F. None of these
After a long time passes, the cold pack
returns to room temperature. Why?
A. The chemical reaction that made it colder runs
in the reverse direction, making it warmer.
B. Heat is transferred from your teammate’s ankle to
the cold pack, making her ankle colder and the cold
pack warmer.
C. Cold is transferred from the cold pack to your
teammate’s ankle, making her ankle colder and the
cold pack warmer.
D. Chemical bonds are formed, releasing energy and
heating up the cold pack.
E. More than one of these
F. None of these
After the cold pack returns to room temperature,
what can you say about
the total energy (chemical, thermal,
and anything else) stored in the cold pack?
A. It is greater than when you first took the cold
pack out of the first-aid kit.
B. It is less than when you first took the cold pack
out of the first-aid kit.
C. It is equal to when you first took the cold pack
out of the first-aid kit.
D. Not enough information to tell.