Clicker Questions for NEXUS/Physics
Work and Energy
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.
Both balls are launched at the same speed.
Which one gets to the end first?
1. The one on the straight track.
2. The one on the dipped track.
3. They are the same.
Each row in the following table pairs a force
vector with a corresponding displacement
resulting in work W being done.
In which of these rows
F
is the work done zero?
A.
.
B.
.
C.
.
D.
.
E.
.
F.
None.
Dr
Each row in the following table pairs a force
vector with a corresponding displacement
resulting in work W being done.
In which of these rows
F
is the work done positive?
A.
.
B.
.
C.
.
D.
.
E.
.
F.
None.
Dr
A young girl wants to select one of the
(frictionless) playground slides illustrated below
to give her the greatest possible speed when she
reaches the bottom of the slide.
Which should she choose?
5. It doesn’t matter. It would be the same for each.
A young girl wants to select one of the
(frictionless) playground slides illustrated below
to reach the ground in the shortest possible time.
Which should she choose?
5. It doesn’t matter. It would be the same for each.
Two identical carts A and B roll down a hill and collide as
shown in the figures at the right.
(i): A starts from rest. It rolls down and collides head-on
with B which is initially at rest on the ground. The two carts
stick together.
(ii): A and B are at rest on opposite. They roll
down, collide head-on and stick together.
Which statement is true about the two-cart
system just before the carts collide
in the two cases?
1.
2.
3.
4.
5.
The kinetic energy of the system is zero
in case (ii).
The kinetic energy of the system
is greater in case (i) than in case (ii).
The kinetic energy of the system
is greater in case (ii) than in case ii).
The kinetic energy of the system is
the same in both cases (but not 0).
More than one statement is true.
Two identical carts A and B roll down a hill and collide as
shown in the figures at the right.
(i): A starts from rest. It rolls down and collides head-on
with B which is initially at rest on the ground. The two carts
stick together.
(ii): A and B are at rest on opposite. They roll
down, collide head-on and stick together.
Which statement is true about the two-cart
system just after the carts collide and stick
in the two cases?
1.
2.
3.
4.
5.
The kinetic energy of the system is zero
in case (ii).
The kinetic energy of the system
is greater in case (i) than in case (ii).
The kinetic energy of the system
is greater in case (ii) than in case ii).
The kinetic energy of the system is
the same in both cases (but not 0).
More than one statement is true.
Two identical carts A and B roll down a hill and collide as
shown in the figures at the right.
(i): A starts from rest. It rolls down and collides head-on
with B which is initially at rest on the ground. The two carts
stick together.
(ii): A and B are at rest on opposite. They roll
down, collide head-on and stick together.
Which statement is true about the two-cart
system just before the carts collide
in the two cases?
1.
2.
3.
4.
5.
The momentum of the system is zero
in case (ii).
The momentum of the system
is greater in case (i) than in case (ii).
The momentum of the system
is greater in case (ii) than in case ii).
The momentum of the system is
the same in both cases (but not 0).
More than one statement is true.
Two identical carts A and B roll down a hill and collide as
shown in the figures at the right.
(i): A starts from rest. It rolls down and collides head-on
with B which is initially at rest on the ground. The two carts
stick together.
(ii): A and B are at rest on opposite. They roll
down, collide head-on and stick together.
Which statement is true about the two-cart
system just after the carts collide and stick
in the two cases?
1.
2.
3.
4.
5.
The momentum of the system is zero
in case (ii).
The momentum of the system
is greater in case (i) than in case (ii).
The momentum of the system
is greater in case (ii) than in case ii).
The momentum of the system is
the same in both cases (but not 0).
More than one statement is true.
A spring-loaded toy dart gun is used to shoot a dart
straight up in the air, and the dart reaches a maximum
height of 24 m. The same dart is shot straight up a
second time from the same gun, but this time the spring
is compressed only half as far before firing. How far up
does the dart go this time, neglecting friction and air
resistance and assuming an ideal spring?
1.
2.
3.
4.
5.
6.
7.
96 m
48 m
24 m
12 m
6m
3m
Something else
The diagram depicts two pucks on a
frictionless table. Puck II is four times
as massive as puck I. Starting from
rest, the pucks are pushed across the
table by two equal forces.
Which puck will have the greater KE
upon reaching the finish line?
A. Puck I
B. Puck II
C. Both will have the same.
D. There is not enough information to
decide.
The diagram depicts two pucks on a
frictionless table. Puck II is four times
as massive as puck I. Starting from
rest, the pucks are pushed across the
table by two equal forces.
Which puck reach the finish line first?
A. Puck I
B. Puck II
C. Both will have the same.
D. There is not enough information to
decide.
The diagram depicts two pucks on a
frictionless table. Puck II is four times
as massive as puck I. Starting from
rest, the pucks are pushed across the
table by two equal forces.
Which puck will have the greater
momentum upon reaching the finish line?
A. Puck I
B. Puck II
C. Both will have the same.
D. There is not enough information to
decide.
A bulldog on a skateboard is moving very slowly
when he encounters a 2 m dip. How fast will he be going
when he is at the bottom of the dip? The bulldog and
skateboard combined have a mass of 20 kg.
Friction and air drag can be ignored.
1. Very slowly
2. About 2 m/s
3. About 6 m/s
4. You can’t tell from the
information given.
A bulldog on a skateboard is moving very slowly
when he encounters a 2 m dip.
The bulldog and skateboard combined have a mass of 20 kg.
What is their total mechanical energy?
1. Almost zero
2. About 200 Joules
3. About 600 Joules
4. You can’t tell from the
information given.
A bulldog on a skateboard is moving very slowly
when he encounters a 2 m dip. How fast will be be going
when he is at the bottom of the dip? The bulldog and
skateboard combined have a mass of 20 kg.
Friction and air drag can be ignored.
1. Very slowly
2. About 2 m/s
3. About 6 m/s
4. You can’t tell from the
information given.
A bulldog on a skateboard is moving very slowly
when he encounters a 2 m dip. The bulldog and skateboard
combined have a mass of 20 kg.
What is their total mechanical energy?
1. Almost zero
2. About 200 Joules
3. About 600 Joules
4. You can’t tell from the
information given.
A bulldog on a skateboard is sitting at the bottom
of a 2 m dip. How much KE do you have to give them so
they will roll out of the dip? The bulldog and skateboard
combined have a mass of 20 kg.
Friction and air drag can be ignored.
1. None
2. About 400 Joules
3. About 600 Joules
4. You can’t tell from the
information given.
A bulldog on a skateboard is sitting at the bottom
of a 2 m dip. How much KE do you have to give them so
they will roll out of the dip? The bulldog and skateboard
combined have a mass of 20 kg.
Friction and air drag can be ignored.
1. None
2. About 400 Joules
3. About 600 Joules
4. You can’t tell from the
information given.
Two carts on an air track are pushed towards
each other. Initially, cart 1 moves in the +x direction
and cart 2 moves in the -x direction. They bounce off
each other elastically. Identify which graph is a
possible display of the momentum of cart 1
as a function of time.
Two carts on an air track are pushed towards
each other. Initially, cart 1 moves in the +x direction
and cart 2 moves in the -x direction. They bounce off
each other elastically. Identify which graph is a
possible display of the force on cart 2
as a function of time.
Two carts on an air track are pushed towards
each other. Initially, cart 1 moves in the +x direction
and cart 2 moves in the -x direction. They bounce off
each other elastically. Identify which graph is a
possible display of the position of cart 1
as a function of time.
Two carts on an air track are pushed towards
each other. Initially, cart 1 moves in the +x direction
and cart 2 moves in the -x direction. They bounce off
each other elastically. Identify which graph is a
possible display of the position of cart 2
as a function of time.
Is it possible for a system of interacting
objects to conserve momentum but not
mechanical energy (kinetic + potential)?
A. Yes
B. No
Is either momentum, mechanical energy,
or both conserved for the following system?
–- A ball thrown straight upward.
A.
B.
C.
D.
Momentum only
Mechanical energy only
Both momentum & ME
Neither
Is either momentum, mechanical energy,
or both conserved for the following system?
–- a block sliding on a smooth table after
being pushed but before it comes to a stop.
(Smooth ≠ frictionless!).
A.
B.
C.
D.
Momentum only
Mechanical energy only
Both momentum & ME
Neither
Is either momentum, mechanical energy,
or both conserved for the following system?
–- a heavy cylinder (A) with frictionless
wheels rolling along on a horizontal table
top and a lighter cylinder (B) that is lightly
dropped onto the moving cylinder
A.
B.
C.
D.
Momentum only
Mechanical energy only
Both momentum & ME
Neither
Is either momentum, mechanical energy,
or both conserved for the following system?
–- an cart on an inclined air track with a
spring on the bottom. The cart slides up
and down the incline, bouncing off the
spring when it hits the bottom.
A.
B.
C.
D.
Momentum only
Mechanical energy only
Both momentum & ME
Neither
What does the electric potential
energy between two identical charges
look like?
What does the electric potential
energy between two opposite charges
look like?
Two test charges are brought separately into
the vicinity of a charge +Q. First, test charge
+q is brought to point A a distance r from +Q.
Next, +q is removed and a test charge +2q is
brought to point B a distance 2r from +Q.
Compared with the
electrostatic potential energy
of pair of charges in case A,
the PE in case B is
1. greater
2. smaller
3. the same
4. you can’t tell from
the information given
When a positive (test) charge is released
from rest near a fixed positive (source) charge
what happens to the electric potential energy
of the test charge?
A.
It will increase because the test charge will move
towards the source charge.
B.
It will decrease because the test charge will move
away from the source charge.
C.
It will increase because the test charge will move
away from the source charge.
D.
It will decrease because the test charge will move
towards the source charge.
E.
It will remain constant because the test charge remains at rest.
F.
There is not enough information to tell.
When a negative (test) charge is released
from rest near a fixed positive (source) charge
what happens to the electric potential energy
of the test charge?
A.
It will increase because the test charge will move
towards the source charge.
B.
It will decrease because the test charge will move
away from the source charge.
C.
It will increase because the test charge will move
away from the source charge.
D.
It will decrease because the test charge will move
towards the source charge.
E.
It will remain constant because the test charge remains at rest.
F.
There is not enough information to tell.
Which of these configurations
has the largest electric PE?
A.
B.
C.
D.
E.
F.
G.
A
B
C
D
A and C
B and D
other
Topo map = grav PE graph
(2D)
At which point is
the force downhill
the strongest?
A. A
B. B
C. C
Topo map = grav PE graph
(2D)
At which point is
the force downhill
pointing east?
(North is up)
A.
B.
C.
D.
A
B
C
None
Topo map = grav PE graph
(2D)
At which point is
the force downhill
pointing north?
(North is up)
A.
B.
C.
D.
A
B
C
None
Model of PE for
2
line charges
(3D)
Model of PE for 2 line charges
Where would
a test charge feel
the strongest
electric force?
A. A
B. B
C. C
D. A and C
Model of PE for 2 line charges
Where would
a test charge feel
the strongest
electric force?
A.
B.
C.
D.
E.
A
B
C
A and C
It would feel
no force at any
of the three points
Map of electric PE
for 3 charges (water molecule) (3D)
Where would a test charge
feel the strongest electric
force?
A. A
B. B
C. C
D. D
E. E
F. More than one