# A2L Item 264

Goal: Unspecified.

Source: Unspecified.

An object’s motion is described by the graph: What is the average velocity during the first 10s?

1. 0 m/s
2. 2 m/s
3. 3 m/s
4. 4 m/s
5. 5 m/s
6. Other

None provided.

# A2L Item 260

Goal: Interrelate representations of kinematical quantities

Source: CT151.2-10 An object’s motion is described by the graph above. The displacement
of the object during the entire 16 seconds is most nearly…

1. 200 meters
2. 250 meters
3. 300 meters
4. 350 meters
5. 400 meters
6. 450 meters
7. Cannot be determined

### Commentary:

(7) Students have difficulty reading graphs and finding areas.

# A2L Item 258

Goal: Hone the concept of average velocity

Source: CTtil2;12;02

While traveling from Boston to Hartford, Person A drives at a constant
speed of 55 mph for the entire trip. Person B drives at 65 mph for half
the trip and then drives 45 mph for the second half of the trip. When
would B arrive in Hartford relative to A?

1. B arrives before A.
2. B arrives at the same time as A.
3. B arrives after A.
4. Not enough information.

### Commentary:

(3) Many students are inclined to average the speeds and conclude that
they arrive at the same time. It is often useful to compare this
situation to the one in which time is halved.

# A2L Item 259

Goal: Interrelate representations of kinematical quantities

Source: CT151.2-8 An object’s motion is described by the graph above. The position of the
object at t = 9 seconds is most nearly…

1. 0 meters
2. 200 meters
3. 300 meters
4. 400 meters
5. 500 meters
6. Cannot be determined

### Commentary:

(6) This problem is primarily to determine if students appreciate the
information available from a graph. Many students will determine the
displacement forgetting that the initial position is unknown.

# A2L Item 169

Goal: Link acceleration to the slope of a velocity/time graph

Source: CT151.2-6 An
object’s motion is described by the graph above. The instantaneous
acceleration at t=10 sec is most nearly…

1. 0 m/s2
2. -2 m/s2
3. 3 m/s2
4. -4 m/s2
5. 5 m/s2
6. Other

### Commentary:

(1) Useful follow-up questions include; when does the object have
positive acceleration, when negative acceleration; does the object ever
stop?; when is it farthest from the origin?

# A2L Item 167

Goal: Problem solving

Source: UMPERG-ctqpe118 A mass
m slides down a frictionless track of radius R=0.5m. As the mass
reaches the bottom, relative to the center of curvature, its angular
velocity is most nearly:

6. Cannot be determined

### Commentary:

(1) The velocity near the bottom can be found using energy
conservation.

# A2L Item 165

Goal: Problem solving and developing strategic knowledge

Source: UMPERG-ctqpe103

You are given this problem: A
block sits on a frictionless incline. Given the angle of incline, the
distance along the incline, and that the block is initially at rest,
find the speed after traveling a distance d.

What principle would you use to solve the problem MOST EFFICIENTLY?

1. Kinematics only
2. F = ma or Newton’s laws
3. Work-Energy theorem
4. Impulse-Momentum theorem
5. Angular Impulse-Angular Momentum
6. 1 and 2
7. 1 and 3
8. 2 and 3
9. None of the above
10. Not enough information given

### Commentary:

(3) The change in gravitational potential can be found directly.
Alternately, the work done by the gravitational force must be equal to
the change in kinetic energy.

# A2L Item 161

Goal: Problem solving with kinematics

Source: CT151.2-4

Ann is running with a constant speed of 3 m/s on a straight track. Deb
is also running with constant speed but is initially 10 m behind Ann. If
Deb catches up to Ann after Deb has traveled 55 m, how fast is Deb
running?

1. 3.2 m/s
2. 3.55 m/s
3. 3.75 m/s
4. 4.15 m/s
5. More than 4.2 m/s
6. none of the above
7. cannot be determined