Free Practice Quiz Question List

4 Momentum and Collisions Online Quiz Questions

Use this free practice quiz with 20 questions to review 4 Momentum and Collisions, test your knowledge, and prepare for your next test or exam.

20 questions

Choose one

1 point

A $1.2\,\text{kg}$ cart moving at $+4.0\,\text{m/s}$ collides with a $0.8\,\text{kg}$ cart moving at $-1.0\,\text{m/s}$ . They stick together, and external impulse is negligible. What is their shared final velocity?

A
+2.0 m/s
B
+1.0 m/s
C
−2.0 m/s
D
+4.0 m/s

Choose one

1 point

A system contains two objects during a collision. Under which condition can you conclude that the system's total momentum is conserved during the collision?

A
Whenever the objects exert forces on each other
B
When the system's net external impulse is zero or negligible
C
Only when the collision is elastic
D
Only when the objects stick together

Choose one

1 point

Two equal-mass objects collide elastically in one dimension. One is initially at rest. What happens to their velocities after the collision?

A
The objects exchange velocities.
B
Both objects must come to rest.
C
The moving object keeps its velocity and the resting object remains at rest.
D
The objects must stick together.

Choose all

1 point

A two-object system collides, and the net external impulse during the collision is negligible. Select all statements that correctly describe the forces or momentum of this system.

A
Forces between the two objects are internal to the two-object system.
B
The internal forces during the collision occur in equal-and-opposite pairs.
C
A zero net external impulse allows the system's total momentum to remain constant.
D
The internal forces guarantee that each object's momentum remains unchanged.

Choose all

1 point

A protective surface increases the time over which an object slows down. Select all statements that correctly describe impulse and the average force when the object's momentum change is fixed.

A
Impulse equals the change in momentum.
B
For a fixed momentum change, a longer stopping time means a smaller average force magnitude.
C
A longer contact time always means a larger impulse, regardless of the momentum change.
D
Impulse and momentum have different SI units.

True or false

1 point

If a system's net external impulse is negligible during a collision, its total momentum is conserved whether the collision is elastic or inelastic.

A
True
B
False

True or false

1 point

Immediately after a perfectly inelastic collision, the colliding objects have the same velocity.

A
True
B
False

Written response

1 point

An object has initial momentum $+3.0\,\text{N·s}$ and receives an impulse of $-7.0\,\text{N·s}$ . What is its signed final momentum?

Written response

1 point

What is the kinetic energy of a $2.0\,\text{kg}$ object moving at $3.0\,\text{m/s}$ ?

Fill in the blank

1 point

A one-dimensional collision is described using a chosen positive direction. If the object's momentum change is negative, the momentum-change vector points to that positive direction.

Fill in the blank

1 point

For two objects that stick together after a one-dimensional collision, the condition on their final velocities is .

Open ended

1 point

A system consists of two objects moving along one axis. Object 1 has mass $1.5\,\text{kg}$ and velocity $+2.0\,\text{m/s}$ ; object 2 has mass $0.5\,\text{kg}$ and velocity $-2.0\,\text{m/s}$ . During the interval, the system receives an external impulse of $-3.0\,\text{N·s}$ . This external impulse is not negligible. Find the system's final total momentum and explain whether you can use conservation of momentum for this interval.

Written response

1 point

A $0.30\,\text{kg}$ object moves at $+2.0\,\text{m/s}$ along the chosen positive axis. What is its signed momentum component along that axis?

True or false

1 point

In a one-dimensional coordinate system, a negative change in an object's momentum points in the negative direction, regardless of the object's initial velocity.

A
True
B
False

Choose one

1 point

A car's airbag increases the time over which a passenger slows down. If the passenger's momentum change is the same, what effect does the longer stopping time have?

A
The average force on the person is reduced.
B
The person's momentum change becomes zero.
C
The person's mass decreases during the collision.
D
The force acts for less time.

Written response

1 point

An object of mass $1.5\,\text{kg}$ moves at $-4\,\text{m/s}$ . What is its momentum?

Choose one

1 point

An isolated collision conserves momentum, but the objects' total kinetic energy is smaller after the collision and the objects separate. How is the collision classified?

A
Elastic
B
Inelastic, but not perfectly inelastic
C
Perfectly inelastic
D
It cannot be classified unless the objects have equal masses.

Choose one

1 point

During a collision, two objects exert large forces on each other. Why do these forces not change the total momentum of the two-object system?

A
They are internal forces that occur in equal-and-opposite pairs.
B
They are external forces that cancel the system's initial momentum.
C
They increase the system's total momentum because they are large.
D
They prevent momentum from being conserved in any collision.

Choose one

1 point

Two equal-mass objects undergo a one-dimensional head-on elastic collision. One initially moves at $+6\,\text{m/s}$ , and the other is at rest. What are their velocities after the collision?

A
Both objects move at half the initial speed in the original direction.
B
The initially moving object keeps its velocity, and the other remains at rest.
C
The initially moving object stops, and the initially resting object moves at the original speed.
D
Both objects stop.

Choose one

1 point

What condition allows the total momentum of a system to remain constant during a collision?

A
The net external force is nonzero at every instant.
B
The system's net external impulse is zero or negligible during the interval.
C
The objects have equal masses.
D
The collision is perfectly inelastic.