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AP Physics 1: Algebra-Based Practice Quiz: Linear Momentum

Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026

Test your understanding with short quizzes. This quiz has 12 questions to check your progress.

Question 1 of 12

Which of the following equations correctly defines the linear momentum, $\vec{p}$, of an object with mass $m$ and velocity $\vec{v}$?

All Questions (12)

Which of the following equations correctly defines the linear momentum, $\vec{p}$, of an object with mass $m$ and velocity $\vec{v}$?

A) $\vec{p} = m\vec{v}$

B) $\vec{p} = m/\vec{v}$

C) $\vec{p} = \vec{v}/m$

D) $\vec{p} = m\vec{a}$

Correct Answer: A

The provided content explicitly defines linear momentum with the equation $\vec{p} = m\vec{v}$.

What is the relationship between the direction of an object's linear momentum and the direction of its velocity?

A) They are in opposite directions.

B) They are perpendicular to each other.

C) They are in the same direction.

D) There is no defined relationship between their directions.

Correct Answer: C

The provided content states that momentum is a vector quantity and has the same direction as the velocity.

Based on the provided information, linear momentum is best described as which type of quantity?

A) A scalar quantity

B) A vector quantity

C) A fundamental constant

D) A unitless measure

Correct Answer: B

The content specifies that 'Momentum is a vector quantity', indicating it has both magnitude and direction.

The concept of linear momentum is specified as being particularly useful for the analysis of which two types of interactions?

A) Objects at rest and objects in free fall

B) Collisions and explosions

C) Uniform circular motion and projectile motion

D) Gravitational and electromagnetic interactions

Correct Answer: B

The content explicitly states that 'Momentum can be used to analyze collisions and explosions.'

An interaction is modeled as a collision. According to the provided definition, what must be true about the forces involved in this interaction?

A) The net external force on the system must be zero.

B) The forces exerted between the objects are much larger than the net external force.

C) Only internal forces exist, and all external forces are absent.

D) The internal forces are equal in magnitude to the net external force.

Correct Answer: B

The definition of a collision model states that 'the forces exerted between the involved objects in the system are much larger than the net external force exerted on those objects during the interaction.'

A firecracker, initially at rest, bursts into several pieces that fly outward. This event is best modeled as an explosion because:

A) The total momentum of the system changes.

B) The forces involved are much larger than any external forces.

C) Forces internal to the system move objects within that system apart.

D) The interaction happens over a very short time interval.

Correct Answer: C

The provided content defines an explosion as a model for an interaction 'in which forces internal to the system move objects within that system apart.'

An object of mass $m$ has a linear momentum $\vec{p}$. If the mass of the object is doubled to $2m$ while its velocity remains constant, what is the new linear momentum?

A) $\vec{p}/2$

B) $\vec{p}$

C) $2\vec{p}$

D) $4\vec{p}$

Correct Answer: C

According to the equation $\vec{p} = m\vec{v}$, momentum is directly proportional to mass. If the mass is doubled and velocity is constant, the new momentum will be $(2m)\vec{v} = 2(m\vec{v}) = 2\vec{p}$.

Two cars crash at an intersection. For the brief moment of the crash, the forces the cars exert on each other are immense. An analyst uses a collision model and ignores the force of friction from the road during the impact. Why is this a valid approach based on the provided text?

A) Because friction is an internal force to the two-car system.

B) Because the collision model requires all external forces to be zero.

C) Because in a collision model, the internal interaction forces are assumed to be much larger than external forces like friction.

D) Because the cars moving apart after the crash is modeled as an explosion, not a collision.

Correct Answer: C

The definition of a collision model justifies this approach. It states that the internal forces (cars on each other) are 'much larger than the net external force' (like friction), allowing the external forces to be neglected for the analysis of the interaction itself.

The linear momentum of an object or system is the product of its mass and which other quantity?

A) Acceleration

B) Displacement

C) Velocity

D) Force

Correct Answer: C

The definitional equation $\vec{p} = m\vec{v}$ shows that linear momentum is the product of mass ($m$) and velocity ($\vec{v}$).

A key difference between the provided models for collisions and explosions is that:

A) Collisions involve external forces while explosions involve internal forces.

B) Explosions describe objects moving apart due to internal forces, while collisions describe interactions with large internal forces.

C) Momentum is only useful for analyzing explosions, not collisions.

D) Collisions must involve two objects, while explosions must involve more than two.

Correct Answer: B

The content defines an explosion by the outcome of objects moving apart due to internal forces. It defines a collision by the relative magnitude of internal forces compared to external forces. This represents the core distinction given in the text.

Object A has a mass of 4 kg and a velocity of 6 m/s to the east. Object B has a mass of 8 kg and a velocity of 3 m/s to the east. How do their linear momenta compare?

A) The momentum of A is greater than the momentum of B.

B) The momentum of B is greater than the momentum of A.

C) Their momenta are equal.

D) Their momenta are in opposite directions.

Correct Answer: C

Using the equation $\vec{p} = m\vec{v}$: Momentum of A is (4 kg)(6 m/s) = 24 kg·m/s east. Momentum of B is (8 kg)(3 m/s) = 24 kg·m/s east. Since both magnitude and direction are the same, their momenta are equal.

Which statement accurately describes the model of an explosion based on the provided text?

A) An interaction where external forces cause objects to move apart.

B) An interaction where internal forces cause objects to move apart.

C) An interaction where objects collide and stick together.

D) An interaction where momentum is not conserved.

Correct Answer: B

This is a direct recall of the provided definition: 'An explosion is a model for an interaction in which forces internal to the system move objects within that system apart.'