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AP Physics 1: Algebra-Based Practice Quiz: Newton's Second Law

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

Test your understanding with short quizzes. This quiz has 10 questions to check your progress.

Question 1 of 10

Based on the provided content, what is the definition of "unbalanced forces"?

All Questions (10)

Based on the provided content, what is the definition of "unbalanced forces"?

A) A configuration of forces where the net force is zero.

B) A configuration of forces such that the net force exerted on a system is not equal to zero.

C) Forces that cause a system to remain at rest.

D) Forces that are equal in magnitude and opposite in direction.

Correct Answer: B

The content explicitly states, "Unbalanced forces are a configuration of forces such that the net force exerted on a system is not equal to zero."

According to the provided text, what is the sole condition required for the velocity of a system's center of mass to change?

A) The system must have a large mass.

B) At least two forces must be acting on the system.

C) A nonzero net external force must be exerted on the system.

D) The system must be in motion initially.

Correct Answer: C

The text states, "The velocity of a system's center of mass will only change if a nonzero net external force is exerted on that system."

Newton's second law of motion, as described in the text, establishes a relationship between the direction of a system's acceleration and the direction of the net force. What is this relationship?

A) They are in opposite directions.

B) They are perpendicular to each other.

C) They are in the same direction.

D) There is no consistent relationship between their directions.

Correct Answer: C

The content specifies that the acceleration of a system's center of mass "...is in the same direction as that net force."

Based on the statement of Newton's second law, how does the magnitude of a system's acceleration relate to the magnitude of the net force exerted on it?

A) The acceleration's magnitude is inversely proportional to the net force's magnitude.

B) The acceleration's magnitude is proportional to the net force's magnitude.

C) The acceleration's magnitude is equal to the net force's magnitude.

D) There is no direct relationship between the two magnitudes.

Correct Answer: B

The text states that the acceleration of a system's center of mass "has a magnitude proportional to the magnitude of the net force exerted on the system."

A system is observed to be moving with a constant velocity. Based on the provided principles, what can be concluded about the net force on the system?

A) The net force is nonzero and in the direction of motion.

B) The net force is nonzero and opposite the direction of motion.

C) The net force must be equal to zero.

D) The net force is changing over time.

Correct Answer: C

Constant velocity means the velocity is not changing. The text states, "The velocity of a system's center of mass will only change if a nonzero net external force is exerted on that system." Therefore, if the velocity is not changing, the net force must be zero.

If a system is subjected to a nonzero net external force, which of the following must be true for the system's center of mass?

A) Its velocity must be zero.

B) Its velocity must be constant.

C) Its velocity must change.

D) Its position must not change.

Correct Answer: C

The content directly states that "the velocity of a system's center of mass will only change if a nonzero net external force is exerted on that system." Therefore, the presence of such a force guarantees a change in velocity.

A system experiences a configuration of forces such that the net force is not equal to zero. According to the provided information, what is the direct consequence for the system's center of mass?

A) It will remain at rest.

B) It will move at a constant, non-zero velocity.

C) It will accelerate.

D) Its mass will change.

Correct Answer: C

The text defines a non-zero net force as "unbalanced forces." It then states that a non-zero net force causes an acceleration. A change in velocity is acceleration, which is the direct consequence.

Which of the following statements accurately describes a key aspect of Newton's second law as presented in the provided text?

A) The acceleration of a system is inversely proportional to its mass.

B) The net force on a system is equal to the rate of change of its momentum.

C) The acceleration of a system's center of mass is proportional in magnitude to the net force.

D) For every action, there is an equal and opposite reaction.

Correct Answer: C

The text explicitly states that "the acceleration of a system's center of mass has a magnitude proportional to the magnitude of the net force exerted on the system." Options A, B, and D describe other valid physics principles, but they are not mentioned in the provided content.

If the acceleration of a system's center of mass is zero, what can be inferred about the net force acting on the system?

A) The net force is a large, constant value.

B) The net force is zero.

C) The net force is acting perpendicular to the system's velocity.

D) There is not enough information to determine the net force.

Correct Answer: B

According to Newton's second law as described, acceleration is proportional to the net force. If the acceleration is zero, the proportional net force must also be zero. This is the logical inverse of the statement that a nonzero net force causes acceleration.

A change in a system's velocity is directly caused by which of the following, according to the provided text?

A) The presence of any single force.

B) The system possessing a large mass.

C) A nonzero net external force.

D) The system having an initial velocity.

Correct Answer: C

The text states, "The velocity of a system's center of mass will only change if a nonzero net external force is exerted on that system." This establishes the direct causal link between a nonzero net force and a change in velocity.