AP Physics 1 Unit 2 Review: Force and Translational Dynamics

Q: What's on the AP Physics 1 Unit 2 progress check (MCQ and FRQ)?

The AP Physics 1 Unit 2 progress check includes both MCQ and FRQ parts that test your understanding of force and translational dynamics. The MCQ section pulls from topics like Newton's laws, free-body diagrams, gravitational force, friction, and circular motion. The FRQ part typically asks you to draw and interpret free-body diagrams, apply Newton's Second Law, or analyze a scenario involving kinetic and static friction or spring forces. Working through the progress check is one of the best ways to spot gaps before the real exam. Find matched practice at AP Physics 1 Unit 2 .

Q: How do I practice AP Physics 1 Unit 2 FRQs?

AP Physics 1 Unit 2 FRQs most often focus on free-body diagrams, Newton's Second Law (net force equals mass times acceleration), friction scenarios, and circular motion. Question types include Experimental Design, Qualitative/Quantitative Translation, and Short Answer. To practice, draw a complete free-body diagram for every problem before writing any equations, then show each step of your algebra clearly since College Board awards points for process, not just the final answer. Practice Unit 2 FRQs at AP Physics 1 Unit 2 .

Q: Where can I find AP Physics 1 Unit 2 practice questions?

For AP Physics 1 Unit 2 practice questions, including multiple-choice and practice test sets, head to AP Physics 1 Unit 2 . You'll find MCQs covering Newton's laws, friction, gravitational force, spring forces, and circular motion, plus FRQ practice with worked explanations. Mixing MCQ drills with full free-response attempts is the most effective way to prepare for the 18-23% of the exam this unit represents.

Q: How should I study AP Physics 1 Unit 2?

Start AP Physics 1 Unit 2 by building a strong foundation in free-body diagrams before anything else. Every topic from friction to circular motion depends on correctly identifying and drawing all forces on a system. From there, work through Newton's three laws in order, then apply them to gravitational force, kinetic and static friction, and spring forces before tackling circular motion, which combines several earlier ideas. Here's a practical study sequence: 1. Practice drawing free-body diagrams for simple systems (Topic 2.2) until it feels automatic. 2. Solve Newton's Second Law problems (Topic 2.5) with one force, then layer in friction (Topic 2.7) and gravitational force (Topic 2.6). 3. Work circular motion problems (Topic 2.9) by identifying the net centripetal force from your free-body diagram. 4. Do timed FRQ practice and check that every step of your algebra is visible on paper. All topics and practice sets are at AP Physics 1 Unit 2 .

18–23% of AP multiple choice
9 topics
AP exam review verified for 2027

Force and Translational Dynamics is the study of how forces between objects determine whether a system accelerates, stays at constant velocity, or moves in a curved path. The unit introduces Newton's three laws, gravitational and contact forces, friction, spring forces, and circular motion, all analyzed through free-body diagrams and vector equations.

Fiveable's AP Physics 1 Unit 2 review covers 9 topics, with guided practice questions for the unit.

start with 2.1 start unit practiceReview with a tutorFree, 24/7, real people, from UPchieve

AP Physics 1 unit 2 topics

2.1

Systems and Center of Mass

Define a system, distinguish internal from external forces, and calculate the center of mass position using x_cm = (sum m_i x_i)/(sum m_i). Symmetric objects have their center of mass on the symmetry axis.

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2.2

Forces and Free-Body Diagrams

Represent every external force on an object as a vector arrow from a center-of-mass dot. Choose a coordinate system aligned with the acceleration direction to simplify force equations.

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2.3

Newton's Third Law

Every force has a paired force equal in magnitude and opposite in direction acting on the other object. Ideal strings have uniform tension; ideal pulleys redirect force without changing its magnitude.

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2.4

Newton's First Law

When the net force on a system is zero, its velocity is constant (translational equilibrium). This applies to objects at rest and objects moving at constant velocity in an inertial reference frame.

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2.5

Newton's Second Law

A nonzero net external force causes the center of mass to accelerate: a_sys = F_net / m_sys. Apply this axis by axis using the free-body diagram to find unknown forces or accelerations.

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2.6

Gravitational Force

Gravitational force between two masses follows F_g = G m_1 m_2 / r^2. Near Earth's surface, weight = mg. Apparent weight equals the normal force and changes when an object accelerates vertically.

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2.7

Kinetic and Static Friction

Kinetic friction has fixed magnitude F_f,k = mu_k N and opposes sliding. Static friction adjusts up to F_f,s,max = mu_s N to prevent sliding. Both depend on the normal force, not contact area.

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2.8

Spring Forces

Hooke's law: F_s = -k delta x. The spring constant k (N/m) measures stiffness, and the restoring force always points toward the equilibrium position regardless of whether the spring is stretched or compressed.

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2.9

Circular Motion

Centripetal acceleration a_c = v^2/r points inward and is produced by real forces. Identify which forces contribute inward net force. For satellites, Kepler's third law T^2 = (4 pi^2/GM) R^3 connects period and orbital radius.

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Practice AP Physics 1 unit 2 questions

Try AP-style questions on unit 2, then use the review notes below for anything you miss.

Example stimulus-based MCQs

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setup_diagram

Stimulus-based practice question

Two crates, Crate A of mass 40 kg and Crate B of mass 60 kg, are connected by a light cable. A vertical upward force of 1200 N is applied to Crate A, as shown in the figure.

answer in practice

Question

Which of the following is most nearly the tension in the cable connecting the crates?

480 N

600 N

720 N

1200 N

setup_diagram

Stimulus-based practice question

A $10 \text{ kg}$ block on a rough horizontal surface is pulled by a string at an angle of $37^\circ$ above the horizontal with a constant tension of $50 \text{ N}$ , as shown in the figure. The coefficient of kinetic friction between the block and the surface is $0.20$ .

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Question

If the block starts from rest, which of the following is most nearly its speed after moving $5.0 \text{ m}$ ?

$4.5 \text{ m/s}$

$5.1 \text{ m/s}$

$6.0 \text{ m/s}$

$6.3 \text{ m/s}$

Example FRQs

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FRQ

Circular motion friction on rotating platform

1. A student places two small blocks A and B on a horizontal rotating turntable, as shown in Figure 1. The turntable rotates with angular speed $\omega$ about a vertical axis through its center. Block A of mass $m_A = 0.40\ \text{kg}$ is at radius $r_A = 0.20\ \text{m}$ , and block B of mass $m_B = 0.80\ \text{kg}$ is at radius $r_B = 0.50\ \text{m}$ . The coefficient of static friction between each block and the turntable is $\mu_s = 0.60$ , and the coefficient of kinetic friction is $\mu_k = 0.40$ . Assume the blocks are small enough to be treated as point masses, and ignore air resistance.

Figure 1. Top view of a horizontal rotating turntable with two point-like blocks at specified radii; counterclockwise rotation with angular speed ω.

Figure 2. Blank axes for graphing maximum static friction force versus radius on a horizontal turntable.

On the axes shown in Figure 2, sketch a graph of the maximum possible static friction force $f_{s,\max}$ on a single block as a function of its radius $r$ on the horizontal turntable.

ii.

Derive an expression for the angular speed $\omega_{B,\text{slip}}$ at which block B begins to slip in terms of $\mu_s$ , $g$ , and $r_B$ , as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

iii.

Derive an expression for the angular speed $\omega_{A,\text{slip}}$ at which block A would begin to slip in terms of $\mu_s$ , $g$ , and $r_A$ , as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

Indicate whether the magnitude of the friction force exerted by the turntable on block B is equal to, less than, or greater than the magnitude of the friction force exerted by block B on the turntable. At $t=t_1$ , block B has just begun to slip outward relative to the turntable, while block A is still not slipping. Consider the interaction forces between block B and the turntable at that instant.

Equal to
Less than
Greater than
Justify your response.

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FRQ

Static friction on rotating platform scenarios

4. In Scenario 1, a small block of mass $m=0.50\ \text{kg}$ rests on a horizontal rotating platform at a distance $R=0.30\ \text{m}$ from the platform's axis of rotation, as shown in Figure 1. The coefficient of static friction between the block and the platform is $\mu_{s1}=0.60$ . The platform rotates at a constant angular speed $\omega_1=3.0\ \text{rad/s}$ , and the block remains at rest relative to the platform.

In Scenario 2, the same block is placed at the same distance $R$ on a different horizontal rotating platform, as shown in Figure 2. The coefficient of static friction between the block and the platform is $\mu_{s2}=0.30$ . The platform rotates at a constant angular speed $\omega_2=2.0\ \text{rad/s}$ , and the block remains at rest relative to the platform.

Figure 1. Scenario 1: Block on a horizontal rotating platform (top view and side view) with R = 0.30 m, m = 0.50 kg, μs1 = 0.60, and ω1 = 3.0 rad/s.

Figure 2. Scenario 2: Block on a different horizontal rotating platform (top view and side view) with R = 0.30 m, m = 0.50 kg, μs2 = 0.30, and ω2 = 2.0 rad/s.

Refer to Figure 2. Refer to Figure 1. Indicate whether the magnitude of the static friction force exerted on the block in Scenario 1, $f_{s1}$ , is greater than, less than, or equal to the magnitude of the static friction force exerted on the block in Scenario 2, $f_{s2}$ , by writing one of the following in your answer booklet.

• $f_{s1} > f_{s2}$
• $f_{s1} < f_{s2}$
• $f_{s1} = f_{s2}$

Justify your answer in terms of ALL forces exerted on the block in each scenario. Use qualitative reasoning beyond referencing equations.

Starting with Newton's second law, derive an expression for the magnitude of the static friction force $f_s$ exerted on the block while it remains at rest relative to the platform. Express your answer in terms of $m$ , $R$ , and $\omega$ and physical constants, as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information. Consider the general case where a block of mass $m=0.50\ \text{kg}$ is at rest relative to a horizontal rotating platform at a distance $R=0.30\ \text{m}$ from the axis while the platform rotates at constant angular speed $\omega$ .

Indicate whether the expression for $f_s$ you derived in part B is or is not consistent with the claim made in part A. Briefly justify your answer by referencing your derivation in part B.

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FRQ

Kinetic friction coefficient determination through acceleration measurement

3. Students are investigating the motion of a system consisting of a block on a horizontal surface connected by a light string over a low-friction pulley to a hanging mass, as shown in Figure 1. The students want to determine the coefficient of kinetic friction between the block and the surface.

Figure 1. Block-pulley apparatus for friction measurement

Describe an experimental procedure to collect data that would allow the students to determine μk between the block and the table. Include the measurements the students should take, and include at least one specific step the students should take to reduce experimental uncertainty.

Figure 3. Apparatus with free-body diagrams

The students model the block–hanging-mass system as follows. The block of mass mB experiences kinetic friction fk = μkN, with N = mBg. Using Figure 3, applying Newton's second law to each object and eliminating the string tension leads to the relationship

mH = μk mB + (mB + mH),a/g

where g = 9.80 m/s^2.

Describe how the students could use measurements of mH and a for several trials to create a linear graph and how the slope of that graph could be used to determine μk.

Figure 2. Grid for linearized relationship plot

mH (kg)	a (m/s^2)
0.080	0.24
0.100	0.60
0.120	0.88
0.140	1.18
0.160	1.44

mH (kg)	a (m/s^2)	a/(g − a) (dimensionless)
0.080	0.24
0.100	0.60
0.120	0.88
0.140	1.18
0.160	1.44

The students perform five trials using mB = 0.500 kg and vary the hanging mass mH. For each trial, the system is released from rest and the acceleration a of the block is measured with the motion sensor while the block moves 1.20 m. The measured values are shown in Table 1.

The students decide to create a graph with a/(g − a) on the horizontal axis. Use g = 9.80 m/s^2.

Indicate what measured or calculated quantity could be plotted on the vertical axis to yield a linear graph.

Vertical axis: Horizontal axis: a/(g − a)

ii.

On the blank grid provided in Figure 2, create a graph of the quantities indicated in part C(i).

•

Use Table 2 to record the calculated values of a/(g − a) that you will plot.

•

Clearly label the vertical axis, including units as appropriate.

•

Plot the points you recorded in Table 2.

iii.

Draw a straight best-fit line for the data graphed in part C(ii).

Using the best-fit line that you drew in part C(iii), calculate an experimental value for the coefficient of kinetic friction μk between the block and the table. Clearly indicate how you obtained the slope from your graph and how the slope is related to μk.

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AP Physics 1 unit 2 practice test

A timed, AP-style test built only from unit 2 questions — multiple choice plus free response, scored with AI feedback. Use the standard format or build your own.

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Unit 2 review notes

2.1

Systems and Center of Mass

A system is any object or group of objects you choose to analyze together. Internal forces between parts of the system do not change the motion of the system's center of mass; only external forces do. The center of mass is the mass-weighted average position of the system, and you can treat the entire system as a single particle located there.

Center of mass formula: x_cm = (sum of m_i x_i) / (sum of m_i); for symmetric mass distributions, the center of mass lies on the axis of symmetry.
Internal vs. external forces: Internal forces act between parts within the system and cancel in pairs; external forces from the environment can accelerate the center of mass.
System as a single particle: When internal structure does not matter for the question, treat the whole system as one object located at its center of mass.
System boundary: Choosing the boundary determines which forces are internal and which are external, directly affecting your force equations.

Given three masses on a number line, can you calculate the x-coordinate of the center of mass and explain why an internal explosion between them would not move the center of mass?

Feature	Internal Force	External Force
Source	Between objects inside the system	From an object outside the system
Effect on center of mass	None; they cancel in Newton's third law pairs	Accelerates the center of mass
Appears on system FBD?	No	Yes

2.2

Forces and Free-Body Diagrams

A force is a vector interaction between two objects. Free-body diagrams (FBDs) show every external force on one chosen object as an arrow starting from a dot representing the center of mass. Drawing a correct FBD is the first step in applying any of Newton's laws.

Force as a vector: Forces have magnitude and direction; they must be added as vectors, not scalars.
Contact forces: Normal force, friction, and tension arise from surfaces or strings touching the object; they are macroscopic results of interatomic electric forces.
FBD rules: Draw one dot for the object, then draw each external force as a straight arrow from that dot. Do not include internal forces or forces the object exerts on other things.
Coordinate system choice: Align one axis with the direction of acceleration (e.g., along an incline surface) to minimize the number of force components you need to resolve.
Net force: The vector sum of all forces on the object; determines whether the object accelerates and in which direction.

Draw the FBD for a block on a frictionless inclined plane. Which forces appear, and how do you set up your coordinate axes to simplify the equations?

Force type	Symbol	Direction	When it acts
Weight	mg or F_g	Straight down toward Earth	Always, on any object with mass
Normal force	F_n	Perpendicular to and away from surface	When object contacts a surface
Tension	T	Along string, away from object	When object is connected to a string or rope
Friction	F_f	Parallel to surface, opposing relative motion or tendency	When surfaces are in contact
Spring force	F_s = -k delta x	Toward equilibrium position	When object is attached to a spring

2.3

Newton's Third Law and Paired Forces

Newton's third law states that when object A exerts a force on object B, object B exerts an equal and opposite force on object A. These paired forces always act on different objects, so they never cancel each other on a single free-body diagram. Ideal strings transmit tension uniformly; ideal pulleys redirect force without changing its magnitude.

Third law pair notation: F_A on B = -F_B on A; equal in magnitude, opposite in direction, same type of force, acting on different objects.
Paired forces on different objects: Because each force in a pair acts on a different object, they appear on different free-body diagrams and cannot cancel on either one.
Internal forces and center of mass: Forces between objects inside a chosen system are internal; they do not change the acceleration of the system's center of mass.
Ideal string: Massless and inextensible; tension is the same at every point along the string.
Ideal pulley: Massless and frictionless; it redirects the tension force without changing its magnitude.

A horse pulls a cart. Explain why the horse-cart system accelerates even though the horse and cart exert equal and opposite forces on each other.

Property	Ideal string	String with nonnegligible mass
Mass	Negligible (zero)	Has measurable mass
Tension along length	Same at all points	Varies along the string
Used in AP Physics 1	Yes, standard assumption	Qualitative reasoning only

2.4

Newton's First and Second Laws

Newton's first law: if the net force on a system is zero, its velocity stays constant (translational equilibrium). Newton's second law: if the net force is nonzero, the center of mass accelerates in the direction of that net force, with magnitude a = F_net / m_sys. These two laws cover every translational motion scenario in the unit.

Translational equilibrium: Sum of all forces equals zero in every direction; the object is either at rest or moving at constant velocity.
Newton's second law: a_sys = F_net / m_sys; acceleration is in the same direction as the net external force and proportional to its magnitude.
Inertial reference frame: A frame in which Newton's first law holds; an observer in this frame sees no fictitious forces.
Unbalanced forces: When the vector sum of forces is not zero, the system's velocity changes; the change is only in the direction of the net force.
Axis-by-axis application: Apply sum F_x = m a_x and sum F_y = m a_y separately; forces balanced in one direction do not affect acceleration in the other.

A 5 kg block on a frictionless surface has a 20 N force applied horizontally and a 10 N force applied in the opposite direction. What is the acceleration, and in which direction?

Condition	Net Force	Velocity	Acceleration
Static equilibrium	Zero	Zero (at rest)	Zero
Dynamic equilibrium	Zero	Constant, nonzero	Zero
Accelerating system	Nonzero	Changing	Nonzero, same direction as F_net

2.6

Gravitational Force

Newton's law of universal gravitation gives the attractive force between any two masses: F_g = G m_1 m_2 / r^2. Near Earth's surface, the gravitational field is approximately uniform at g = 10 N/kg, so weight = mg. Apparent weight (the normal force you feel) differs from true weight whenever you accelerate vertically.

Universal gravitation: F_g = G m_1 m_2 / r^2; force is attractive, acts along the line connecting centers of mass, and follows an inverse-square relationship with distance.
Gravitational field strength: g = G M / r^2; near Earth's surface g is approximately 10 N/kg, giving weight = mg.
Apparent weight: The normal force on an object; equals mg only when acceleration is zero. In an accelerating elevator, N = m(g plus or minus a).
Gravitational vs. inertial mass: Both are equivalent for AP Physics 1 purposes; the same mass appears in F = ma and F_g = mg.

An astronaut in a freely falling spacecraft feels weightless. Explain using gravitational force and apparent weight why this occurs even though gravity is still acting.

2.7

Kinetic and Static Friction

Friction is a contact force parallel to the surface. Kinetic friction acts when surfaces slide relative to each other and has a fixed magnitude. Static friction acts when surfaces are not sliding and adjusts up to a maximum value to prevent motion. Neither type depends on the area of contact.

Kinetic friction: F_f,k = mu_k times F_n; acts opposite to the direction of relative motion between surfaces.
Static friction: F_f,s is less than or equal to mu_s times F_n; adjusts to match the applied force until the maximum is reached, then the object slips.
Maximum static friction: F_f,s,max = mu_s times F_n; once the applied force exceeds this value, the object begins to slide and kinetic friction takes over.
Normal force dependence: Both friction forces scale with the normal force, not the contact area; on an incline, the normal force is F_n = mg cos(theta).
mu_s vs. mu_k: The coefficient of static friction is typically greater than the coefficient of kinetic friction for the same pair of surfaces.

A 10 kg box sits on a surface with mu_s = 0.5 and mu_k = 0.3. What is the minimum horizontal force needed to start the box moving, and what friction force acts once it is sliding?

Property	Static Friction	Kinetic Friction
When it acts	Surfaces not sliding relative to each other	Surfaces sliding relative to each other
Magnitude	Adjusts; F_f,s is less than or equal to mu_s F_n	Fixed; F_f,k = mu_k F_n
Direction	Opposes tendency of motion	Opposes direction of relative motion
Coefficient	mu_s (typically larger)	mu_k (typically smaller)

2.8

Spring Forces and Hooke's Law

An ideal spring exerts a restoring force proportional to its displacement from its relaxed length: F_s = -k delta x. The negative sign means the force always points back toward the equilibrium position. The spring constant k (units: N/m) measures stiffness; a steeper slope on a force-vs-displacement graph means a stiffer spring.

Hooke's law: F_s = -k delta x; delta x is measured from the relaxed (natural) length, and the force direction is always toward equilibrium.
Spring constant k: Measured in N/m; equals the slope of a force-vs-displacement graph. Larger k means a stiffer spring.
Restoring force: The spring force always acts to return the object to the equilibrium position, whether the spring is stretched or compressed.
Ideal spring assumptions: Negligible mass, does not stretch permanently; force is strictly proportional to displacement within the elastic range.

A spring with k = 200 N/m is compressed 0.05 m from its relaxed length. What is the magnitude and direction of the force it exerts on the attached object?

2.9

Circular Motion and Kepler's Third Law

An object moving in a circle has centripetal acceleration directed toward the center: a_c = v^2/r. This acceleration is produced by the net inward component of real forces (gravity, tension, normal force, friction). For vertical loops, the critical minimum speed at the top occurs when gravity alone provides the centripetal force. For satellites in circular orbit, Kepler's third law relates period and orbital radius to the mass of the central body.

Centripetal acceleration: a_c = v^2/r; always directed toward the center of the circular path; it is not a new force but the result of real forces.
Net centripetal force: The vector sum of all real forces on the object must equal m times v^2/r directed inward; identify which forces contribute inward and which point outward.
Minimum speed at top of loop: At the top of a vertical loop, gravity alone provides centripetal force at minimum speed: v_min = sqrt(g r).
Banked surface: On a banked curve, components of the normal force and static friction together supply the centripetal force; the bank angle reduces reliance on friction.
Kepler's third law: T^2 = (4 pi^2 / GM) R^3; for a satellite in circular orbit, the square of the period is proportional to the cube of the orbital radius, with M being the mass of the central body.

A car travels over the top of a circular hill of radius r at speed v. Write the Newton's second law equation for the car at that point and determine the normal force on the car.

Scenario	Forces providing centripetal acceleration	Key equation
Horizontal circle on flat road	Static friction inward	mu_s m g = m v^2/r
Top of vertical loop	Gravity plus normal force (both inward)	mg + N = m v^2/r
Bottom of vertical loop	Normal force inward, gravity outward	N - mg = m v^2/r
Satellite in circular orbit	Gravity only	G M m / r^2 = m v^2/r
Banked curve (no friction)	Normal force component inward	N sin(theta) = m v^2/r

Key terms

Term	Definition
system-environment interaction	The exchange of energy or mass between a chosen system and its surroundings; external forces from the environment can change the motion of the system's center of mass, while internal forces cannot.
system equation	An equation describing the motion of an entire system by applying Newton's second law with the total system mass and the net external force; internal forces cancel and do not appear.
Newton's law of universal gravitation	F_g = G m_1 m_2 / r^2; the gravitational force between two masses is attractive, acts along the line connecting their centers of mass, and decreases with the square of the distance between them.
tangential speed	The instantaneous speed of an object moving along a circular path, directed tangent to the circle at that point; used with radius to calculate centripetal acceleration via a_c = v^2/r.
banked surface	An inclined circular path where the normal force component directed inward, and sometimes static friction, together supply the net centripetal force needed for circular motion.
Kepler's third law	T^2 = (4 pi^2 / GM) R^3; for a satellite in circular orbit, the square of the orbital period is proportional to the cube of the orbital radius, with M being the mass of the central body.
orbital period	The time T for a satellite to complete one full revolution in a circular orbit; related to orbital radius and central body mass by Kepler's third law.
orbital radius	The distance R from the center of the central body to the orbiting satellite; determines both the gravitational force on the satellite and its orbital period via Kepler's third law.

How to review unit 2

Topics students miss most

Miss rates come from Fiveable multiple-choice practice.

2.1

Systems and Center of Mass

47%2,041 tries

2.9

Circular Motion

44%1,647 tries

2.7

Kinetic and Static Friction

40%2,242 tries

Common unit 2 mistakes

Treating Newton's third law pairs as canceling on one object

Third-law paired forces act on different objects. They appear on different free-body diagrams and never cancel each other. Only forces on the same object can cancel when finding net force.

Using the wrong normal force in friction problems

On an inclined plane, the normal force is mg cos(theta), not mg. Always resolve weight into components perpendicular and parallel to the surface before writing friction equations.

Confusing centripetal force with a separate force

Centripetal force is not a new force you add to the free-body diagram. It is the label for the net inward force produced by real forces already on the diagram, such as gravity, tension, or friction.

Forgetting that static friction is an inequality

Static friction adjusts to whatever value is needed to prevent sliding, up to mu_s times N. It is not always at its maximum value; only set F_f,s = mu_s N when the object is on the verge of slipping.

Applying Hooke's law with displacement from the wrong reference point

Delta x in F_s = -k delta x is measured from the spring's relaxed (natural) length, not from an arbitrary position. Measuring from the wrong reference gives the wrong force magnitude and direction.

How this unit shows up on the AP exam

Free-body diagram construction and justification

AP Physics 1 frequently asks you to draw a free-body diagram for a specific object in a multi-object scenario, label each force with its type and agent, and then use the diagram to write Newton's second law equations. You may also be asked to explain why a particular force does or does not appear, or to compare diagrams for two objects interacting via Newton's third law.

Quantitative-qualitative translation tasks

A common task pattern presents a physical scenario and asks you to predict how a change in one variable (mass, applied force, surface angle, orbital radius) affects another quantity (acceleration, friction force, normal force, orbital period). You need to reason from the relevant equation and explain the direction of the change, not just calculate a number.

Multi-representation reasoning across force contexts

Exam questions often require you to move between a written description, a free-body diagram, and an algebraic equation within a single problem. Circular motion and inclined-plane problems in particular require you to identify which real forces contribute to the net centripetal or net parallel force, set up the correct Newton's second law equation, and interpret the result in terms of the physical situation.

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Frequently Asked Questions

What's on the AP Physics 1 Unit 2 progress check (MCQ and FRQ)?

The AP Physics 1 Unit 2 progress check includes both MCQ and FRQ parts that test your understanding of force and translational dynamics. The MCQ section pulls from topics like Newton's laws, free-body diagrams, gravitational force, friction, and circular motion. The FRQ part typically asks you to draw and interpret free-body diagrams, apply Newton's Second Law, or analyze a scenario involving kinetic and static friction or spring forces. Working through the progress check is one of the best ways to spot gaps before the real exam. Find matched practice at AP Physics 1 Unit 2.

How do I practice AP Physics 1 Unit 2 FRQs?

AP Physics 1 Unit 2 FRQs most often focus on free-body diagrams, Newton's Second Law (net force equals mass times acceleration), friction scenarios, and circular motion. Question types include Experimental Design, Qualitative/Quantitative Translation, and Short Answer. To practice, draw a complete free-body diagram for every problem before writing any equations, then show each step of your algebra clearly since College Board awards points for process, not just the final answer. Practice Unit 2 FRQs at AP Physics 1 Unit 2.

Where can I find AP Physics 1 Unit 2 practice questions?

For AP Physics 1 Unit 2 practice questions, including multiple-choice and practice test sets, head to AP Physics 1 Unit 2. You'll find MCQs covering Newton's laws, friction, gravitational force, spring forces, and circular motion, plus FRQ practice with worked explanations. Mixing MCQ drills with full free-response attempts is the most effective way to prepare for the 18-23% of the exam this unit represents.

How should I study AP Physics 1 Unit 2?

Start AP Physics 1 Unit 2 by building a strong foundation in free-body diagrams before anything else. Every topic from friction to circular motion depends on correctly identifying and drawing all forces on a system. From there, work through Newton's three laws in order, then apply them to gravitational force, kinetic and static friction, and spring forces before tackling circular motion, which combines several earlier ideas. Here's a practical study sequence:
1. Practice drawing free-body diagrams for simple systems (Topic 2.2) until it feels automatic.
2. Solve Newton's Second Law problems (Topic 2.5) with one force, then layer in friction (Topic 2.7) and gravitational force (Topic 2.6).
3. Work circular motion problems (Topic 2.9) by identifying the net centripetal force from your free-body diagram.
4. Do timed FRQ practice and check that every step of your algebra is visible on paper. All topics and practice sets are at AP Physics 1 Unit 2.

Ready to review Unit 2?Start with the notes, check the topic cards, and use the practice or resource links when they are available for this course.

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