Unit Overview
Dynamics Overview
AP Physics 1Β· 5 min read π 12-18% of full AP Physics 1 exam
1. Unit at a Glance
We build this unit from the ground up, starting with the fundamentals of each of Newton's three laws. We begin with the concept of inertia (First Law), move to the core relationship between net force, mass, and acceleration (Second Law), then cover action-reaction pairs (Third Law). Along the way you will master free-body diagrams, the most important tool for solving any force problem.
After covering core laws and individual common forces (gravity, weight, friction, tension), we apply these concepts to common exam problem scenarios, including inclined planes, Atwood machines, and multi-object system models. This sequence progresses from foundational concepts to applied problem solving, aligned directly with how the AP Physics 1 exam tests these topics.
Below are all sub-topics in this unit, ordered by learning progression:
AP Physics 1 Newton's First Law
Understand inertia and the conditions for translational equilibrium.
β β β± 6 min
AP Physics 1 Newton's Second Law
Master the core dynamics relationship for non-equilibrium motion.
β β β β± 7 min
AP Physics 1 Newton's Third Law and Free-Body Diagrams
Identify action-reaction pairs and learn to draw accurate free-body diagrams.
β β β β± 8 min
AP Physics 1 Gravitational Force and Weight
Distinguish between mass and weight, and calculate gravitational force near Earth's surface.
β β β± 5 min
AP Physics 1 Friction and Tension
Learn to model static/kinetic friction and calculate tension in strings and ropes.
β β β β± 8 min
AP Physics 1 Inclined Planes and Atwood Machines
Apply Newton's laws to solve standard force problems for two common classic systems.
β β β β β± 10 min
AP Physics 1 System Models
Treat multiple connected objects as a single system to simplify force calculations.
β β β β β± 7 min
2. Common Pitfalls
Wrong move:
Confusing action-reaction force pairs with forces acting on the same object
Why:
Action-reaction pairs always act on two different objects, so they never cancel out on a single object
Correct move:
Always confirm which object each force acts on when identifying third-law pairs
Wrong move:
Forgetting to resolve gravity into components when working on inclined planes
Why:
Net force calculations require all forces to align with your chosen coordinate system
Correct move:
Always split gravity into parallel and perpendicular components relative to the incline surface
Wrong move:
Assuming tension always equals the weight of a hanging object
Why:
Tension only equals weight for systems in equilibrium (acceleration = 0)
Correct move:
Use Newton's second law to calculate tension for accelerating systems
3. Quick Reference Cheatsheet
Concept / Formula | Key Description |
|---|---|
Newton's Second Law: | Core equation for all dynamics problems: net force equals mass times acceleration |
Weight: | Gravitational force on an object near Earth's surface, |
Kinetic Friction: | Magnitude of kinetic friction, proportional to normal force and friction coefficient |
Static Friction: | Static friction adjusts to match applied force, up to a maximum threshold value |
Newton's First Law | Objects maintain constant velocity if and only if net force acting on them equals zero |
Newton's Third Law | For every force exerted by A on B, there is an equal magnitude opposite direction force exerted by B on A |
What's Next
Start with the first sub-topic of this unit to begin learning dynamics from the foundational level up. Once you complete all sub-topics in Dynamics, move on to the next unit to continue building your AP Physics 1 mechanics knowledge.