Unit Overview

Kinematics Overview

AP Physics 1· 5 min read 📊 10-15% of overall AP Physics 1 exam score

1. Unit at a Glance

Kinematics is the starting point for all of physics because it answers the most basic question: how do things move? This unit builds incrementally, starting from core definitions of motion quantities, moving to graphical representations, then algebraic problem-solving, and ending with application to the common real-world case of projectile motion.

Each sub-topic relies on the previous one: you will first master what each motion quantity means, then learn how to visualize motion with graphs, then solve problems with kinematic equations, and finally extend your skills to two-dimensional motion.

This unit includes the following sub-topics, ordered for logical learning:

AP Physics 1 Position, Velocity, and Acceleration

Defines the core vector and scalar quantities used to describe all motion.

★⏱ 6 min

AP Physics 1 Kinematic Graphs

Teaches how to interpret and convert between position-time, velocity-time, and acceleration-time graphs.

★★⏱ 7 min

AP Physics 1 Kinematic Equations for Constant Acceleration

Derives and demonstrates how to apply the core kinematic equations for constant acceleration motion.

★★⏱ 8 min

AP Physics 1 Projectile Motion

Applies kinematic principles to two-dimensional projectile motion by separating independent motion components.

★★★⏱ 8 min

2. Common Pitfalls

Wrong move:

Confusing distance/displacement and speed/velocity, especially when motion reverses direction.

Why:

Distance and speed are scalars (no direction), while displacement and velocity are vectors (include direction).

Correct move:

Always check if a problem asks for a scalar or vector quantity, and account for direction when calculating displacement or average velocity.

Wrong move:

Treating acceleration as automatically positive, regardless of coordinate system.

Why:

Acceleration sign depends on your defined coordinate system, not whether an object is speeding up or slowing down.

Correct move:

Define your positive direction first, then assign the correct sign to acceleration before solving problems.

Wrong move:

Adding horizontal and vertical projectile motion quantities as scalars.

Why:

Horizontal and vertical motion are independent vector components that cannot be added directly as scalars.

Correct move:

Solve for horizontal and vertical quantities separately, then combine them with vector addition if a final resultant is required.

3. Quick Reference Cheatsheet

Concept / Formula	Key Description
$v_{a v g} = \frac{Δ x}{Δ t}$	Average velocity = total displacement divided by elapsed time
$a_{a v g} = \frac{Δ v}{Δ t}$	Average acceleration = total change in velocity divided by elapsed time
$v = v_{0} + a t$	Core constant-acceleration kinematic equation, no displacement term
$Δ x = v_{0} t + \frac{1}{2} a t^{2}$	Core constant-acceleration kinematic equation, relates displacement to time
Projectile motion: $a_{x} = 0, a_{y} = - g$	Horizontal acceleration = 0, vertical acceleration = gravity (downward)

What's Next

Begin this unit with the first sub-topic on core motion quantities, which is the foundation for all other kinematics concepts you will learn. After you complete all four sub-topics in this kinematics unit, you will move on to the next unit on forces and Newton's laws, which connects kinematic motion to its causes.