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AP Physics 1 · Unit 1 · Kinematics

Displacement and Velocity

Change an object’s motion, measure its displacement, and discover why average speed and average velocity can give different answers.

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Displacement and Velocity guided lesson preview Start guided lesson
A real simulation. Guided questions. Feedback as you go.

Learn by doing

Three ideas you’ll put into motion

Measure displacement

Draw a displacement arrow. Compare the path traveled with the change between endpoints.

Connect speed and direction

Reverse velocity and compare position–time graph slopes. See what changes and what stays the same.

Compare whole trips

Use a two-part trip to calculate average speed and average velocity. Check your answers as you go.

The big idea

Same motion. Different measurements.

Distance vs. displacement

Distance adds up the path traveled. Displacement is the change from initial to final position: Δx = xf − xi.

Speed vs. velocity

Speed tells how fast. Velocity includes direction. For a whole trip, average speed uses total distance; average velocity uses displacement. Both divide by total time.

A quick comparison

Move 4 m right, then 1 m left. Take right as positive.

Distance 5 mDisplacement +3 m

Distance and displacement for a trip with a reversal Start at zero meters, move right to four meters, then return left to three meters. The path length is five meters; displacement is positive three meters. 01234 m 4 m right 1 m left +3 m displacement
Teaching this topic?Classroom fit, AP connections, and support
Classroom fit
Use for an introduction to one-dimensional motion, independent practice, or a projected class discussion.
Before students begin
Students should be comfortable with signed numbers, coordinate axes, and simple division. The lesson introduces the physics relationships.
Built-in support
Prepared scenes, guided measurements, conceptual and numerical checks, feedback, and equation help.
AP Physics 1 connections
Scalars and vectors (1.1), displacement and average velocity (parts of 1.2), and position–time graphs (part of 1.3). Course framework.
Check for understanding
Ask students to explain why a completed round trip has zero average velocity even though its average speed is positive.
Optional extension
The separate Constant Speed lab and handout offer more open exploration after the guided lesson.
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Ready to test your thinking?

The first scene is set up. Make a prediction and press Run.

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