Combine two motions
Observe translation and rotation separately, then combine their velocity contributions.
AP Physics 1 · Unit 5 · Torque and Rotational Dynamics
Rolling Motion
Separate translation from rotation, track points on a wheel, and test the condition for rolling without slipping.
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Learn by doing
Three ideas you’ll put into motion
Track the contact point
Compare the wheel’s top, center, and bottom in the ground reference frame.
Match the rolling condition
Change linear and angular velocity and investigate slipping and contact friction.
The big idea
The key ideas, at a glance.
No-slip rolling links speeds
The center speed and angular speed satisfy vCM = R|ω| for rolling on a stationary surface. This is a contact condition.
A point’s velocity combines contributions
At an instant of no-slip rolling, the bottom point is at rest relative to the ground. The top point moves at twice the center speed.
A quick comparison
Watch a wheel roll without slipping over stationary ground.
Contact point: instantaneous ground-frame speed zero.
Teaching this topic?Classroom fit, AP connections, and support
- Classroom fit
- Use for a concept introduction, guided independent practice, or a projected class discussion.
- Before students begin
- Angular kinematics, velocity-vector addition, and static and kinetic friction.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 5: relating linear and rotational motion and interpreting contact conditions.
- Check for understanding
- Ask why a point that is momentarily at rest at the bottom does not stay at rest.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.