Follow the loop
Observe how height, speed, and force directions change around the track.
AP Physics 1 · Unit 2, Part 2 · Circular Motion and Gravity
Vertical Circular Motion
Follow an object around a vertical loop and compare speed, contact force, and acceleration at the bottom, side, and top.
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- Self-paced
Start guided lesson
Learn by doing
Three ideas you’ll put into motion
Build the radial equation
Use the actual forces and choose inward separately at each position.
Test continued contact
Change the entry conditions and investigate when the object leaves the inside track.
The big idea
The key ideas, at a glance.
Inward changes direction
At the top of an inside loop, both gravity and the normal force can point inward. At the bottom, they oppose one another.
Reaching the top is not enough
Continued contact requires a nonnegative normal force. At the top contact limit, N = 0 and v2 = gr.
A quick comparison
Consider the top of an inside loop at the contact limit.
Gravity supplies all the inward force.
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
- Circular motion, force diagrams, and conservation of mechanical energy for a frictionless track.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 2 circular dynamics, with Unit 3 energy connections.
- Check for understanding
- Ask why zero normal force at the top does not mean zero acceleration.
- Optional extension
- Explore the Vertical Circular Motion lab.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.