Find a circular orbit
Compare launch conditions and observe the satellite’s path.
AP Physics 1 · Unit 2, Part 2 · Circular Motion and Gravity
Circular Orbits
Launch a satellite and connect gravity, circular speed, and orbital period. Predict how a different orbital radius changes the motion.
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Learn by doing
Three ideas you’ll put into motion
Connect gravity and turning
Use gravitational force as the inward net force for circular motion.
Compare orbital radii
Predict speed and period changes, then check them against the simulated orbit.
The big idea
The key ideas, at a glance.
Gravity provides the inward force
For an ideal circular orbit around mass M, GMm/r2 = mv2/r. The orbiting mass cancels.
Radius controls speed and period
Circular speed is v = √(GM/r). Period is T = 2πr/v; a larger circular orbit is slower and takes longer.
A quick comparison
Compare circular orbits around the same source mass.
Larger radius → lower speed and longer period.
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
- Newton’s gravitation law, circular motion, and algebra with square roots.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 2: gravitation as a model for satellite circular motion.
- Check for understanding
- Ask why a satellite in orbit is accelerating even when its speed is constant.
- Optional extension
- Test more launches in the Circular Orbit lab.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.