Explain the geometry
Measure pivot-to-center length and identify tangential restoring force.
AP Physics 1 · Unit 7 · Oscillations
Period of a Simple Pendulum
Measure pendulum cycles and investigate length, mass, angle and gravity using simultaneous comparisons, then calculate a length for a requested period.
Start lesson- Free
- No account required
- Self-paced
Start guided lesson
Learn by doing
Three ideas you’ll put into motion
Test the model
Run two labeled length, mass, angle or gravity setups together.
Calculate a required length
Use the small-angle period equation and select a multiple-choice answer.
The big idea
The key ideas, at a glance.
Gravity restores motion along the arc
−mg sinθ = maₜ makes mass cancel. For small angles, aₜ ≈ −(g/L)s.
The period model is approximate
T ≈ 2π√(L/g) applies at small angles. Larger angles produce a small increase in period.
A quick comparison
Reduce gravity to one quarter while keeping length fixed.
The small-angle period approximately doubles.
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 second law, force components, small-angle reasoning and spring SHM.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 7: pendulum oscillations, restoring forces and period models.
- Check for understanding
- Ask how to change length to keep the period unchanged in a weaker gravitational field.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.