Change the application point
Compare the same force applied near and far from a chosen pivot.
AP Physics 1 · Unit 5 · Torque and Rotational Dynamics
Torque
Move a force along a lever, change its angle, and measure how force, distance, and direction affect the turning effect.
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Learn by doing
Three ideas you’ll put into motion
Resolve the geometry
Use the perpendicular force component or perpendicular lever arm to calculate torque.
Combine turning effects
Assign clockwise and counterclockwise signs, then test a target net torque.
The big idea
The key ideas, at a glance.
Torque depends on geometry
Torque magnitude is τ = rF sin θ, where θ is the angle between the position vector and force. The pivot must be specified.
Perpendicular distance matters
Equivalently, τ = Fd⊥. A force whose line of action passes through the pivot produces zero torque about that pivot.
A quick comparison
Keep a perpendicular force fixed and double its distance from the pivot.
Torque magnitude 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
- Force vectors, perpendicular components, and basic sine and cosine.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 5: torque, lever arms, and the direction of rotational effects.
- Check for understanding
- Ask why the same force can produce different torques about different pivots.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.