Compare different paths
Observe how gravity’s work depends on endpoints rather than the route between them.
AP Physics 1 · Unit 3 · Work, Energy, and Power
Conservative Forces and Gravitational Potential Energy
Compare paths and heights to explain gravitational work, conservative forces, and changes in gravitational potential energy.
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Learn by doing
Three ideas you’ll put into motion
Choose a reference height
Connect a height change with gravitational potential energy.
Follow the energy transfer
Use work and energy signs to explain rising and falling motion.
The big idea
The key ideas, at a glance.
Gravity is conservative
Between the same two heights, gravity does the same work regardless of path. A closed trip gives zero net work by gravity.
Height changes potential energy
Near Earth with constant g, Ug = mgy for a chosen zero height. Gravity’s work is Wg = −ΔUg.
A quick comparison
Raise the same object to the same height using two different routes.
The change in gravitational potential energy is the same.
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
- Work, kinetic energy, mass, and vertical position.
- Built-in support
- Prepared scenes, guided prompts, and feedback on lesson questions.
- AP Physics 1 connections
- Unit 3: conservative interactions and gravitational potential energy.
- Check for understanding
- Ask why changing the zero of potential energy does not change ΔU for a trip.
- Optional extension
- Explore energy changes in the Skater Bowl lab.
Ready to test your thinking?
The first scene is set up. Start the lesson and explore.