Gravitational Potential Energy
Lesson notes
Overview
Potential energy near a planet is negative and rises toward zero at infinity. This topic is rated beginner and is number 132 of 227 in Physics. Core ideas and first intuitions. No prior knowledge needed.
What you are seeing
The panel above shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
Near a planet the potential energy is U = −GMm/r, which is negative because gravity is attractive and we set the zero at infinity. It rises toward zero as the object moves away. Total energy, kinetic plus potential, decides the orbit: negative means bound, so an ellipse or circle; zero is the parabolic escape path; positive means a hyperbola. The familiar mgh is just the change in this energy near the surface.
Reading the relationship
The expression "U = −GMm/r" is a compact summary of the idea. It uses the symbols U, G, M, m, r; name what each one stands for before you start. Notice that it contains a ratio, so increasing the denominator makes the result smaller. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Set every slider to its middle value and note the shape of the curve. 2. Move one slider at a time and describe whether the curve shifts, stretches or turns. 3. Find the value where the behaviour changes sharply, then connect it to the formula.
Try this
Start by only moving one slider at a time. Say aloud what you expect, then check.
Common pitfalls
Check units and directions first. Many mistakes come from mixing up a scalar with a vector, or from using a formula outside the conditions where it holds.
How it connects
It builds on “Nearly Circular Orbit”, the topic before it in Physics. Once you are comfortable, continue with “Orbital Period vs Radius”.
Why it matters
Physics explains how the world moves, heats, shines and interacts, and the same principles power technology around you.
Where you might use it
- Revising “Gravitational Potential Energy” before a class, exam or certification
- Designing vehicles, bridges and devices where motion, forces or waves must be predicted
- Understanding how sensors, lasers and communication links actually work
- Explaining everyday phenomena such as sound, light, heat and orbits
Frequently asked questions
What is Gravitational Potential Energy?
Potential energy near a planet is negative and rises toward zero at infinity. It is a beginner topic in Physics.
How do I use the Gravitational Potential Energy simulation?
The panel at the top shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression U = −GMm/r packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Core ideas and first intuitions. No prior knowledge needed. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Nearly Circular Orbit”, the previous topic in Physics. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.