Gravitational Potential Energy
Energy stored by height in a gravitational field: mgh.
About this topic
Gravitational potential energy is the energy stored in an object because of its height in a gravitational field: GPE = mgh. Lifting a 2 kg book 1.5 m gains about 29 J. Only the change in height matters, so you can choose any reference level as zero.
GPE is released as kinetic energy when the object falls, so a ball dropped from height h hits the ground at v = square root of 2gh, independent of its mass. Water stored behind a dam, a raised hammer and a skier at the top of a slope all hold GPE. The path taken to reach a height does not matter, only the vertical change.
Example: a 70 kg hiker climbing 500 m gains about 343,000 J of GPE, which is why hiking is tiring. A roller coaster car on a 40 m hill with 500 kg has 196,000 J that it can convert to speed. Hydroelectric power stations convert GPE of water to electricity.
Misconception: GPE belongs to the object and Earth together, and its zero is arbitrary. Do not use mgh for very large distances where g changes, as in orbit, where a different formula applies.
Key ideas
- Depends on height above a reference
- ΔPE = mgΔh
- Lost as the object falls
Quick check
Use cases: where Gravitational Potential Energy helps
- Homework: review the key idea behind Gravitational Potential Energy before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Gravitational Potential Energy without notes.
- Visual learning: play with the interactive lab to see how Gravitational Potential Energy changes when you adjust its inputs.
- Teaching a friend: explain Gravitational Potential Energy in your own words, then compare your version with the key ideas.
The same laws describe car crashes, sports, satellites and everyday machines.
Frequently asked questions
What is Gravitational Potential Energy?
Energy stored by height in a gravitational field: mgh.
What will I learn in Gravitational Potential Energy?
Depends on height above a reference. ΔPE = mgΔh. Lost as the object falls.
Is Gravitational Potential Energy part of Physics?
Yes. It is one of 150 Physics topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Gravitational Potential Energy lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Gravitational Potential Energy?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.