What Is Gravitational Potential Energy?
Gravitational potential energy (PE) is the energy stored in an object due to its position above a reference point in a gravitational field. When released, this stored energy converts to kinetic energy as the object falls. PE is one of the two components of mechanical energy.
Potential Energy Formula: PE = mgh
Where m is mass (kg), g is gravitational acceleration (m/s²), and h is height above the reference point (m). The result is in joules. This formula is valid near the surface of a planet where g is approximately constant.
Gravity on Different Worlds
| World | g (m/s²) | Relative to Earth |
|---|---|---|
| Earth | 9.807 | 1.00× |
| Moon | 1.62 | 0.17× |
| Mars | 3.71 | 0.38× |
| Jupiter | 24.79 | 2.53× |
The Reference Point
PE is always relative. You can choose any height as zero. What matters in physics problems is the change in PE (ΔPE = mgΔh). Negative PE simply means the object is below the reference point.
How to Use the Calculator
- Choose what to calculate: PE, mass, height, gravity, or compare worlds.
- Enter values. Change gravity for non-Earth calculations.
- Click Calculate.
- Review the result, formula substitution, and interpretation.
Example Calculations
10 kg, 5 m, Earth
PE = 10 × 9.807 × 5 = 490.3 J
70 kg, 10 m, Moon
PE = 70 × 1.62 × 10 = 1 134 J
PE = 980 J, m = 10 kg → h (Earth)
h = 980 / (10 × 9.807) = 9.997 m
Common Mistakes
- Using cm without converting to metres.
- Forgetting to specify the reference height.
- Using weight (in Newtons) instead of mass (in kg).
- Using Earth's gravity for a different planet.
- Applying PE = mgh at very high altitudes where g varies.
Accuracy and Limitations
PE = mgh is an approximation valid near a planet's surface where gravitational acceleration is approximately constant. For large heights (comparable to the planet's radius), the general formula PE = −GMm/r is needed. This calculator does not account for general relativity, atmospheric buoyancy, or non-uniform gravity fields. It is educational and should not replace professional engineering calculations.
FAQ
What is gravitational potential energy?›
It is the energy stored due to an object’s position in a gravitational field. PE = mgh near a planet’s surface.
Can potential energy be negative?›
Yes. PE is relative to a reference point. If the object is below that point, h is negative and PE is negative.
Why does gravity differ on other planets?›
Surface gravity depends on the planet’s mass and radius. Larger and denser planets have stronger gravity.
Does PE = mgh work at very high altitudes?›
Only approximately. For large heights (compared to the planet’s radius), the general formula PE = −GMm/r is needed.
What unit is PE in?›
The SI unit is the joule (J). 1 J = 1 kg·m²/s².
How does PE relate to KE?›
When an object falls, PE converts to KE. At the bottom (ignoring friction), all PE becomes KE: ½mv² = mgh.
What is the standard gravity value?›
g = 9.80665 m/s² (standard gravity). Actual surface values vary slightly by latitude and altitude.
Sources
Author & technical reviewer
Manish Kumar
PhysicsCalcs tools are reviewed with an educational focus: clear formulas, transparent assumptions, and practical context for students and science learners.
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