Gravity Calculator
Calculate gravitational force between two objects, acceleration due to gravity, weight, and orbital velocity using Newton's law of universal gravitation. Perfect for physics students, engineers, and astronomy enthusiasts.
What Is Gravity?
Gravity is a fundamental force of nature that attracts two objects with mass toward each other. According to Newton's law of universal gravitation, every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
This calculator supports four gravity-related calculations:
- Gravitational Force: The attractive force between two objects using F = G × m₁ × m₂ / r².
- Acceleration due to Gravity: The acceleration experienced by an object near a massive body using g = GM / r².
- Weight: The force exerted on a mass by gravity using W = m × g.
- Orbital Velocity: The speed required to maintain a circular orbit using v = √(GM / r).
How Does the Gravity Calculator Work?
The calculator uses Newton's law of universal gravitation and its derived formulas:
Gravitational Constant: G = 6.67430 × 10⁻¹¹ N·m²/kg²
Gravitational Force: F = G × m₁ × m₂ / r²
Acceleration due to Gravity: g = G × M / r²
Weight: W = m × g
Orbital Velocity: v = √(G × M / r)
The calculator includes preset values for Earth, Sun, Moon, Mars, and Jupiter to make astronomy calculations quick and easy. You can also enter custom values for any object.
Why Use This Gravity Calculator?
- Four Modes: Supports gravitational force, acceleration due to gravity, weight, and orbital velocity.
- Preset Values: Quick access to Earth, Sun, Moon, Mars, and Jupiter parameters.
- Unit Flexibility: Switch between SI and Imperial units.
- Visual Chart: Shows how gravitational force changes with distance.
- Free & Private: No registration, no data storage.
❓ Gravity Calculator FAQ
What is Newton's law of universal gravitation?
Newton's law of universal gravitation states that every particle attracts every other particle with a force proportional to the product of their masses and inversely proportional to the square of the distance between them: F = G × m₁ × m₂ / r².
What is the gravitational constant G?
The gravitational constant G = 6.67430 × 10⁻¹¹ N·m²/kg². It is a fundamental physical constant that appears in Newton's law of universal gravitation.
How do I calculate the gravitational force between two objects?
Use the formula F = G × m₁ × m₂ / r². Enter the masses of both objects and the distance between their centers. The calculator does this for you in the "Gravitational Force" mode.
What is the acceleration due to gravity on Earth?
The standard acceleration due to gravity on Earth's surface is approximately 9.81 m/s². This varies slightly depending on altitude and latitude.
How do I calculate the acceleration due to gravity on another planet?
Use the formula g = G × M / r², where M is the planet's mass and r is its radius. The calculator includes presets for Earth, Moon, Mars, and Jupiter.
What is the difference between mass and weight?
Mass is the amount of matter in an object, measured in kilograms. Weight is the force exerted on an object by gravity, measured in newtons. Weight = mass × gravitational acceleration.
How do I calculate my weight on another planet?
Calculate the acceleration due to gravity on that planet using g = GM/r², then multiply your mass by that acceleration: W = m × g. The "Weight" mode of this calculator does this for you.
What is orbital velocity?
Orbital velocity is the speed required for an object to maintain a stable orbit around a central body. For a circular orbit, v = √(GM/r), where M is the central mass and r is the orbital radius.
What is Earth's orbital velocity around the Sun?
Earth's average orbital velocity around the Sun is approximately 29.78 km/s (about 107,000 km/h). This calculator can compute this using the "Orbital Velocity" mode with the Sun's mass and Earth's orbital radius.
What is the gravitational acceleration on the Moon?
The gravitational acceleration on the Moon is about 1.62 m/s², which is approximately 1/6 of Earth's gravity. The calculator includes Moon presets.
What is the gravitational acceleration on Mars?
The gravitational acceleration on Mars is about 3.71 m/s². The calculator includes Mars presets.
What is the gravitational acceleration on Jupiter?
The gravitational acceleration on Jupiter is about 24.79 m/s². The calculator includes Jupiter presets.
How does distance affect gravitational force?
Gravitational force decreases with the square of the distance (inverse square law). Doubling the distance reduces the force to one-quarter of its original value.
What is the difference between Newton's law and Einstein's theory of general relativity?
Newton's law describes gravity as a force between masses. Einstein's general relativity describes gravity as the curvature of spacetime caused by mass. General relativity is more accurate for strong gravitational fields and high speeds.
Can I use this calculator for orbital mechanics problems?
Yes. The "Orbital Velocity" mode calculates the speed needed for a circular orbit. For elliptical orbits, you would need additional calculations not included in this tool.
What units does the calculator use?
You can switch between SI (kg, m, N) and Imperial (lb, ft, lbf) units using the unit system selector. The calculator handles the conversions automatically.