If you triple the distance between two masses, how does gravity change?

F ∝ 1/r² → tripling r reduces F by factor 9.

Why do you not feel gravitational attraction to the person next to you?

G is tiny (10⁻¹¹); typical person masses give force ~ 10⁻⁷ N.

How does surface gravity g relate to Newton's Law?

At Earth's surface: g = GM_Earth/R_Earth².

Pro 🔒~15 min

Gravity Force Lab: Basics

Discover how mass and distance affect gravitational force

How it works

Newton's Law of Universal Gravitation states that every mass attracts every other mass with a force proportional to the product of their masses and inversely proportional to the square of the distance between them. The gravitational constant G = 6.674×10⁻¹¹ N·m²/kg² is extremely small, which is why only planetary-scale masses produce noticeable gravitational forces. This same law describes orbits, tides, and spacecraft trajectories.

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Step-by-step

Drag the masses to adjust their sizes and separation.
The force arrows update in real time.
Use the grid to measure distance.
Compare the force calculated to the formula.
Change both masses to see how F scales.

Key formulas

$F = G\frac{m_1 m_2}{r^2}$ Newton's Law of Universal Gravitation (G = 6.674×10⁻¹¹ N·m²/kg²)

Frequently asked questions

If you triple the distance between two masses, how does gravity change?: F ∝ 1/r² → tripling r reduces F by factor 9.
Why do you not feel gravitational attraction to the person next to you?: G is tiny (10⁻¹¹); typical person masses give force ~ 10⁻⁷ N.
How does surface gravity g relate to Newton's Law?: At Earth's surface: g = GM_Earth/R_Earth².