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Cavendish Torsion Balance — Measuring Newton's G

Recreate Henry Cavendish's 1798 torsion-balance experiment in 3D: two small spheres on a suspended arm are pulled by large lead spheres, twisting a fiber against its own restoring torque. Read the equilibrium angle off an amplified optical-lever spot and back out the gravitational constant G.

Physics & Mechanics3DModerate60 FPS📱 Mobile-adapted

In 1798 Henry Cavendish used a torsion balance to make the first laboratory measurement of the gravitational constant — effectively "weighing the Earth." This simulation rebuilds the apparatus in 3D: a suspended dumbbell of two small lead spheres is drawn toward two large lead spheres placed at opposite corners, twisting the fiber until its restoring torque balances gravity's pull. Adjust the large-sphere mass and fiber stiffness, watch the amplified optical-lever spot sweep across the scale, and read a live estimate of G computed straight from the equilibrium twist angle.

⚙ Under the hood

Recreate Henry Cavendish's 1798 torsion-balance experiment in 3D: gravity from two large lead spheres twists a suspended fiber against its own restoring torque, and an amplified optical-lever spot lets you read off the equilibrium angle and infer the gravitational constant G.

history of sciencegravitytorsion balanceCavendish experimentclassical mechanics

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install