🌀 Gyroscope Precession
A fast-spinning gyroscope doesn't fall — it precesses. Gravity's torque τ = r×mg rotates the angular momentum vector, making the spin axis sweep a cone at rate Ω = mgr / (I·ω). Slow the spin and watch precession speed up.
🔭 Physics of Precession
When gravity pulls the gyroscope's centre of mass downward, it exerts a horizontal torque τ = r × F perpendicular to both the spin axis and vertical. Instead of falling, angular momentum changes direction: dL/dt = τ, so the spin axis sweeps a cone — a phenomenon called steady precession.
Key insight: precession rate Ω is inversely proportional to spin ω — a slower gyroscope precesses faster. This is why well-thrown tops stay upright, and explains the 26,000-year wobble of Earth's axis.