ROTATION

a = g·sinθ/(1+β) — shape alone runs the race. Mass and radius cancel, bitwise.

τ = Iα, θ = ½αt², KE = τθ — F = ma in a spinning alphabet, audited to 1e-12.

Gravity turns the computed angular-momentum vector: full Euler–quaternion motion, exact regular precession, nutation, and an honestly bounded fast-top estimate.

Pull in: I₁ω₁ = I₂ω₂ holds, KE jumps. L conserved, energy not — two different books.

A point on a rolling wheel traces a cycloid — contact stops dead, the top races at 2v, the flange runs backward.

A toppling chimney rotates, so its tip accelerates at (3/2)g·sinθ — past 42° that beats free fall, and the mortar tears at L/3 up.

Match the periods from two pivots and g = 4π²L/T² — the moment of inertia cancels completely. Kater weighed gravity without knowing I.