MOMENTUM CONSERVATION

Impulse is force × time, and it equals the change in momentum: J = FΔt = Δp. Stretch the contact time and the force drops in step — the physics of every airbag.

The CM worldline runs straight through the wreck — that line IS momentum.

Δp = 0 while 98.7% of the KE dies — measure a bullet with a protractor.

Δv = vₑ·ln(m₀/m) — every m/s borrowed from the exhaust, and the ln collects.

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

E² − (pc)² = (mc²)², residual zero — and a collision that CREATES mass.

Δλ = λ_C(1−cosθ) — and the recoil electron’s E²−p² is still m², to the bit.

Two 511 keV photons, exactly back-to-back — the 180° derived from p-conservation, residual 0.

λ = h/p: an electron at 100 eV waves at 1.22637 Å — atom-sized, and the microscope is born.