Conservation of Momentum

Principle that the total momentum of interacting bodies in an isolated system remains constant; the backbone of collision analysis.

Specifications & Metrics

In 1670 John Wallis stated the law of conservation of momentum in his Mechanica sive De Motu, Tractatus Geometricus.
In his 1644 Principles of Philosophy, René Descartes defined 'quantity of motion' as the product of size and speed and claimed it was conserved.
Rocket propulsion relies on it: propellant thrust outward gains momentum while an equal and opposite momentum is imparted to the rocket.