Linear Momentum in Physics

Momentum measures how hard something is to stop, and unlike kinetic energy it keeps the direction it was travelling in. That single difference is what makes it so powerful in collisions, because momentum is handed over in a way that can be added up as vectors while the forces involved are too brief and too messy to measure directly. The bridge between those messy forces and the clean answer is impulse, the product of force and time, which turns out to be exactly the change in momentum. The blocks give the quantity itself, the force and impulse relations that change it, and the conservation statement for a system nothing pushes on from outside.