In this section we're going to discuss two physical laws that give us some mathematical relationships that help determine the resultant velocities of two collided objects. But before discussing the laws of conservation of momentum and conservation of energy, we of course need to introduce the concepts of momentum and energy.
Momentum is a quantity associated with all objects and characterized by an object's mass and velocity. Momentum is a vector whose direction is given by the velocity. Mathematically, this is momentum: