Momentum And Momentum-Conservation
Momentum describes the movement of a body with a specific mass. For example, a bus driving at a constant speed has a specific momentum. More Examples could be a rolling marble or a jumping ball.
The higher the velocity of a body, the higher its momentum.
The higher a body's mass, the higher its momentum.
Momentum is described by its value and its direction.
The formula used for calculating momentum is the following:
The momentum of a body equals the product of its mass and its velocity.

An important discovery scientists have made is the following:
In a closed system, the sum of all quantities of movement always stays the same. (a closed system means that no outer forces react with the system.) This means for momentum:
In a closed system, the total momentum stays always the same. We call this fact the law of the conservation of momentum.