Conservation of momentum

The conservation of momentum simply states that:

The total momentum of a closed system stays the same, even after a collision.

What does this mean?

When multiple objects collide, the momentum of each object may change, but the total momentum of all the objects combined will remain the same.

Vectors

Remember that momentum is a vector quantity.

If two objects are moving in opposite directions, towards each other, then collide, their momentums before the collision may be, for example:

• Object A:
• Object B:

The total momentum before the collision is:

So the momentum of the two objects after the collision must also add up to , even if the momentum of each individual object changes.