That's correct! In a closed system, the total momentum before a collision is equal to the total momentum after the collision. This is known as the law of conservation of momentum.

Here's why:

* Closed system: A closed system is isolated from external forces. This means no force from outside the system can influence the objects within it.

* Momentum: Momentum is a measure of an object's mass and velocity. It's calculated by multiplying the object's mass by its velocity.

* Conservation: The law of conservation of momentum states that in a closed system, the total momentum remains constant. This means that the total momentum of all the objects in the system before the collision will be the same as the total momentum of all the objects in the system after the collision.

Example:

Imagine two billiard balls colliding on a frictionless table. The system is closed because no external forces are acting on the balls. The total momentum of the two balls before the collision (mass * velocity) is equal to the total momentum of the two balls after the collision.

Important Note: While the total momentum remains constant, the momentum of each individual object might change during the collision.