Here's why:
* Momentum is a fundamental principle: The law of conservation of momentum is a fundamental principle of physics. It states that the total momentum of a closed system remains constant over time.
* Friction is an internal force: Friction is an internal force within the system of the balls. It acts between the surfaces of the balls and the surface they are moving on. Internal forces do not affect the total momentum of the system.
* Energy is lost, not momentum: While friction does cause energy to be lost (converted into heat), it doesn't "destroy" momentum. The momentum lost by one ball due to friction is transferred to the other ball or to the environment (e.g., the surface they are rolling on).
What you can observe with strong friction:
* Decreasing velocity: You will observe the balls slowing down due to friction. This is because their kinetic energy is being converted into heat.
* Difficult to isolate the system: It might be difficult to truly isolate the system of the balls from their environment, especially if friction is strong. This can make it appear that momentum is not conserved, but the missing momentum is actually transferred to the surrounding environment.
In summary: While friction can significantly impact the motion of objects and make it seem like momentum is not conserved, this is not the case. Momentum is always conserved in a closed system, even with strong friction.
