- Pool balls are moving on the surface of the felt of the pool table
- A pool table is a kind of object
- A pool ball is a kind of object
- Friction occurs when two object 's surfaces move against each other
- Therefore, friction will occur between the pool ball and the felt of the pool table

- Friction will occur between the pool ball and the felt of the pool table
- Friction causes the speed of an object to decrease
- A pool ball is a kind of object
- Therefore, friction will cause the speed of the pool balls to decrease

Hence, friction will cause the speed of the pool balls to decrease
Q: Two pool (billiard) balls collide, causing each to move in a different direction. Eventually, both come to a stop. The most important factor in causing them to stop is
Context:
- Friction causes the speed of an object to decrease 
- Pool balls are moving on the surface of the felt of the pool table 
- A pool table is a kind of object 
- A pool ball is a kind of object 
- Friction occurs when two object 's surfaces move against each other