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Originally Posted by Al Skierkiewicz
So Chris,
Your answer brings more thoughts, questions. You are implying that no billiard balls just roll on the surface, they are all slipping? (Until friction with the table surface takes over and rotates the ball.) And no ball can reflect along it's trajectory track since they do not make contact at the percussion point? So the surface must have much more to do with ball interaction than it would seem, correct?
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There is some interaction due to friction between the surfaces of the balls, so that does have an impact. But, if the pool table was frictionless and you hit the cue ball with the cue stick in the dead center of the ball (the motion of the cue stick is parallel to the table), then the ball will only slide - not rotate.
In fact, the friction between two billiards balls would tend to make the target ball spin in the opposite direction of it's motion (think of two gears meshing once the balls contact each other). The friction of the table will impart a force on the target ball causing the ball roll along the surface rather than slip.
So, yes, the table surface has more to do with the motion than the friction between the two balls. Otherwise, english wouldn't be so predictable. The spin of the cue ball would impart side spin on the object ball causing it to curve. As you've probably noticed, the object ball generally goes pretty straight, even with good english on the cue ball. The friction between the balls is pretty negligible compared to the friction between the balls and the felt. I don't know if this is due to coefficient of friction or more due to the very brief contact time between the two balls.