Let's talk cue-ball physics. This episode: Object-ball

Object-ball 

--- The object-ball is the ball being hit by the cue-ball. If the cue-ball hits the object-ball full in the face, it will travel straight forward if no side spin is applied to the cue-ball. When it is hit by the cue-ball with side spin at slow speed, it will slightly nudge to the left or right. If hit with backspin or topspin, it will affect the forward motion of the object-ball. For example, if hit by the cue-ball with screw, the forward motion will increase, allowing it to move forward after making contact with another ball. When the object-ball is hit at a large angle, it will move sideways and be nudged off line in the direction of the cue-ball's travel. The newer the balls, the less this will occur. There is no need to mention that if one wants to pot the object-ball, it needs to be hit/aimed correctly. The object-ball is the ball that must be potted to commence or to keep a break going, so the state of this ball is very important. A dirty ball will rattle in the pocket more easily, as it will grip on the cushion cloth, resulting in a missed pot. This is especially true along the cushion rail. Shiny, slippery clean balls will not grip the cushion cloth and will slide more easily into the pocket. Additionally, the distance the object-ball travels will decrease when playing with dirty and dull balls. A clean object-ball will travel further because of the initial slide after impact by the cue-ball, and when playing a split, the balls will open more easily. However, because the balls are so clean—particularly when playing with a new set of balls—when they hit the cushion, they will start to slide out of the cushions, resulting in loss of ball run. Therefore, with a new set of balls, you will need to hit into the cushions a little harder to achieve the desired position.