Arguably one of the most important shots in pool is the stop shot. I like to use the word stun to refer to shots where the cue ball is sliding when it contacts the object ball. Stop is what happens when the sliding cue ball hits an object ball full. Fortunately for us, there are many more uses for this sliding cue ball than just straight shots.Before we look at stun shots, we have to understand a little of how the cue ball moves when it is struck on the vertical axis. For now we won’t be looking at what happens when we hit the cue ball off the vertical axis for simplicity.
Hitting the cue ball above the equator causes the cue ball to roll and hitting the cue ball below the equator causes the cue ball to have back spin. Hitting the cue ball exactly in the center causes the cue ball to slide.
But here is the rub. Depending on how low I hit the cue ball or how hard I hit the cue ball, it will have different phases of motion at different distances from where the cue ball started. Whew! That is a lot of words.
Hitting the cue ball low causes it to start out with back spin. When the back spin wears off due to friction with the cloth, the cue ball slides. When the slide wears off, the cue ball starts to roll. Those are the phases of motion.
Now for this article, we want to look at what happens when the cue ball is sliding. We know that when the cue ball is sliding and it hits an object ball full, the cue ball stops. The next bit of information is key for position play. When the cue ball hits an object ball at an angle and is sliding, the cue ball goes down the stun line, which is 90 degrees to the line of centers with the cue ball and the object ball. Here is what that looks like.
As you can see from this diagram, with the cue ball sliding at the moment of impact, it follows a very predictable path 90 degrees to the line of centers between the object ball and the cue ball at the moment of impact.
Wait a minute! Now here is where things get tricky. I can hit the cue ball low and pretty slow and have it sliding, or I can hit the cue ball higher and harder and have it sliding at the moment of impact! What is the right answer?
Well, you can do both, and that is part of the secret of using a stun shot to control not only the direction that the cue ball takes, but also the speed. We will look this in greater detail in other articles.
To start to develop a feel for tip position and speed to get stun shots, set up straight shots and first shoot them with a low and slow stroke, and then with a higher and harder one, each time trying to get the cue ball to stop.
Good luck and see you on the road.