Deflection

One of the effects of english or sidespin on the cue ball is what is called Deflection or Squirt. Basically, the cue ball does not travel the same path that your cue stick is aiming when english is applied to it. Because of the sidespin, the cue ball will tend to slightly travel in the opposite direction of your english. In other words, if you put a left english or left side spin on the cue ball, the cue ball will travel slightly to the right and vice-versa. Refer to illustration below. The white line indicates the path of the cue ball when hit with no english or sidespin, the black line indicates the path of the cue ball when hit with left english. Notice the deflection effect towards the right?.

One thing that makes english difficult is that it is hard to estimate the amount of deflection that you will get on the cue ball. Only with enough experience will you be able to make a good estimate unless you're a genius at math and you can figure it out using your own mathematical formula :-) Anyway, like I said the amount of deflection is dependent on the following:

1. The distance between the cue ball and the object ball. The longer the distance, the more deflection on the cue ball.
2. The amount of spin on the cue ball. Generally, the more spin, the more deflection on the cue ball.
3. The speed of the stroke. Generally, the stronger the stroke, the more deflection on the cue ball.
4. The type of cloth on the table. Again, the issue of friction comes into play. With a rough cloth, more friction therefore more deflection on the cue ball. On a smoother cloth with less friction, the spin on the cue ball does not have as much effect on the cue ball because the cue ball just tends to slide through the cloth.

Please continue to the next article,
Understanding English - Throw