This is the first of a 4-part series on billiard physics outlining the 4 major contact points: cue stick → cue ball, ball → table, ball → ball, ball → rail.
Spherical balls glancing off each other on a flat surface may sound simple, but there are many physical forces that apply on the pool table. Knowing how and why the balls react the way they do will greatly improve your learning curve by helping you understand why you missed a particular shot or position.
The cue stick striking the cue ball is the first and most important contact point because all motions of the balls on the table depend on it.
Speed vs Accuracy
Higher speeds of the cue stick result in less accurate hits on the cue ball. Slower speeds of the cue stick result in more accurate hits, up to a point.
Tip: Use a range of medium speeds that you are most comfortable with.
Tip: Use a lighter cue stick for more speed and a heavier cue stick for more accuracy.
Hitting the cue ball off-center will cause the cue ball to spin, as long as there is enough friction between the cue tip and the cue ball. There are 4 different types of spin: top (follow), bottom (draw, backspin), left (side), and right (side). These types can be combined to create different actions.
Tip: Chalk your cue tip to increase the friction between the cue tip and the cue ball, allowing for better control of spin and fewer miscues.
Tip: For positioning the cue ball, it is much better to control the speed of the cue ball than to use spin. If you must use spin, it is better to use top or bottom than left or right due to effects in the next sections.
Speed & Offset vs Spin
Higher speeds of the cue stick result in more spin imparted to the cue ball. Greater offsets of the cue stick from center result in more spin imparted to the cue ball. Too much offset without enough friction will cause a miscue.
Tip: Use a high speed with a large offset for maximum spin on the cue ball.
Tip: Aim to hit the cue ball within a half-ball radius to avoid miscues.
Different spin:speed ratios result in different effects on the cue ball.
Tip: Use a combination of speeds and offsets to achieve the desired spin:speed ratio.
When the cue stick hits the cue ball off center, the cue ball will deflect (squirt) in the opposite direction. Deflection changes the angle of your shot and needs to be compensated for. Greater tip offsets and shafts with more mass result in larger deflections.
Note: Some people refer to “deflection” as the cue stick deflecting, which is the opposite of cue ball deflection.
Tip: Get familiar with how your cue stick deflects with various speeds and offsets.