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Do We Get Kicks from Electrostatics?

Consultant Engineer Reg Jones investigates

Did you see us on UK television investigating a most unlikely combination of events: the World Snooker Championships recently held in Sheffield, kicks and electrostatics? Any ordinary snooker player knows that the path followed by the cue or object ball, or both, is often (or always) unexpected. Perhaps the reason is not entirely due to poor play. It seems that top players can also encounter unexpected deflections of the ball, which they term "kicks". Kicks seem to manifest themselves as either marginal deviations of the cue or object ball from the planned direction or more violent lateral or upward movements of either ball after being struck. An electrostatic cause has been suggested, and as a consequence the World Snooker Association contacted colleagues at Kleeneze Sealtech, a manufacturer of anti-static equipment, who in turn asked us to investigate.

The first task was to gather as much information as possible about kicks. This involved attending the Championships and talking to players and referees, all of whom had very definite and mostly conflicting opinions. The consensus on kicks, however, appeared to be:

Kicks very seldom occur

• More kicks have occurred in recent years
• The probability of a kick is greater at the beginning of a frame
• The cause is almost certainly not due to dust or chalk powder on the ball
• Kicks are sometimes associated with less pile on the baize surface
• Kicks are sometimes accompanied by a loud crack

On the face of it, electrostatics seemed to be a possible explanation for the kicks. Modern tournament-standard balls are made of a resin (ARAMITH) which is synthetic and electrically insulating. At the Crucible Theatre, the baize on the Championship tables was meticulously brushed using three different brushes (thus producing charge) before each game. It was also non-conducting and able to hold the charge. The players could acquire charge as they moved around on the thick synthetic carpet. The games were played under dry conditions with heaters under the tables to prevent any moisture from affecting the baize. In addition, our previous laboratory tests filmed for BBC television, in which the cue and object balls were rolled down a baize-lined tube into a Faraday Pail, had showed that both the ball and the baize material readily became charged. The charge was expected to remain on the materials while successive frames were played.

Under the continued scrutiny of the television camera, a practice table was prepared and one of the most well-known of the top players, John Parrott, shot the cue ball several times, covering a range of velocities and spins, in attempts to produce kicks of the cue or object ball. At the same time, I monitored the electrostatic potentials on the balls and on the player himself, using an electric field meter. At one point I asked John not to pot one of the rapidly disappearing object balls so that I could more easily place it in the Faraday Pail. This produced outrage and Scouse humour "You are asking me on television to miss a pot...". Unfortunately, no kicks could be identified by John or the referee, confirming that they are rare events.

When the referee cleaned the cue ball with his cotton gloves, the polarity of the charge on the ball changed from negative to positive. However, all the electrostatic potentials measured on the balls, the baize and John were no greater than 3 kilovolts, small in electrostatic terms. Although no kicks could be studied directly, our subsequent calculations showed that electrostatic charge was unlikely to cause the reported violent deflections of the cue or object ball. It is just possible that a low-velocity shot may be influenced by electrostatic forces due to regions of positive and negative charges on the balls and baize. A particular case is that the nap of the baize may be affected by electric fields arising from the charges, thus producing small, directional resistances to motion.

Every player has his or her own theory regarding kicks. As a recent convert to the game, I believe that a ball may elastically deform momentarily at the point of impact, and that the subsequent reaction against the impacted surface produces the more violent kicks observed. Electrostatics is still a candidate for other types of kicks. We in Wolfson Electrostatics believe that kicks should be identified, reproduced and then examined under test conditions involving top players, electrostatic instrumentation and high-speed photography (to see if my pet theory has any merit). If kicks do have an electrostatic cause, the problem would be solved by using static eliminators to blow neutralising ions onto the table. The question then is: do we want to banish kicks that add controversy to the game and a ready excuse for so many failed shots?

For further information on electrostatic effects contact Wolfson Electrostatics.