Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I understand the 2 body dynamics very well, but I can't see how the professionals apply their chalked cue and hit the way they do.

As a few for instances:

  1. How much does the chalk come into play in terms of friction?
  2. How off center is it possible to play?
  3. How do they aim the off center?

Also in a situation like this Ronnie O'Sullivan's fantastic play. What useful measurements are there to grade his skill?

share|cite|improve this question
It really helps to just play the game a bit. I seem to recall losing the best part of one term in college to pool. Chalk matters; you can play way off center, but it gets more difficult to control; and practice, practice, practice. – dmckee Jun 27 '12 at 1:40
I'm very familiar with the game. But the way Ronnie does it is like magic to me. Like this – Captain Giraffe Jun 27 '12 at 2:23

The reason for chalking a cue is to increase the friction between the cue and the ball. The increased friction allows the player to impart a spin to the ball by striking it off centre. Without the chalk the tip of the cue would skid over the surface of the ball resulting in a mis-cue.

The chalk is an abrasive. The tip of the cue is leather, and as the cue is used this quickly becomes smooth and slippery. The idea of chalking the tip is to abrade the surface of the leather and make it rougher. The increased roughness of the leather increases the friction between the leather and the ball.

The mechanical analysis of striking a ball off centre is the sort of thing you do routinely in mechanics lectures at university, but the maths can be a little intimidating for non-physicists. This article gives a nice pop science level description of what's going on.

share|cite|improve this answer
Thanks for the answer. I'm not really intimidated by the maths =) Like I stated in the question, the 2-body dynamics, as well as the maths associated with it is simple stuff to me. The under/over cueing can probably be modeled quite accurately with a simple friction model . The thing I am interested in is the side queing. The professionals does not seem that bothered in applying a lot of side to the queue ball. – Captain Giraffe Jun 27 '12 at 20:47
@CaptainGiraffe Sommerfeld treats side queing in his Lectures on Mechanics, if I remember correctly. He certainly treats unver/over cueing. – orbifold Jun 27 '12 at 23:02

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.