A stop shot works for one reason only: the cue ball is still sliding when it arrives. Hit the white dead centre with a level cue, firmly enough that it has not yet started to roll, and take the object ball dead full — the speed transfers across and the cue ball stays put. Every stop shot that fails at distance fails for the same reason. The white had already stopped skidding and started rolling, and a rolling ball wants to keep going.
01
The cue ball has two lives on every shot
When your tip strikes the centre of the cue ball, it does not set the ball spinning. It pushes the whole ball forward. For the first stretch of its journey the cue ball is therefore skidding across the cloth like a hockey puck, its underside dragging rather than gripping.
That drag is doing something. Friction at the contact patch pulls back on the bottom of the ball, spinning it up a little more with every inch travelled while it slows the ball down. Sooner or later the two meet: the surface of the ball is turning backwards exactly as fast as the ball is travelling forwards, and from that moment it rolls instead of slides. Pool players call this natural roll.
Nearly everything confusing about cue-ball behaviour comes from not knowing which of those two states the white was in when it arrived.
02
The one number worth remembering
A cue ball struck in the centre takes up natural roll when it has lost about 29 per cent of its speed — it is rolling once it is down to roughly five-sevenths of the pace it left your tip with. That figure does not change with the cloth, the ball, or how hard you hit it. Only the distance it takes to get there changes.
This is also why cue-ball speed feels unpredictable. The sliding phase burns pace quickly, because sliding friction is brutal; the rolling phase burns it very slowly, because a rolling ball meets almost no resistance on cloth. So the white sheds a third of its speed early and then coasts, sometimes for six or eight feet, on what is left. Small differences in your stroke show up as large differences in where it settles.
Slide length grows with the square of the speed. A soft centre-ball shot is rolling within a foot or so, a medium one inside a couple of diamonds, and a hard one can still be sliding as it reaches the far end of the table. Fresh, fast cloth stretches all of those numbers.
03
A stop shot is a timing problem, not a stroke
Most players are taught the stop shot as a technique: hit the centre, hit it firmly, keep the cue level. That works — over about two feet. It quietly assumes the object ball is close enough that the slide has not run out.
Reframe it and the shot works at any distance. Your job is to arrange for the cue ball to arrive with no spin on it. Close up, centre and firm does that by itself. Further away, a centre hit will be rolling long before it arrives, so give it a small amount of backspin and let the cloth eat exactly that much on the way: a tip below centre for a mid-range stop, a little lower and softer again for a long one.
You now have a self-diagnosing shot. If the cue ball creeps forward after contact, it had taken up roll early — hit lower next time. If it draws back, your backspin outlived the journey — hit slightly higher or slightly softer. The feedback tells you precisely what to change, which is why the stop shot is the best single drill in pool.
04
The same shot on a cut: the tangent line
Stun is the state; stop is only what it looks like on a full hit. Cut the object ball instead and a stunned cue ball does something far more useful. It leaves along the tangent line — the line at right angles to the path the object ball takes — and it holds that line, because it has no spin to bend it either way.
That predictability is the whole point. A rolling cue ball, by contrast, keeps its topspin through the collision and curves forward off the tangent line; on cuts between roughly a quarter-ball and a three-quarter-ball hit it ends up around thirty degrees from its original path, which is the familiar 30-degree rule. A cue ball with live backspin bends the other way and comes back.
So the tangent line is not one of three options; it is the line all three start on. Stun stays on it, follow curves forward off it, draw pulls back off it. See it on every shot and position play becomes a question of how far off that line to bend, rather than a guess.
05
Using the slide on purpose: the drag shot
There is a second, quieter use for all this. Slow rolling shots are unreliable: a gently rolling cue ball is at the mercy of every imperfection in the cloth, and on a table that is not quite level it drifts off line.
The drag shot fixes that. Strike below centre with a firmer stroke than the distance seems to need. The white sets off quickly with backspin, the backspin dies, and it settles into true natural roll for the rest of the trip — arriving softly, but having spent most of the journey moving fast enough to ignore the cloth. It is the standard way to play a delicate long shot without letting the table interfere.
A stop shot uses backspin that runs out exactly at the object ball. A drag shot uses backspin that runs out well before it. Same stroke, different timing, opposite goals.
06
What lengthens and shortens the slide
Speed. By far the biggest factor, and not proportional: doubling the pace roughly quadruples the sliding distance. That is why a hard shot behaves differently rather than simply travelling further.
Cloth. Fast, well-brushed worsted grips less and lets the ball slide further; old, napped, or dusty bar-table cloth grabs it and puts it into roll early. This is a real part of why the same shot plays differently on an unfamiliar table.
Tip height. Above centre skips the sliding phase almost entirely, because you handed the ball its rolling spin at the start. Below centre lengthens it, since the cloth must kill the backspin before it can build forward roll.
Cue elevation. Raising the butt drives force down into the cloth instead of forward. It shortens the useful slide, kills draw quickly, and is the most common reason a stop shot creeps.
07
Sliding is not skidding, despite the word
Pool uses “skid” for two unrelated things and it trips people up. Everything above describes sliding: normal, predictable, useful physics that every struck cue ball goes through.
The other skid — also called cling or kick — is a bad contact between two balls. Chalk dust or moisture briefly raises the friction at impact, the object ball is thrown off its line, and the sound is a dull click instead of a clean knock. You cannot plan for it or correct it mid-shot. Clean balls make it rarer; nothing makes it impossible.
08
How to feel where the slide ends
Set up a straight shot with the object ball two feet away and play centre-ball stop shots until the white dies every time. Then move the object ball back six inches and repeat. At some point the cue ball starts following through, and that distance — on that table, at that pace — is where your slide runs out. Knowing that one number for the table you play on beats any amount of theory.
The experiment only teaches you something if the same stroke produces the same result, so a simulator with deterministic physics is a useful place to run it — Duel steps its physics at a fixed rate for exactly that reason. On a real table, brush the cloth and accept a little noise.
09
Common questions
How do you do a stop shot in pool?
Hit the cue ball dead centre with a level cue, firmly enough that it is still sliding rather than rolling when it reaches the object ball, and take the contact dead full. A sliding cue ball has no forward spin to carry it, so a full hit hands the speed to the object ball and the white stops where it stood. Over longer distances add a touch of draw, so that the backspin decays to nothing exactly as it arrives.
Why does the cue ball slide before it rolls?
A centre-ball hit sends the cue ball forward without spinning it, so for the first part of its journey the ball is skidding across the cloth rather than rolling on it. Friction between ball and cloth drags at the bottom of the ball and spins it up until the surface speed matches the travel speed, which is the point it starts to roll naturally. That transition happens once the ball has lost about a third of its original speed.
How far does a cue ball slide before it starts rolling?
Mostly on how hard you hit it, because the slide grows with the square of the speed. A soft centre-ball shot is rolling within a foot or two, a medium one inside a couple of diamonds, and a hard one can still be sliding at the far cushion. Fast, freshly brushed cloth stretches the slide; dusty cloth shortens it.
What is the difference between a stun shot and a stop shot?
Stun describes the state of the cue ball at contact — travelling forward with no spin on it — and a stop shot is what that state produces on a dead-full hit. On a cut shot the same stunned cue ball does not stop; it runs off along the tangent line, at right angles to the direction the object ball takes. Stop and stun are the same shot meeting two different angles.
Why does my stop shot work close up but not from distance?
Because the cue ball has stopped sliding by the time it gets there. Over a long distance a centre-ball hit takes up natural roll early in the journey and arrives with topspin, which carries it forward through the object ball instead of killing it. The fix is a low centre hit that puts on just enough backspin to be worn away to nothing at the moment of contact.
Is skid the same thing as the cue ball sliding?
No, and the shared word causes real confusion. Sliding is the normal physics of every struck cue ball before it takes up roll. Skid — also called cling or kick — is a bad contact between two balls, usually caused by chalk or dust, that throws the object ball off line with a dull click. Sliding you can use on purpose; skid is bad luck.