The Miff of Topspin (Simpson chimes in)
- Thread starter Tom Simpson
- Start date
Here's one useful result: because of the efficiency of the conversion of follow into roll, if you have a rolling cue ball and it strikes an object ball full, the cue ball will roll forward 1/6th of the distance the object ball travels (rail bounces not included). If you're shooting with the cue ball on the head rail and object ball is on the head string and straight into a pocket, the object ball will go six diamonds and the cue ball has to roll forward at least a diamond if you let it roll. Alternatively, for every diamond you drive the object ball on a nearly full shot, the cue ball has to roll forward at least a ball unless you use draw/stop/stun.Jimmy M. said:
A more advanced related shot from one pocket is when you are shooting a long bank of an object ball that's between the side pockets. If the shot is nearly straight, and you play pocket speed with follow, the cue ball will end frozen to the head rail. If the object ball is not between the side pockets, you can estimate where it will end up or how you have to adjust your object ball speed to make the cue ball right. (A small detail: if the cue ball is light or heavy, or you have a bad head cushion, the "magic" spot for the object ball will be different.)
Last edited:
tom is right and it's pretty simple if you think about it.
basically there is no such thing as overspin. where the cue ball is spinning more than it's rolling. (think of a car's two rear wheels stuck in some mud - spinning more than they're gripping)
if you hit a very hard top spin shot, the cue ball will hop on impact, and while it is in mid air for a split second is the only time it will be spinning faster - as soon as the ball lands back on the cloth it'll grip straight away and accelerate forward. and as it's going forward it's rolling. rolling very fast yes, but not overspinning. the ball is fully gripped to the cloth at all times.
basically there is no such thing as overspin. where the cue ball is spinning more than it's rolling. (think of a car's two rear wheels stuck in some mud - spinning more than they're gripping)
if you hit a very hard top spin shot, the cue ball will hop on impact, and while it is in mid air for a split second is the only time it will be spinning faster - as soon as the ball lands back on the cloth it'll grip straight away and accelerate forward. and as it's going forward it's rolling. rolling very fast yes, but not overspinning. the ball is fully gripped to the cloth at all times.
I'm intrigued by the whole discussion.
This is pure speculation, but I suspect that a lot of people (myself included) underestimate the amount of distance that a cueball travels before it attains natural roll in every case except for immediate natural roll. There are obviously an awful lot of variables that affect that timing, but I'd find it really interesting to see some examples or tests that show just how far that distance is.
I'd suspect that at certain speeds and tip/ball contact points, the test would either need to be conducted on a surface longer than a 9' table provides, or calculated out based on the results obtained from the 9' table.
Does anyone know of a set of experiments like that that have already been conducted?
This is pure speculation, but I suspect that a lot of people (myself included) underestimate the amount of distance that a cueball travels before it attains natural roll in every case except for immediate natural roll. There are obviously an awful lot of variables that affect that timing, but I'd find it really interesting to see some examples or tests that show just how far that distance is.
I'd suspect that at certain speeds and tip/ball contact points, the test would either need to be conducted on a surface longer than a 9' table provides, or calculated out based on the results obtained from the 9' table.
Does anyone know of a set of experiments like that that have already been conducted?
That's not my understanding of the situation. If you do manage to get excess top spin, it will take some time and distance to wear off. Whether this happens completely on the first landing after the initial hop depends on a lot of things. I suspect that under some reasonable conditions, the ball leaves the table from the first hop still with excess forward spin. Do you have a reason to believe otherwise?worriedbeef said:
I believe that the coefficient of friction between the ball and cloth has already been measured at around 0.2 (with variations for new cloth, wax, humidity, etc.). That information is sufficient for a physicist to calculate how long a particular ball will take to achieve natural roll. The easiest practical way to test for smooth rolling is to look at the half-ball angle at different distances. The reason to look at the half-ball angle is explained by Dr. Dave's articles and in Byrne's Advanced book and in several articles I wrote for On The Break News and Billiards Digest.spoons said:
Unlike lots of theoretical stuff, understanding smooth rolling is actually important to playing well. Whether you need to understand it consciously is another question.
Tom, good that you chimed in because, however innocently, the OP in the other thread badly mischaracterized what you wrote...at least if this post conforms to your article which I haven't read yet.
Here, you say there CAN be slight overspin imparted by the cue tip.. Right... and that the effective overspin occurs when the cb re-accelerates after impact...Right again.
And you say that knowing that isn't key to successfully executing force follow shots...Right again...but that it's interesting to know...Right Again.
Too bad the topic got off on such a bad footing. Welcome back to the forum.
Regards,
Jim
PS: And to the train wheels moving in the opposite direction of the train advocates...does that mean that all passangers have to buy a round trip ticket?????
(-:
Here, you say there CAN be slight overspin imparted by the cue tip.. Right... and that the effective overspin occurs when the cb re-accelerates after impact...Right again.
And you say that knowing that isn't key to successfully executing force follow shots...Right again...but that it's interesting to know...Right Again.
Too bad the topic got off on such a bad footing. Welcome back to the forum.
Regards,
Jim
PS: And to the train wheels moving in the opposite direction of the train advocates...does that mean that all passangers have to buy a round trip ticket?????
(-:
Tom Simpson said:Hi Everyone,
I've pretty much been off the forums for about 10 years now. Someone gave me a heads up about the Myth of Top Spin?? thread that's underway, so I thought I should visit and read it.
I'm now more convinced than ever that this myth needs to be cleared up. My next column (September issue) will address this in a little more depth. A lot of players have a mistaken idea of how follow works, and it's related to this issue.
For those who don't get Inside Pool, I've attached a pdf of the original article, so you can see what the fuss is about.
I think poster 3andstop did a nice job in post #34. Thanks to you and the various other physics fans for helping.
What I feel is really going on is that our adoption of the term "topspin" has led most players to a mistaken idea of how balls behave. It's easy to see how players assume that hitting above center causes overspin. Before I started reading pool physics, I thought so too. I can also see how playing with that mistaken notion can still produce terrific results. I believe that the clearer your grasp of this stuff, the better and smarter you will play. Just as you can learn to pocket balls perfectly without knowing anything about throw, you can play perfect follow without understanding how follow actually works. But I think the truth helps us learn more quickly and helps us better solve new game situations.
My experience is that most players have trouble at first believing that what they've always assumed was overspin in the CB is nothing more than roll - and that "force follow" is merely fast roll. As we hit higher above center, the skidding of the CB decays to full natural roll sooner in the shot. As we hit harder, the skidding zone lengthens.
Other than the special cases of masse and the fleeting overspin it's possible to get, hitting in the last 1/8" of CB before the miscue boundary, what we refer to as "topspin" is roll. Overspin is what you see in the CB after a collision has removed some or all of its linear force. What was, prior to the collision, a rolling CB, now is a stopped or slower moving CB with overspin. That overspin was not there when the CB left the tip.
Please consider that maybe the physics guys are correct (and maybe I'm not nuts).
Jimmy M. said:
I'm with you, Jimmy. As an instructor, the responsibility of learning pool physics lies with me, not my students. And then it is my job to explain those physics in the simplest manner that each individual student will be able to comprehend; not make them more complicated than they need to be. Over complicating things seldom helps players play better, faster.
As evidence of this, Jimmy, please allow me to offer the following: No offense, but I truly believe that my knowledge of pool physics is greater than yours. I believe it always has been, and probably always will be. However, you're a better player than I. You always have been, and probably always will be.
Now, do you think a physicist could explain that?
Roger
One time I asked Efren why he hasn't written a book on his shot-making. He smiled at me and protested, "how can I describe the way I hit the ball when the only time I know that I made the right shot is from the sound of the cuetip's impact on the cue ball."
He said that before he makes the shot, he "talks" to his arm, cue and to the balls ordering his arm to produce a stroke that produces an intended impact sound that will be obeyed by all the balls in action!
Greek to everyone just like the way things are with non-physicists. How's that for more confusion!
Actually, he makes sense. The sound of the cuetip's impact tells him if there should be friction against the cloth, collision against the slate, etc. - or mere cuetip-cueball collision. But he is lucky because he gets by without all these physics stuff and he understands all the hows. I don't think he cares about the whys, and he never had the luxiary of billiard academies. His little computer speaks in binary while all the rest is in user-friendly interface.
He said that before he makes the shot, he "talks" to his arm, cue and to the balls ordering his arm to produce a stroke that produces an intended impact sound that will be obeyed by all the balls in action!
Greek to everyone just like the way things are with non-physicists. How's that for more confusion!
Actually, he makes sense. The sound of the cuetip's impact tells him if there should be friction against the cloth, collision against the slate, etc. - or mere cuetip-cueball collision. But he is lucky because he gets by without all these physics stuff and he understands all the hows. I don't think he cares about the whys, and he never had the luxiary of billiard academies. His little computer speaks in binary while all the rest is in user-friendly interface.
worriedbeef said:
why do you use the car's analogy then? cars certainly overspin - when stuck in mud or when driving and too much torque is applied to the wheels even in straight lines.
its certainly possible for overspin.. take a ball, spin it with your hands forward as well as throwing it sligtly forward. it will start off slower and then accelerate with the overspin.
granted some of the time the ball will not be touching the cloth, as you hit it above center it will push the ball down which bounces it up, the more you bounce it, the more spin is lost after the collision in the air.
Tom Simpson said:Hi Everyone,
I've pretty much been off the forums for about 10 years now. Someone gave me a heads up about the Myth of Top Spin?? thread that's underway, so I thought I should visit and read it.
I'm now more convinced than ever that this myth needs to be cleared up. My next column (September issue) will address this in a little more depth. A lot of players have a mistaken idea of how follow works, and it's related to this issue.
For those who don't get Inside Pool, I've attached a pdf of the original article, so you can see what the fuss is about.
I think poster 3andstop did a nice job in post #34. Thanks to you and the various other physics fans for helping.
What I feel is really going on is that our adoption of the term "topspin" has led most players to a mistaken idea of how balls behave. It's easy to see how players assume that hitting above center causes overspin. Before I started reading pool physics, I thought so too. I can also see how playing with that mistaken notion can still produce terrific results. I believe that the clearer your grasp of this stuff, the better and smarter you will play. Just as you can learn to pocket balls perfectly without knowing anything about throw, you can play perfect follow without understanding how follow actually works. But I think the truth helps us learn more quickly and helps us better solve new game situations.
My experience is that most players have trouble at first believing that what they've always assumed was overspin in the CB is nothing more than roll - and that "force follow" is merely fast roll. As we hit higher above center, the skidding of the CB decays to full natural roll sooner in the shot. As we hit harder, the skidding zone lengthens.
Other than the special cases of masse and the fleeting overspin it's possible to get, hitting in the last 1/8" of CB before the miscue boundary, what we refer to as "topspin" is roll. Overspin is what you see in the CB after a collision has removed some or all of its linear force. What was, prior to the collision, a rolling CB, now is a stopped or slower moving CB with overspin. That overspin was not there when the CB left the tip.
Please consider that maybe the physics guys are correct (and maybe I'm not nuts).
Thank you for working harder on this point than you thought you would.
Thanks for posting Tom. I've read this little fact many years ago from various sources, and IMO it does help to know how it works - why try to strike the cue ball at the very top of the miscue limit when doing so will not generate any more appreciable (if any) follow? I know this misinformation has been out there for a long time, as I just got into a "discussion" with a fairly decent player about this very topic at a recent pool school. Just because something doesn't make sense, or is not what you thought it was all these years, does not make it wrong...
Thanks again, glad to see you posting here!
Scott
Thanks again, glad to see you posting here!
Scott
Bob Jewett said:
These are gems, Bob. Thanks.
People with migraines will still learn these shots, but it'll take more trial and error and won't translate as easily for each new shot. That's the value of this stuff.
pj
chgo
I can sympathize, but we need you, man - we're outnumbered!
pj
chgo
