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:I'm sitting here wondering how knowing any of this might improve my game and, as of now, I'm drawing a blank here. Regardless of "why" I think the cue ball rolls forward after contacting another ball, it's still going to do just that if I hit the cue ball high.
I don't agree with the "simplicity by omission" approach, but I'm unable to see a practical application of this knowledge. I'm not saying that one doesn't exist. I'm just saying that I'm unable to see it.
Proven by Physics that it does curve. Those who said it didn't curve per se' were confused at the physics.Fragged said:They said curve balls didnt curve not too long ago also. Im sticking to my guns.
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: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.
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:... Does anyone know of a set of experiments like that that have already been conducted?
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 sitting here wondering how knowing any of this might improve my game and, as of now, I'm drawing a blank here. Regardless of "why" I think the cue ball rolls forward after contacting another ball, it's still going to do just that if I hit the cue ball high.
I don't agree with the "simplicity by omission" approach, but I'm unable to see a practical application of this knowledge. I'm not saying that one doesn't exist. I'm just saying that I'm unable to see it.
worriedbeef said: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.
Johnnyz86 said: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).![]()
Bob Jewett said: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.
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.)
Tom Simpson:
I've pretty much been off the forums for about 10 years now.
Bob Jewett said: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.
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.)