So What Is The Real Rule For Double Hit/Push Shot?
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Dhakala said:My conclusion is not based upon YouTube's video of the shot's action, but upon
- the original positions of the balls, which are shown close-up from multiple angles, and Roger's setup of the tip, which is clearly low-left English. The shot was a shallow cut shot to Roger's left, and the balls were separated by approximately 1/4 to 1/2 inch. (The actual distance is irrelevant; the point is that they were not frozen. )
- my knowledge of physics, which tells me that two objects whose motion is not impeded will move away from each other after collision. The CB's motion was unimpeded because it was not frozen. The tip's motion was unimpeded because Roger did not attempt to impede it; he did not try to force the tip to follow a straight line. Indeed, he facilitated the tip's natural deflection away from the cue ball by lifting his bridge hand up, back, and away in the same direction that the tip was inclined to move. The CB, striking the OB at an angle, moved in the opposite direction, to Roger's right. Tip and CB did not meet twice. Both followed the same paths that they would have followed if the CB started from 1/4 inch or a 1/4 table away from the OB.
I'm sorry, Andrew, but nature does not always conform to our incompletely-informed conjectures. What you choose to believe "must" have happened is not in evidence, and it did not happen.
"It ain't what we don't know that gives us trouble, it's what we know that ain't so." ~ Mark Twain.
BTW, how did you go from "good hit" to "tip must have hit the CB a second time" so quickly? Did Jay show up with a gun?
"Good hit" was referring to the shot in the Beard's story (note I quoted his post). "Tip must have hit the CB a second time" refers to Griffis' shot in the video, which is definitely an unequivocally a foul. Jay's right, and so is Bob Jewett, and so is jsp.
"my knowledge of physics, which tells me that two objects whose motion is not impeded will move away from each other after collision." So which of Newton's laws of motion is this? Is "away from each other" a technical term? I'm not sure I've encountered it in any physics formulae. The relevant physics are the velocity of the 15 after impact, and conservation of momentum and kinetic energy. I'll explain in a little more detail this time.
The 15 went forward almost in a straight line with Griffis' stroke. The CB must also have gone forward in a straight line with Griffis' stroke before contact with the 15, because the CB always goes forward off the cue in close to a straight line with the stroke. Squirt can only make a few degrees' difference at best.
So if the CB's initial direction and the 15's direction after contact are almost the same, then the hit was almost full. When the CB hits an object ball full, it stops. This is conservation of momentum combined with conservation of kinetic energy. The only final CB velocity for which both can be conserved is zero. After it stops, follow/draw/masse can make it start up again. These take time, since the spinning of the ball against the cloth can only accelerate the ball fairly slowly. There's not enough friction to cause sudden change in velocity.
So Griffis' CB almost stopped when it hit the 15. Now, there was a very slight cut being played, so we'll say the CB headed down the tangent line a little after contact. This tangent line is perpendicular to the 15's path, with a slight adjustment because the CB was very slightly airborne. We'll generously guess that the tangent may have been skewed 10 degrees due to this elevation. So we're at maybe 80 degree to the 15's path.
Now, without pause, and with any gradual acceleration, the CB takes off stright toward the rail, at an angle no more than 25 degrees from the 15's path. That's a radical direction change, and there's no available friction with the cloth to cause it (it was airborne at the time), and no hidden magnets or invisible men playing tricks on us. What caused the change in direction? How could the tangent line have been affected this drastically and immediately? Any explanation you might come up with is ludicrous. After the CB left the cue tip and contacted the 15, the cue tip hit it again.
-Andrew
jay helfert said:
I think that if you look on page 44-45 (46/47 PDF pages) of this set of rules from 1914 http://www.sfbilliards.com/rules_1914tpr.pdf you may change your opinion.
For a brief history of the rules of Eight Ball, see my February, 2002 Billiards Digest article at http://www.sfbilliards.com/articles/2002-02.pdf This article has also appeared in the IPT event programs.
Cuebacca said:
All the fouetté shots I've done are extreme left or right with extreme follow or draw.
I suggest getting a copy Billiard Digest (August issue) and reading Mike Shamos' article, it is very interesting. And he does have shot diagrams and very well written explanations.
Another question. A lot of pros make their warm up strokes looking like they are going to draw, then hit with follow. Is it evident that he hit low?
Tracy
Tracy
No. If the shot went as illustrated in the diagram posted by jsp (the forward path), which is pretty much how I saw the video, then the shot was clearly a double hit.Cuebacca said:
Just because you use inside english on a close shot doesn't guarantee you don't foul, as I've demonstrated many times when trying to play a fouette.
It is remarkable how many fairly accomplished pool players (and many referees) don't have even the slightest clue about this stuff.
Bob Jewett said:
I've found over my years of being a TD and Ref, that many 'accomplished' players could care less about rules, "That's why they have TD's and Refs" and what they 'think they know' is only hearsay from other players.
Another problem.. which set of rules is applied? The pros (men and women) have their own set of rules.
I can't speak for all the other refs, but the refs I've been lucky enough to associate with over the years know these situations very well.
I agree Tom. This shot is no foul. It does make a difference on c/b to o/b spacing. Roger's shot is borderline distance between balls. Anyone who knows/shoots these type of shots know's it's only shot very close. At appx 3/8" or better it is destined to be a foul. Then you see the obvious. This shot was not obvious however it was close because of the wider ball spacing.
Up close the ball can be easily drawn several feet. Some are gonna call foul no matter. Most don't know what happens here and all the math/physics solutions is fairly usless. The TD has the final say so your on your own in this territory.
I might add Make Massey does a similar shot caught by TV cameras in the Artistic Pool Chamionships.
Rod
Up close the ball can be easily drawn several feet. Some are gonna call foul no matter. Most don't know what happens here and all the math/physics solutions is fairly usless. The TD has the final say so your on your own in this territory.
I might add Make Massey does a similar shot caught by TV cameras in the Artistic Pool Chamionships.
Rod
Andrew Manning said:
I see now. Thanks for explaining.
Translation: "the 15 moved at a small angle from the line of Griffis' stroke" - a cut shot.
There's that often-mistaken verb, "must," again; see Mark Twain.
Also, why "must" Griffis' CB "have gone forward in a straight line" when every other CB "always goes forward in close to a straight line"?
A few degrees are negligible?
Translation: the hit was not full, but a cut. There is no "almost a cut" or "almost full".
We needn't consider the rest of that paragraph, since we agree that this hit was not full.
Translation: there was an "almost full" shot being played...
I bow to your patently superior expertise in ludicrousness.
Bob Jewett said:
Bob,
I sse no reference here to what happens if the Black ball is made on the break shot. Do you?
What I do know is that there have many variations of the rules for Eight Ball for years. It is and has been played different ways in different parts of the country. The only consistent rule was that if the Eight was made on the break, you win (unless you scratch). This is the way I saw and played Eight Ball for nearly 40 years until the BCA decided it was not a good rule.
How did they play it on the IPT events? I believe the Eight on the break was a win. In past World Eight Ball Championships it was a win also.
If the BCA is going to now say that making the Eight on the break is a luck shot, they must do the same in Nine Ball. It is far easier to make the Nine on the break, as you know.
This is not the first not the last time I will disagree with the powers that be at the BCA. I will say the same thing to any members of the rules committee. It is one stupid rule that absolutely did not need to be changed.
Maybe in 14.1 they will allow a push out after the break shot, in case a player gets tied up. You like that rule? We must take all the luck out of the game, right?
LOL...I totally agree.Bob Jewett said:
I remember a thread a couple months back that asked to define a "banger". I posted that if you cannot tell the difference between a double-hit and a good hit based on the reaction of the CB, then you are probably a banger.
Either there are a lot of bangers out there, or my standards are way too high. For now, I'll just assume the latter.
Dhakala said:He says immediately after repeating his dogmatic opinion in arrogant defiance of pool's two leading rule-making committees and several generations of physicists.
I'm sorry David. i haven't played pool with too many physicists. Where do they hang out? With you I guess.
Has the BCA conveyed its regrets to you?
Actually, YES. I have been asked several times to join various committees.
At this time I am not an active member of the BCA.
A verifiable copy of Eight Ball's original rules would be quite valuable, Jay. May I make an offer on yours?
You can make an offer. Doesn't mean you're gonna get it. Check with Jewett.
Game rules of any kind are neither good nor bad, funny nor solemn. They are arbitrary. One either abides by them or cheats, whether one is a player or a referee.
I like that word...arbitrary. I have a feeling it is your mantra David.
Bob Jewett said:
Bob, I see in the video the cue ball moving forward to strike the OB at a slight angle; the CB rebounding off the OB to Roger's right; and Roger lifting the cue tip well out of the way of any possible double hit.
O, man! This is the first time some of these guys have seen "fouette" spelled correctly! Why do we have to complicate the mundane with the esoteric?
The English did not affect the CB's path to or off of the OB materially, of course. (You taught me that, Bob.) But the cue tip's displacement to the left of CB's center certainly affected the tip's path after impact, throwing it to the left while the CB moved to the right.
So many that it's unremarkable, IMHO.
Dhakala said:Translation: "the 15 moved at a small angle from the line of Griffis' stroke" - a cut shot.
Also, why "must" Griffis' CB "have gone forward in a straight line" when every other CB "always goes forward in close to a straight line"?
A few degrees are negligible?
Translation: the hit was not full, but a cut. There is no "almost a cut" or "almost full".
We needn't consider the rest of that paragraph, since we agree that this hit was not full.
Translation: there was an "almost full" shot being played...
Okay, we're making progress. The more you criticize my wording, the closer I can come to explaining it in a way you'll understand.
So we have an "almost full" hit on the 15. And if you truly think there is no "almost full", then we can take a debate involving billiard balls no further.
And we have an agreement that IF IT WERE totally full, the CB WOULD STOP before friction caused by the ball's spin against the cloth (follow/draw/masse) can accelerate it elsewhere? I assume that you'll agree with this property of full hits, but if you don't then go ahead and argue it in your eagerly awaited rebuttal.
So let's assume a cut angle of 20 degrees. It certainly didn't seem to me to be more than that. Let's use the final direction (immediately after contact with the CB) of the 15 as a frame of reference. Let's call this direction Y (yeah, I'm going Cartesian with this). Now let's imagine a line perpendicular to Y, and call it X.
Now let's dissolve the motion of the balls into vectors in the X and Y directions. If the CB starts out at a 20-degree angle with Y, then let's call its velocity (which has an overal magnitude of 1) .34X + .94Y. This is the entire momentum of the system after the cue has hit the CB but the CB has not yet hit the 15.
So the CB hits the 15 and propels it along direction Y (this was the definition of Y). The magic of conservation of momentum AND kinetic energy means that the 15 will now have a velocity of .94Y + (0)X, and the CB will now have a velocity of .34X + (0)Y. I'll spare you the equations on that.
So we've got a 15-ball that now has 94% of the initial velocity of the CB (which is about right seeing the 15 shoot into the rail in the video), and a CB that retains only 34% of the magnitude of it original velocity, heading off in direction X which points way up table (perpendicular to Y, this was the definition of X).
But we don't observe a CB headed uptable at .34 velocity. We see a CB headed into the rail, in a direction that's closer to Y than it is to X, at something that looks more like .8 velocity. Something hasn't added up.
This time I'll ask YOU what force caused this immediate discrepancy in direction and velocity.
-Andrew
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jay helfert said:
A red herring fished up by a straw man.
As for physicists who play pool, start with Coriolis and look up Ron Shephard.
jay helfert said:
Not the rules committee, I presume.
jay helfert said:
Bob? Does Jay have a verifiable copy of Eight Ball's original rules, written contemporaneously with the game's invention?
jay helfert said:
Yes, I do. If the black is made before a player's group is cleared, he loses. There is nothing mentioned that is special about the break in this matter. Eight on the break loses.
As mentioned in the eight ball history article, it was not until 1971 that making the eight on the break became a win -- it had been a loss before.
While it may be interesting to point out all of the infomal and perhaps even common rules that may or may not have been in effect in the particular pool rooms someone may or may not have visited, that's not a particularly useful way to establish a standard set of rules.
I see it differently, as I have said. While it would have been good to have a slightly different angle for judging the shot -- at a right angle to the path of the 15 -- I think the angle of the cue ball is unambiguously ahead of that perpendicular -- as in jsp's diagram -- and I believe the cue ball was struck below center. I believe the small hop is a red herring.Dhakala said:
Bob Jewett said:
Bob,
I would contend to you that even in the 60's, the Eight on the break was a win. That is the way Eight Ball was played everywhere! In bars and in bar table tournaments. Do you have a rule book from the 60's that says otherwise?
In my lifetime this only began to change, when the BCA instituted their new rule several years ago. Yes, it may be a "rule" now. As far as I'm concerned, a blotch on the record of the rules committee members who thought this one up. Not that they care. I'm not losing any sleep over it either. When I was asked to be on this committee, I replied that I would lobby for a change in this rule among others.
I suspect the reason the Eight on the break is not mentioned in the 1914 rules of Pyramid, is that the players broke safe. So there were no Eights on the break back then. The oral history from that era suggests that in all full rack games, a safe break was employed, similar to the 14.1 break. This includes Rotation, Line up, Pyramid etc.