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1hit1der
02-05-2007, 12:42 PM
Interesting discussion brewing on AZ:

Thought I'd post this for those that enjoy the physics and math behind the game.

cushioncrawler
02-06-2007, 09:16 PM
I agree with the statement that a 1mm gap leaves the qball about 10dg clear for the jump, which duznt look quite enuff to do what he duz. But, if the qball squirts away say 1mm during the first half of the downstroke, ie while being crushed into the bedcloth, the gap bekumz 2mm, which gives say 20dg, which would explain the rezult.

The comments about a cue-foul helping the rezult are bullkrap, any such foul (here) would send the qball away from the target, not help.

If there is some sort of cushion contact, by the qball, as suggested, then this makes everything different. But i reckon that if u wanted the cushion to help the jump angle, then u would havta hit the qball on the far side from the jump, ie on the outside, not the inside, and he is obviously hitting inside.

Why would u want to play a very difficult (impossible) jump shot when a "direct" simple masse is much eezyr, what with the object ball being in the lips of the pocket, and a 1 or 2 rail double iz allmost allwayz an option and is eezyr allso. madMac.

SpiderMan
02-07-2007, 09:24 AM
<blockquote><font class="small">Quote 1hit1der:</font><hr> Interesting discussion brewing on AZ:

Thought I'd post this for those that enjoy the physics and math behind the game. <hr /></blockquote>

I'm with Eric in calling it a foul. The CB "flight path" must be parabolic if there is no additional influence, such as hitting the cue shaft. If the CB never gains enough height to justify a parabolic path that would clear the OB, look for the foul.

SpiderMan

dr_dave
02-07-2007, 09:44 AM
<blockquote><font class="small">Quote SpiderMan:</font><hr> <blockquote><font class="small">Quote 1hit1der:</font><hr> Interesting discussion brewing on AZ:

Thought I'd post this for those that enjoy the physics and math behind the game. <hr /></blockquote>

I'm with Eric in calling it a foul. The CB "flight path" must be parabolic if there is no additional influence, such as hitting the cue shaft. If the CB never gains enough height to justify a parabolic path that would clear the OB, look for the foul.<hr /></blockquote>I think this is similar to our miscue foul debate. Strictly, under high-speed video scrutiny, highly elevated jump shots (and some masse shots) are fouls. However, to me, the important question is whether it would or could actually be called a foul in league or tournament play.

I think there are several examples of shots that are technically fouls (see the links under "fouls" in the threads summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html)), but they are not called as fouls in leagues or tournaments, even with experienced referees. Regardless, when rules are re-written, these cases should be taken into consideration to eliminate the uncertainty. For example, with the miscue example (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=241789&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;vc=1) we debated previously, maybe the rules could explicitly state: "An unintentional miscue is not by itself a foul, even if the ferule or shaft makes secondary contact with the cue ball." This would avoid the whole debate and make the rules less open to interpretation.

Regards,
Dave

1hit1der
02-07-2007, 01:32 PM
<blockquote><font class="small">Quote cushioncrawler:</font><hr>
The comments about a cue-foul helping the rezult are bullkrap, any such foul (here) would send the qball away from the target, not help.
<hr /></blockquote>

Which comments are you referring to? I think the only mention of a cue foul are that the cue ball jumps near vertically in the air and the shaft pushes the cue ball over the object ball.

And my basic geometry figures that with 1mm (~0.039 in) gives you 75 degrees to clear the object ball (angle of jump to table; so 15 degrees to the vertical).

cushioncrawler
02-07-2007, 03:32 PM
<blockquote><font class="small">Quote 1hit1der:</font><hr> <blockquote><font class="small">Quote cushioncrawler:</font><hr> The comments about a cue-foul helping the rezult are bullkrap, any such foul (here) would send the qball away from the target, not help.
<hr /></blockquote>Which comments are you referring to? I think the only mention of a cue foul are that the cue ball jumps near vertically in the air and the shaft pushes the cue ball over the object ball. And my basic geometry figures that with 1mm (~0.039 in) gives you 75 degrees to clear the object ball (angle of jump to table; so 15 degrees to the vertical). <hr /></blockquote> I drew 2 small english balls with a 1mm gap and this showed that the qball had an 11dg window -- which i think might equate to about 10dg for the bigger pool balls. I think i see your point about a cue foul possibly helping to get the shot. For example if the qball went vertically up, but here, to meet the qball, the cue would need to be leaning well away "over" the qball, alternatively the cue would at least have to moov throo that space, any of this sort of thing would be obvious i reckon.

But, if u (they) are suggesting that the (foul) cue contact occurs very early on, then that karnt be correct either. The way i see it is that the cue hazta get out of the qball's way to allow the qball to climb, and there is no way that the cue would be able to get back to the qball that quickly, ie to make the foul quicker than the eye.

I suppoze that someone might say that, if u hit down forcefully centrally on a qball, that the qball can be made to jump up (weakly but), and that if a firm hand stops the cue from bouncing up away clear then one can get a sort of foul (i havnt tried this). But, this wouldnt do the trick -- but someone could give it a try i suppoze (i am a long way from a table). madMac.

Jal
02-08-2007, 12:03 AM
The ratio of height/distance of the cueball must be (1/4)tan(a), where "a" is the take off angle measured from the horizontal. This is 1.42 at 80 degrees, and .93 at 75 degrees. After viewing the video frame by frame and taking measurements, the ratio is considerably less than .93 for the shots shown (I skipped one because of perspective).

On the closeups you can also see that the shaft appears to be in contact with the cueball and moving sideways (pendulum style) toward the blocking ball at least until the cueball attains a height of about 3/4 diameter (sometimes more). Although you can't be sure of this, I don't think there is any other explanation for the h/d ratios.

Jim

SpiderMan
02-08-2007, 10:22 AM
<blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote SpiderMan:</font><hr> <blockquote><font class="small">Quote 1hit1der:</font><hr> Interesting discussion brewing on AZ:

Thought I'd post this for those that enjoy the physics and math behind the game. <hr /></blockquote>

I'm with Eric in calling it a foul. The CB "flight path" must be parabolic if there is no additional influence, such as hitting the cue shaft. If the CB never gains enough height to justify a parabolic path that would clear the OB, look for the foul.<hr /></blockquote>I think this is similar to our miscue foul debate. Strictly, under high-speed video scrutiny, highly elevated jump shots (and some masse shots) are fouls. However, to me, the important question is whether it would or could actually be called a foul in league or tournament play.

I think there are several examples of shots that are technically fouls (see the links under "fouls" in the threads summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html)), but they are not called as fouls in leagues or tournaments, even with experienced referees. Regardless, when rules are re-written, these cases should be taken into consideration to eliminate the uncertainty. For example, with the miscue example (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=241789&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;vc=1) we debated previously, maybe the rules could explicitly state: "An unintentional miscue is not by itself a foul, even if the ferule or shaft makes secondary contact with the cue ball." This would avoid the whole debate and make the rules less open to interpretation.

Regards,
Dave <hr /></blockquote>

That's probably close to what is informally practiced now.

I don't know that I'd like to see it written in the rules, though, because the wording "unintentional" implies that someone can actually judge whether the shooter "meant" to miscue.

When I'm asked to referee such a shot, I tend to base my ruling on whether or not I think the shot could have been made clean. If yes, then I consider the miscue as a minor factor and tend to rule it fair. If I don't think the shot is possible clean, then I'm less likely to give the shooter the benefit of the doubt on his intentions. But if the rules were written to remind everyone that I am actually judging intent, then I expect there would be a lot more arguments since only the shooter knows what he was thinking - the ref can't read minds, and everyone knows it.

SpiderMan

dr_dave
02-08-2007, 10:31 AM
<blockquote><font class="small">Quote SpiderMan:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr> <blockquote><font class="small">Quote SpiderMan:</font><hr> <blockquote><font class="small">Quote 1hit1der:</font><hr> Interesting discussion brewing on AZ:

Thought I'd post this for those that enjoy the physics and math behind the game. <hr /></blockquote>

I'm with Eric in calling it a foul. The CB "flight path" must be parabolic if there is no additional influence, such as hitting the cue shaft. If the CB never gains enough height to justify a parabolic path that would clear the OB, look for the foul.<hr /></blockquote>I think this is similar to our miscue foul debate. Strictly, under high-speed video scrutiny, highly elevated jump shots (and some masse shots) are fouls. However, to me, the important question is whether it would or could actually be called a foul in league or tournament play.

I think there are several examples of shots that are technically fouls (see the links under "fouls" in the threads summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html)), but they are not called as fouls in leagues or tournaments, even with experienced referees. Regardless, when rules are re-written, these cases should be taken into consideration to eliminate the uncertainty. For example, with the miscue example (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=241789&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;vc=1) we debated previously, maybe the rules could explicitly state: "An unintentional miscue is not by itself a foul, even if the ferule or shaft makes secondary contact with the cue ball." This would avoid the whole debate and make the rules less open to interpretation.

Regards,
Dave <hr /></blockquote>

That's probably close to what is informally practiced now.

I don't know that I'd like to see it written in the rules, though, because the wording "unintentional" implies that someone can actually judge whether the shooter "meant" to miscue.

When I'm asked to referee such a shot, I tend to base my ruling on whether or not I think the shot could have been made clean. If yes, then I consider the miscue as a minor factor and tend to rule it fair. If I don't think the shot is possible clean, then I'm less likely to give the shooter the benefit of the doubt on his intentions. But if the rules were written to remind everyone that I am actually judging intent, then I expect there would be a lot more arguments since only the shooter knows what he was thinking - the ref can't read minds, and everyone knows it.

SpiderMan <hr /></blockquote>
Good point. The word "unintentional" is probably not a good choice, but the intent of the word choice should be to eliminate uncertainty as much as possible. However, if there are judgments that require knowledge of intent, I think it should be the shooter's responsibility to declare intent if he or she thinks a referee or player might question the outcome. Likewise, if a referee or player suspects that a shot might be suspicious, he or she should ask the player to indicate their intent before the shot.

Regards,
Dave

Fran Crimi
02-08-2007, 11:39 AM
[ QUOTE ]
When I'm asked to referee such a shot, I tend to base my ruling on whether or not I think the shot could have been made clean. If yes, then I consider the miscue as a minor factor and tend to rule it fair. <hr /></blockquote>

I agree with the above criteria providing the following is answered:

Could you guarantee for sure that if a shot is 'scooped' to where the cb is assisted into the air by riding on top of the ferrule, that the ball was definitely struck below center? Can a ball be struck above center and still be scooped? Because if it can, then that would be a problem in using your criteria (above).

Fran