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qstroker2004
09-20-2006, 07:15 PM
My experience with discussion groups is that there is plenty of talk about how to pocket balls, but not so much on knowing where the cue ball is going.

http://CueTable.com/P/?@1AHCU4BIkp4CLVs2PFXk4WLVs4WKxa4WLGb4WLGb2kFXk1kE hX4kMDX4kPev@

You're playing straight pool and want to peel the 3 away from the 2, which is your break ball. Don't worry about strategy -- this is purely a set up to illustrate cue ball control.

Here are 2 questions:
1. Can you predict the cb path toward the 3 well enough to KNOW that you will hit it (and NOT the 2) with natural follow.
2. If you have determined that natural follow will not put you on the 3, can you reliably alter the cb path to make it hit the 3?

This is not a question as to whether it can be done. I'm wondering whether YOU can do it! Think in terms of:

1. Of course I can do this 100% of the time, blindfolded, who can't?
2. I'm probably 50% likely to make that shot.
3. Maybe if I practice it a few times first.
4. Forget the 3 ball, I'm lucky if I pocket the 1!

Thanks - just interested in how good you guys are. /ccboard/images/graemlins/smile.gif

dwhite

dr_dave
09-21-2006, 07:01 AM
<blockquote><font class="small">Quote qstroker2004:</font><hr> My experience with discussion groups is that there is plenty of talk about how to pocket balls, but not so much on knowing where the cue ball is going.<hr /></blockquote>

Not true. See all of the links under "30 degree rule" and "90 degree rule" in the thread summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html). One of the most complete and useful posts is: where the cue ball goes for different cases (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=227461&amp;page =0&amp;view=collapsed&amp;sb=5&amp;o=&amp;fpart=&amp;vc=).

Happy reading,
Dr. Dave

Billy_Bob
09-21-2006, 07:35 AM
<blockquote><font class="small">Quote qstroker2004:</font><hr> ...Can you predict the cb path toward the 3 well enough to KNOW that you will hit it (and NOT the 2) with natural follow.
2. If you have determined that natural follow will not put you on the 3, can you reliably alter the cb path to make it hit the 3?... <hr /></blockquote>

I would be lucky to hit either ball let alone one specific ball in this case. I am getting to where I can sometimes be accurate with a breakout if the balls are fairly close to the object ball I am pocketing.

I would SURE like to know how to be accurate with something like this. I do know that the more I play, the more accurate I get with where the cue ball will go after a shot. So maybe it is just an experience thing?

If anyone has any tips on how they would determine where to hit the cue ball to break these balls out, I would be all ears! (I do know the 30/90 degree rules and use them frequently BTW.)

wolfdancer
09-21-2006, 10:43 AM
BB, you're too modest, I've seen you play some.
Therefore, I'll rate your chances for you:
5. piece of cake

wolfdancer
09-21-2006, 10:55 AM
Dr. Dave, going to "where the cueball goes...." I couldn't open the link (June 05) on the effect of speed.
Have the effects been quantified?

Jal
09-21-2006, 12:25 PM
<blockquote><font class="small">Quote Billy_Bob:</font><hr>I would SURE like to know how to be accurate with something like this. I do know that the more I play, the more accurate I get with where the cue ball will go after a shot. So maybe it is just an experience thing?<hr /></blockquote>It sounds like you're on the right path. When you get it all figured out, let me in on it too, would you?

There is a geometrical way of determining the cueball's final direction for any amount of topspin or draw on it at impact. I posted it once and it fell on deaf ears, as no doubt it will again. But I enjoy the silence, so here goes. (The image is enormous and almost ate up the forum, so I'll just provide a link this time.)

http://ww2.netnitco.net/users/gtech/CBDirection.jpg

The catch is that you have to know the amount of follow/draw at impact in order to locate the equivalent tip offset. If the balls are close to each other and you're hitting hard, no problem. Otherwise, some actual skill is required. With any system, such as Dr. Dave's trisect method for draw shots, you have to know this. There's the rub.

Jim

dr_dave
09-21-2006, 12:54 PM
<blockquote><font class="small">Quote wolfdancer:</font><hr>Dr. Dave, going to "where the cueball goes...." I couldn't open the link (June 05) on the effect of speed.<hr /></blockquote>

Thank you for pointing this out. I reorganized the articles portion of my website. All of the articles can be found here (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html).

<blockquote><font class="small">Quote wolfdancer:</font><hr>Have the effects been quantified?<hr /></blockquote>
Yes, in TP A.4 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-4.pdf), but a bunch of equations and numbers aren't really that useful at the table. Knowing how much to shift the peace-sign hand down the tangent line requires feel and intuition (which can only come with practice). It also depends on ball and table cloth conditions.

Regards,
Dave

dr_dave
09-21-2006, 12:59 PM
Here's a new version of "where the cue ball will go" with active links:

Below is what I think is a pretty thorough (and useful) answer to the question: "Where will the cue ball go?"

For a stun shot, most people know the right answer: in the tangent line direction, perpendicular to the OB direction. This is the 90 degree rule (see my Jan '04 article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2004/jan04.pdf)). If you want a more precise answer that accounts for various effects (e.g., friction and English), see my March-June '05 articles (http://www.engr.colostate.edu/~dga/pool/bd_articles/index.html).

For a rolling CB, the cue ball changes direction by about 30 degrees for a wide range of cut shots (1/4 to 3/4 ball hit). This is the 30 degree rule (see my April '04 article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2004/april04.pdf)). If you want to be more precise, the angle is a little more (about 34 degrees) closer to a 1/2-ball hit and a little less (about 27 degrees) closer to a 1/4-ball or 3/4-ball hit. If you want to know how to account for speed effects, see my June '05 article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2005/june05.pdf). If you want an easy way to use your hand to accurately visualize the cue ball direction, use the Dr. Dave peace-sign technique (see NV 3.8 (http://www.engr.colostate.edu/~dga/pool/normal_videos/NV3-8.htm)). If you want to know how to precisely calibrate your hand for the 30 degree (or any other) angle, see the posting concerning Billy_Bob's finger technique (http://www.billiardsdigest.com/ccboard/showthreaded.php?Cat=&amp;Board=ccb&amp;Number=227266&amp;page =0&amp;view=&amp;sb=&amp;o=&amp;fpart=&amp;vc=).

For a draw shot with good draw action, the trisect system is your answer (see my March '06 article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2006/march06.pdf)). You can use a modified version of the peace-sign technique to predict the cue ball direction (see the article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2006/march06.pdf) for illustrations and examples).

For shots "in between" all of these different cases, the cue ball will go somewhere in between the indicated directions. The only way to get a feel for how much "in between" the cue ball will go is to practice (Fran should like this part /ccboard/images/graemlins/wink.gif).

Regards,
Dave

PS: More info and discussion concerning all of these principles can be found in the thread summary section of my website (http://www.engr.colostate.edu/~dga/pool/threads.html).

wolfdancer
09-21-2006, 03:00 PM
Many thanks...!!!!

wolfdancer
09-21-2006, 03:30 PM
Dr. Dave, a nice series of "where will the cue ball go....if hit by Buddy Hall" videos
either this link:
web page (http://www.billiardclub.net/showarticle.php?articleID=104)
Or this:
web page (http://www.youtube.com/results?search_type=related&amp;search_query=Chalk%20o ff%20pool%20billiards%20instruction%20demonstratio n%209-ball%208-ball%20break%20shot%20pocket%20table%20cleaner%20r eyes%20efren%20rifleman)

qstroker2004
09-21-2006, 04:15 PM
<blockquote><font class="small">Quote Jal:</font><hr>
There is a geometrical way of determining the cueball's final direction for any amount of topspin or draw on it at impact. I posted it once and it fell on deaf ears, as no doubt it will again. But I enjoy the silence, so here goes. <hr /></blockquote>

I think that image needs some text. I have no idea what it is trying to say, which is why you might have heard the crickets chirping last time.

dwhite

Fran Crimi
09-21-2006, 05:52 PM
This doesn't necessarily answer your question but maybe partially. I would consider it a low percentage shot. That's really all I have to know if I were playing a game. That automatically tells me that I shouldn't count on the 2 not moving, particularly since I only get one shot at it in a real game. I can make the one and I can hit those balls on the correct side, but I couldn't guarantee myself with enough confidence that I would leave the 2 exactly where it lies.

You did say you didn't want to hear strategy, but it's hard to ignore it, because once you determine that something is low percentage, then you automatically have to start looking at possible alternatives. If there aren't any, then maybe the move would be to attempt the shot. I see an alternative so I wouldn't attempt the shot that way.

As for how accurate a player can be, I think they can be extremely accurate, but there will always be the 'human' element in execution that can't be measured, only felt.

Fran

qstroker2004
09-21-2006, 06:36 PM
<blockquote><font class="small">Quote Fran Crimi:</font><hr> This doesn't necessarily answer your question but maybe partially. I would consider it a low percentage shot. That's really all I have to know if I were playing a game. That automatically tells me that I shouldn't count on the 2 not moving, particularly since I only get one shot at it in a real game. I can make the one and I can hit those balls on the correct side, but I couldn't guarantee myself with enough confidence that I would leave the 2 exactly where it lies.<hr /></blockquote>

Thanks for the reply, Fran. I think you answer the question in a helpful way because it gives some insight to what "low percentage" means to you. I would like to clarify something, though, because it really helps me understand better. Let's say the 3 and the 2 are side by side from the point of view of the cue ball coming off the 1. Now assume you want to bump the 3 down a few inches or maybe a foot. It is OK if the 2 moves a half inch or so, but you definitely don't want to hit the 2 ball first. Let's say it is OK to make a 1/2 ball hit on the left side of the 3, or hit the 3 full on, or even slightly to the right of center hit on the 3. Is this what you consider low percentage? I'm not talking about contacting the 3 and ending up with another shot, just contacting it as described above.

Thanks,
dwhite

Qtec
09-21-2006, 06:39 PM
[ QUOTE ]
If the balls are close to each other and you're hitting hard, no problem. <font color="blue"> Really? </font color> Otherwise, some actual skill is required. <font color="blue"> Sorry but I have to LOL. [ This is the biggest understatement I have ever heard on a billiards forum. /ccboard/images/graemlins/laugh.gif]</font color> With any system, such as Dr. Dave's trisect method for draw shots, you have to know this. There's the rub.

Jim <hr /></blockquote>

Do you know whats really difficult? Drawing a ball back exactly 5 inches when you really have to be precise.

Qtec

Fran Crimi
09-21-2006, 07:08 PM
Well, I went back and looked at the diagram again and from what it looks like, it seems I could hit the cue ball extremely soft and still contact the 3 on the correct side, so I would have to say that yes, I feel reasonably certain that I could do it while only marginally moving the 2 (forgetting about position, of course). But I would have to be sure I had the correct angle to hit the shot very softly or I wouldn't attempt it.

Fran

dr_dave
09-22-2006, 06:52 AM
Thanks. Buddy's clips are very good.

Regards,
Dave

<blockquote><font class="small">Quote wolfdancer:</font><hr> Dr. Dave, a nice series of "where will the cue ball go....if hit by Buddy Hall" videos
either this link:
web page (http://www.billiardclub.net/showarticle.php?articleID=104)
Or this:
web page (http://www.youtube.com/results?search_type=related&amp;search_query=Chalk%20o ff%20pool%20billiards%20instruction%20demonstratio n%209-ball%208-ball%20break%20shot%20pocket%20table%20cleaner%20r eyes%20efren%20rifleman) <hr /></blockquote>

dr_dave
09-22-2006, 07:04 AM
<blockquote><font class="small">Quote Jal:</font><hr>There is a geometrical way of determining the cueball's final direction for any amount of topspin or draw on it at impact. I posted it once and it fell on deaf ears

http://ww2.netnitco.net/users/gtech/CBDirection.jpg
<hr /></blockquote>
Jim,

I don't think your diagram is self-explanatory. Could you describe it some and maybe give some examples? Otherwise, I would expect a bunch of deaf ears again.

Dave

Jal
09-22-2006, 10:10 AM
<blockquote><font class="small">Quote qstroker2004:</font><hr>I think that image needs some text. I have no idea what it is trying to say, which is why you might have heard the crickets chirping last time.<hr /></blockquote>
<blockquote><font class="small">Quote dr_dave:</font><hr>I don't think your diagram is self-explanatory. Could you describe it some and maybe give some examples? Otherwise, I would expect a bunch of deaf ears again.

Dave <hr /></blockquote>

Thanks for the feedback, Mr. White &amp; Dr. Dave. I did include an explanation last time, but it didn't help. Maybe this is better:

http://ww2.netnitco.net/users/gtech/CBDirection4.jpg

I think this method comes tantalizingly close to being useful but doesn't quite make it. The arrows are kind of small and you have to imagine them in different views where errors can and will be introduced. Normal judgement will likely be as accurate, and probably more so, in most cases.

But it is interesting (to me anyway) that you can get the cueball's final direction by constructing only two lines, both of which are an integral part of the shot. Instead of drawing them as shown in the diagrams, you can also imagine them on the face of the cueball as you address it, where at least the amount of tip offset is directly apparent. But then you have to transcribe the tangent line and the final roll directions to and from the vertical and horizontal planes, where some fuzziness will inevitably occur.

Maybe a more practical application can be worked out. Bob Jewett and Dr. Dave and others have better versions for specific cueball spins.

Dr Dave or anyone else interested, I don't have to tell you that this is an application of the general equation relating the initial velocity and spin of a ball, V and W, to its velocity V' as it reaches natural roll.

V' = (5/7)[V - (2/5)W X R]

where R is the displacement vector from the center of the ball to the point of contact with the cloth (or whatever is rubbing against it). If you feel I have blundered and this is in fact a misapplication of it, any corrections would be appreciated (not so much liked, but appreciated nonetheless). /ccboard/images/graemlins/smile.gif

Jim

cuetable
09-22-2006, 11:40 AM
&gt; 4. Forget the 3 ball, I'm lucky if I pocket the 1!

Most of the time I am lucky /ccboard/images/graemlins/smile.gif

Just want to take this chance to demo the &lt;Tangent Line&gt; function, which
is very useful in this case

From the original by Dan:
http://CueTable.com/P/?@1AHCU4BIkp4CLVs2PFXl4WLVs4WLGb2kFXk1kEYX4kLec8kP ev@

1, Click on the cue ball once
2, Press "h" key to turn on the ghostballs for cue ball (or click on the
&lt;GhostBallOne&gt; button in the toolbox)
3, Click on the ghostball contacting the 1 ball
4, Press "J" key (capital case) to turn on the tangent line (or click on
the &lt;TangentLine&gt; button in the toolbox)

Now you should have this:
http://CueTable.com/P/?@1AHCU4BIkp4CLVs2PFXl4WLVs4WLGb2kFXk1kEYX4kLec4kP evzc1vEYXhkj@

There seems to be appx. 30 degrees gain from the line. With top follow it
might look closer to this on the table (shift-clicking on a ghostball with
toggle its point bt sharp corncer/curve point ):
http://CueTable.com/P/?@1AHCU4BIkp4CLVs2PFXl4WLVs4WLGb2kFXk1kEYX8kDrB8kE RF4kLec8kQkozc1vEYXhkj@

Thank you all for supporting the new table!

Cheers
Wei

CueTable.com

Jal
09-22-2006, 01:03 PM
Qtec,

<blockquote><font class="small">Quote Qtec:</font><hr> If the balls are close to each other and you're hitting hard, no problem. <font color="blue"> Really? </font color><font color="brown">I was refering to knowing the amount of spin the cueball would have at impact, in terms of tip offset. </font color> Otherwise, some actual skill is required. <font color="blue"> Sorry but I have to LOL. [ This is the biggest understatement I have ever heard on a billiards forum. /ccboard/images/graemlins/laugh.gif]</font color> <font color="brown">I think I hold the record for the dumbest post on RSB, the second dumbest here, and now this. Is there some kind of prize, or maybe even annuity I should know about? (and which is offered even if the recipient does not acknowledge their achievemnts)</font color><hr /></blockquote>

Do you know whats really difficult? Drawing a ball back exactly 5 inches when you really have to be precise.<hr /></blockquote>Definitely. But if you manage to draw it back alternately 1 inch and then 9 inches, you can still claim to have pretty damn good control, on average. All seriousness aside, getting the right direction on a cut shot isn't that easy either, which the method tries to address but probably not too successfully as a practical matter.

Jim

dr_dave
09-22-2006, 01:27 PM
<blockquote><font class="small">Quote Jal:</font><hr>Thanks for the feedback, Mr. White &amp; Dr. Dave. I did include an explanation last time, but it didn't help. Maybe this is better:

http://ww2.netnitco.net/users/gtech/CBDirection4.jpg

I think this method comes tantalizingly close to being useful but doesn't quite make it.<hr /></blockquote>

I agree. It is interesting, but doesn't seem very useful at the table.

<blockquote><font class="small">Quote Jal:</font><hr>this is an application of the general equation relating the initial velocity and spin of a ball, V and W, to its velocity V' as it reaches natural roll.

V' = (5/7)[V - (2/5)W X R]

where R is the displacement vector from the center of the ball to the point of contact with the cloth (or whatever is rubbing against it). If you feel I have blundered and this is in fact a misapplication of it, any corrections would be appreciated (not so much liked, but appreciated nonetheless).<hr /></blockquote>

It is not clear to me how your method derives from the equation, but I agree with the equation. It can be verified with Equations 14, 18, and 20 in TP A.4 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-4.pdf).

Catch you later,
Dave

Jal
09-22-2006, 03:01 PM
<blockquote><font class="small">Quote dr_dave:</font><hr>...It is not clear to me how your method derives from the equation, but I agree with the equation. It can be verified with Equations 14, 18, and 20 in TP A.4 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-4.pdf).<hr /></blockquote>Dr. Dave,

Here's a quickie derivation. If you see a problem with it, any help is of course welcome.

If V is the magnitude of the cueball's pre-impact speed, and W its draw or follow spin, then in the expresssion:

V' = (5/7)[V - (2/5)W X R]

the post-impact magnitude of V is Vsin(phi) where phi is the cut angle. And RW = -(5/2)(b/R)V where b is the vertical tip offset (positive for follow, negative for draw). So in terms of the unit vectors along the tangent line (t) and original direction (v), the above expression becomes:

V' = (5/7)[sin(phi)t + (b/R)v]V

If you make the unit vector length equal to the ball's radius, then I think the method indicated in the diagrams follows.

Jim

dr_dave
09-22-2006, 03:21 PM
<blockquote><font class="small">Quote Jal:</font><hr>Here's a quickie derivation. If you see a problem with it, any help is of course welcome.

If V is the magnitude of the cueball's pre-impact speed, and W its draw or follow spin, then in the expresssion:

V' = (5/7)[V - (2/5)W X R]

the post-impact magnitude of V is Vsin(phi) where phi is the cut angle. And RW = -(5/2)(b/R)V where b is the vertical tip offset (positive for follow, negative for draw). So in terms of the unit vectors along the tangent line (t) and original direction (v), the above expression becomes:

V' = (5/7)[sin(phi)t + (b/R)v]V

If you make the unit vector length equal to the ball's radius, then I think the method indicated in the diagrams follows.

Jim<hr /></blockquote>
Thanks. Looks good to me (per TP A.4 and TP A.12 (http://www.engr.colostate.edu/~dga/pool/technical_proofs/index.html)).

The method is valid and very interesting. Although, I still think it is not very useful at the table. Do you agree?

Regards,
Dave

Jal
09-22-2006, 05:39 PM
<blockquote><font class="small">Quote dr_dave:</font><hr>...The method is valid and very interesting. Although, I still think it is not very useful at the table. Do you agree?<hr /></blockquote>Thanks for the verification. It's always good to have a second opinion, particularly someone such as yourself on these matters.

On the face of it, I also doubt that it's useful. But it's borderline with me. If you trained yourself to visualize how these two things, the sine of the cut angle and tip offset, add up to the final ball direction, it might provide another helpful clue as to what the cueball will do.

I think the main thing that goes against it is the short length of the arrows, and specifically, trying to size up the sine of the cut angle (red arrow in the diagram). But maybe there's a better way of doing it? I'd be interested in your criticism of it.

Jim

dr_dave
09-23-2006, 10:24 AM
<blockquote><font class="small">Quote Jal:</font><hr> <blockquote><font class="small">Quote dr_dave:</font><hr>...The method is valid and very interesting. Although, I still think it is not very useful at the table. Do you agree?<hr /></blockquote>Thanks for the verification. It's always good to have a second opinion, particularly someone such as yourself on these matters.

On the face of it, I also doubt that it's useful. But it's borderline with me. If you trained yourself to visualize how these two things, the sine of the cut angle and tip offset, add up to the final ball direction, it might provide another helpful clue as to what the cueball will do.

I think the main thing that goes against it is the short length of the arrows, and specifically, trying to size up the sine of the cut angle (red arrow in the diagram). But maybe there's a better way of doing it? I'd be interested in your criticism of it.<hr /></blockquote>
Jim,

Thanks again for the detailed clarification and for posting the graphic in the first place ... very creative graphical interpretation. Did you come up with that or did you see it somewhere else. I haven't seen it before. I don't have any further ideas or criticism concerning the method.

Catch you later,
Dave

IA8baller
09-23-2006, 04:35 PM
My personal answer would be between #1 and #2.........I could hit that shot, make the ball and peel away the other ball better than 50% of the time but definitely not 100%, if I had to give a true estimate of myself it would be in the 60 to 70 % of the time. /ccboard/images/graemlins/cool.gif

qstroker2004
09-23-2006, 06:51 PM
<blockquote><font class="small">Quote IA8baller:</font><hr> My personal answer would be between #1 and #2.........I could hit that shot, make the ball and peel away the other ball better than 50% of the time but definitely not 100%, if I had to give a true estimate of myself it would be in the 60 to 70 % of the time. /ccboard/images/graemlins/cool.gif <hr /></blockquote>

So are you a 100 ball runner?

thanks,
dwhite

IA8baller
09-24-2006, 04:36 AM
<blockquote><font class="small">Quote qstroker2004:</font><hr> <blockquote><font class="small">Quote IA8baller:</font><hr> My personal answer would be between #1 and #2.........I could hit that shot, make the ball and peel away the other ball better than 50% of the time but definitely not 100%, if I had to give a true estimate of myself it would be in the 60 to 70 % of the time. /ccboard/images/graemlins/cool.gif <hr /></blockquote>

So are you a 100 ball runner?

thanks,
dwhite <hr /></blockquote>

100 ball runner straight pool? I've never played straight pool so I honestly don't know.


Can I pot 100 balls in a row practicing?.....Not sure, never tried to concentrate on just that factor. I know I've run out 5 racks in a row (all 15 balls) while practicing before, so maybe I'm a 75 ball runner?

I guess I need to play some straight pool and find out.

cram
09-24-2006, 11:47 AM
Dave, can you explain the reason why it is necessary to elevate the cue in the second shot here:
http://www.youtube.com/watch?v=3ibrOOtotYo
It seems that it aggravates the curvature but I don't understand (physically speaking) why?
Thanks,
Marc

Jal
09-24-2006, 12:09 PM
<blockquote><font class="small">Quote dr_dave:</font><hr> ....Did you come up with that or did you see it somewhere else. I haven't seen it before.<hr /></blockquote>Dr. Dave,

Many thanks for the generous remarks. I believe I came up with it. The closest method that I've seen is Bob Jewett's which is described here:

http://www.sfbilliards.com/articles/2001-06.pdf

Since I really didn't understand his version very well until recently, I don't think I could have stolen it off of him, even unconciously. His has the advantage that you can draw the lines to just about any scale you want, but the tip offset isn't so directly readable.

I've been looking at finding where the ball reaches natural roll with a similar method. This would nail down which parallel path the ball will take. It's really not as difficult as I thought it would be, but you have to know the cueball's speed in absolute units and draw to some fixed scale. Something to think about but certainly seems even less practical than just getting the direction.

Jim

Rod
09-24-2006, 05:00 PM
<blockquote><font class="small">Quote cram:</font><hr> Dave, can you explain the reason why it is necessary to elevate the cue in the second shot here:
http://www.youtube.com/watch?v=3ibrOOtotYo
It seems that it aggravates the curvature but I don't understand (physically speaking) why?
Thanks,
Marc <hr /></blockquote>

I'm not Dave but, itís a masse shot which serves to straighten the angle a bit before contact. After contact it continues to curve to the left. Top left by it self (and a level cue) would never bring the c/b back that low. The reason is the c/b is struck on a horizontal plane which has straight forward momentum. A masse type stroke (elevated 45 degrees) spins the c/b on more of a vertical plane and less forward momentum. Shooting vertical there is more friction against the cloth opposing a straight forward direction. Bottom line it will curve to the left more.

Rod

dr_dave
09-25-2006, 07:17 AM
<blockquote><font class="small">Quote cram:</font><hr> Dave, can you explain the reason why it is necessary to elevate the cue in the second shot here:
http://www.youtube.com/watch?v=3ibrOOtotYo
It seems that it aggravates the curvature but I don't understand (physically speaking) why?<hr /></blockquote>
Maybe Rod's post answered your question. If not, here's another explanation:

Cue stick elevation creates spin that makes the curve ball masse (curve) to the left (mostly after collision with the object ball) to straighten the path into the rail. There, the left English takes and helps bring the cue ball even more to the left. HSV A.127 (http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-127.htm) is the best clip I have to illustrate the direction of masse spin.

Regards,
Dave

PS: FYI, my Nov'05 instructional article (http://www.engr.colostate.edu/~dga/pool/bd_articles/2005/nov05.pdf) discusses masse shot aiming. It doesn't directly apply to the question at hand, but it might help improve your understanding of masse shots.

cram
09-25-2006, 09:29 AM
Dave wrote: Maybe Rod's post answered your question.

Marc: Yes, it did; I responded to him via my mailbox but it doesn't appears on the site?!

If not, here's another explanation:

Cue stick elevation creates spin that makes the curve ball masse (curve) to the left (mostly after collision with the object ball) to straighten the path into the rail. There, the left English takes and helps bring the cue ball even more to the left. HSV A.127 is the best clip I have to illustrate the direction of masse spin.

Marc: Thanks a lot!

Regards,
Dave

PS: FYI, my Nov'05 instructional article discusses masse shot aiming. It doesn't directly apply to the question at hand, but it might help improve your understanding of masse shots.

Marc: Thanks for this and for all your articles and video's. The 30 and 90 degree's articles and diagrams helped me to understand the reasons of the path of the CB