pause before pulling the trigger?

[mikepage]

Does any of this really have anything to do with the game of pool? In over 40 years of playing the game, I have never had a shot that required me to throw the cue ball straight up in the air and try to decide if it stopped at the top or not. I have, however, had thousands of shots that required me to move my cue stick forward in a straight line. The pause between backward and forward motion helps make that happen with a smooth transition. It seems like we may have a little "overanalysis" going on that really doesn't make much difference when it comes to being better players.
JMHO
Steve

You're certainly right Steve. This has gotten way off track and includes a lot of stuff that matters no more than do sharp points on a cue.

And you're certainly right that moving the cue in a straight line with a smooth transition between the back and forward motion is what is important.

But what some people, including even some instructors, don't realize is that it's possible to make a jerky transition with or without a pause, and it's possible to make a smooth transition with or without a pause. Some people have actually still maintained that "everybody pauses at the backstroke." Those people are wrong. And the esoteric directions we have taken have been related to helping those people to understand the fallacy of their reasoning. Nobody is suggesting that anyone needs to include in actual instruction these nuances. But instructors should stop saying things that are wrong.

The fact is some people pause, and others don't. And that's OK.

 

[Scott Lee]

But what some people, including even some instructors, don't realize is that it's possible to make a jerky transition with or without a pause, and it's possible to make a smooth transition with or without a pause.

certainly true

Some people have actually still maintained that "everybody pauses at the backstroke." Those people are wrong.

IMO, and others, NO we're not!

And the esoteric directions we have taken have been related to helping those people to understand the fallacy of their reasoning. Nobody is suggesting that anyone needs to include in actual instruction these nuances. But instructors should stop saying things that are wrong.

The fact is some people pause, and others don't. true again...and the good ones do it on purpose! And that's OK.

Mike...Just because YOU think you're right does not make those instructors who maintain that all GOOD strokes include some sort of pause at the backswing wrong (whether it is momentary or by design). You and some others have gone so far out of your way to make b.s. 'technical' definitions the crux of this whole thread. Why?...apparently because you don't like our 'definition' of what we consider to be a "pause". Still doesn't make you right, and us wrong. We don't accept your 'definition' and you don't accept ours...why not just leave it at that? If it helps the student to use any definition that suits them, in furthering their own pursuit of a better stroke, then so be it. Geez...leave it alone, will ya?

Scott Lee
www.poolknowledge.com

 

[FLICKit]

Duly noted... You are obviously right, not 10 ft/s/s but 32 ft/s/s or 10 m/s/s... Yeah you're also right about no upward limit... My stupid mistakes there aren't helping...

I agree we can treat it as 1-dimensional motion. But I would not use x. The reason is gravity, which only acts in y, contributes to the restoring force. So a better way to do it is to talk about motion in the x-y plane. Let's say we're talking about motion of the grip hand. The grip hand is attached to the fixed elbow, and the coordinate for the one-dimensional motion is theta, the angle from vertical.

It seems to me that some people who have been engaging in this conversation in this thread may have been focusing solely on the x component. Whereas you and others are focusing more on the x and y components, thus the whole plane as you stated.

This is an important clarification. By eliminating that confusion, it helps all involved to forward the conversation.

I think even looking at the stroke in the x-y plane, we can still simplify the discussion by isolating the x component. Thus people are referring to the backward stroke (negative x) and the forward stroke (positive x). At issue in this thread, is whether there is a pause (zero x) distinguished from the backward stroke and the forward stroke.

Of course the effects of gravity in a pendulum swing impacts the x-y movements such that it moves at a VELOCITY that is NOT CONSTANT. But the effects of gravity in a pendulum swing impacts the x-y movements in a manner that is CONSISTENT and in accordance with acceleration at a rate of 32 ft/s/s. (stating the obvious here)


OK, in addition I understand your issue with the use of the word equilibrium, because equilibrium refers to stable over a length of time...

Ouch, it almost hurts to read that word, but if you replace equilibrium with zero speed, then OK.

Thus, I concur with you here as well.

Yes for the rate of change of distance.
No for the rate of change of speed.

The rate of change of speed is the same everywhere.

Here you may have misunderstood...
You agree that the rate of change of distance is altering.
Since velocity = distance / time then the velocity is altering.

Now, if you're referring to the acceleration, then yes the acceleration is the same.

At any point in this trajectory, including the top, the ball is accelerating downward at 10 (m/s)/s.

Yes, and simultaneously the velocity is decreasing from interval to interval in respect to the y coordinate system (using the ball in air example).

ft/s
----
16 - initial velocity
8 - v reduced by 8 decreasing in magnitude
4 - v reduced by 4
2 - v reduced by 2
1 - v reduced by 1
0 - v reduced by 1 now will increase in magnitude
1 - v reduced by 1 and is now heading in the negative direction
2 - v reduced by 1
4 - v reduced by 2
8 - v reduced by 4
16 - v reduced by 8

 

[td873]

The fact is some people pause, and others don't. And that's OK.

Actually, the fact is that technical natured folks import the physics definition of "pause" into pool while others rely on the vernacular use of "pause." This invariable results in a sematic argument, rather than an argument of any merit. Any novice debater will automatically revert to their definition, and thus never accept the other position. Once you have a non-losing premise, the other side is ALWAYS wrong, eh?
The answer is: both sides are right, and both sides are wrong - depending on where you start.

This is just another manifestation of the 2 known camps:
(1) the stop thinking and start playing camp; and
(2) the I like to understand as much as possible camp.

I think I like the deflection discussions better, as since you can't escape endmass - and "endmass" isn't something used in the vernacular

Although I am always interested in the technical, IMO (only), using/reverting/relying on calculus in a Pool Forum is a Thread Killer and is not serving any purpose for the general masses. Rather, it comes across as a bit pretentious and looks like a self-ego stroke. To me -> that's why they have PMs and email. But what do I know.

-td

 

[FLICKit]

OK, I re-read the thread....

Sounds like Bob and others have defined "pause" to be a stop over a length of time. Since the zero velocity is not for a significant enough length of time, therefore the word pause doesn't apply. Making the whole discussion trivial...

 

[Bob Jewett]

Does any of this really have anything to do with the game of pool? ...

Actually, it's not clear that it does, unless you want to understand more deeply what happens physically on the table. I think it does have something to do with teaching pool. I think instructors should understand the technical stuff to avoid making technical mistakes when talking to students. If an instructor is not bothered by saying things that are technically false but still get the point across to students, then it probably isn't important to him, either. There's also the problem that you will occasionally run into the student who does understand the technical details, and then it is better if you don't insult his intelligence too badly.

 

[pooltchr]

Bob,
Point taken. I, like you and many other instructors, am always trying to learn as much as possible. I try very hard to only give factual information to my students. I also try to show them things that will help them become better players. The point I was trying to make was more about this particular thread. I think the discussion has gotten so technical that it is of little value to actually helping anyone improve. One side digs in their heels and says there is no pause when changing direction, the other side says there is. But what we teach is that if there is a deliberate pause, chances are improved for a smooth transition. Whether or not there is a point of zero motion isn't as important as whether or not the stroke is smooth.

What we teach may not be for everyone...but for the vast majority, it works very well. There is always going to be some who choose to go a different way. That's what makes each person an individual.

I met with a potential student yesterday. We talked for a couple of hours. The first thing I saw when he shot was the worst case of chicken wing I have ever seen. He knew it, and felt strongly that he wasn't going to change it. The next thing I observed was his cue actually moved straight forward. (I'm still trying to figure out how...but he has found a way to make it work consistantly). In the end, we agreed that there were other areas that we could work on that would help him. I have no intention of trying to make him see it my way, although I think he could be an even better player if he were to consider changing. We had to agree to disagree. We will just work on things that we both agree can benefit his game. I'm not going to get into a discussion of the physiology of the pendulum stroke, since it would be of little value to his game. We will just focus on how to make him a better player. That is what he wants, and I will commit togiving him the best I have. We have to taylor our instruction to the individuals we teach. Most of my students are much more concerned with making the shot and getting position, than with the technical aspects we have been discussing here.

I agree that a working knowledge of physics is important when teaching anyone about pool. I guess I just think you can get sidetracked in the extreme technical aspects, and forget that the bottom line is helping them move their cue forward in a straight line.

Steve

 

[av84fun]

That's because so far as I know nobody in the history of the universe has claimed that.

Well, Bob did. Read the thread.

And besides, what constitutes an authority on this subject?

How about one of the co-authors of the white paper entitled:
Reality and Theory in a Collision by Norman Derby (Bennington College) and Robert Fuller (University of Nebraska)

Below is a copy of my e-mail to Mr. Derby and his reply.

I have stated multiple times and will again here that I agree that whether an object stops for a millisecond or for a zero length of time before reversing direction has nothing to do with the pool stroke. It is just an interesting topic in my view as your responses and several others show.

But I think it is time, for me at least, to turn my attentions elsewhere so as not to exhume a dead horse in order to keep beating on it!

With kindest regards,

Jim

NOTE: The article mentioned happens do deal with collisions in pool balls and is a VERY interesting. Here is a link.

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1002&context=physicsfuller

-----Original Message-----
From: AV84fun@aol.com [mailto:AV84fun@aol.com]
Sent: Sat 11/3/2007 10:13 PM
To: Derby, Norman
Subject: Reality and Theory in a Collision

Hello Mr. Derby,

I just happened upon your article in collaboration with Mr. Fuller. I am a
pool player so the findings had more than academic interest for me.

I am curious about one issue about which you wrote. At the moment of
collision, you state that:

"The solution of this model is straightforward. Immediately after the
collision, the cue ball has lost all
its linear momentum..."

Is it your view, in other words, that upon impact with the object ball, the
cue ball stops dead before continuing forward?

And similarly, if there was draw imparted to the cue ball such that upon
object ball impact it would reverse directions, is it still true that however
briefly, the cue ball would stop for a measurable increment of time before
reversing direction?

In fact, do ALL objects in one dimensional motion come to a complete stop
before reversing direction?

There seems to be some debate on that topic and I would greatly appreciate
your views...or a link to some reference on point.

THANKS!

Jim





Hi Jim,

Let me see if I can shed light on your 2 questions.

One seems to be philosophical in nature. If an object reverses direction, must it come to a halt at some point? Yes. Our understanding of physics says that any object with momentum can change its momentum ONLY by interacting with something else (that's the essence of the law of inertia). We describe that interaction by saying that these 2 things exert forces on each other. To produce a finite change in momentum in zero time would require an infinite force, so this does not happen in the real world. At fast enough frame rates you'd always see the object slow down, stop and then begin to speed up in the other direction.

Did our incoming ball stop completely when it collided with the stationary ball? Within the limits of the video we used, it did. If you've seen the kid's top known as Newton's Cradle (with colliding steel balls) then you've seen the dropped ball hit one (or more) and the one other ball take off with nearly all the momentum. While pool balls aren't quite as hard as ball bearings, they would be expected to behave in much the same way. The behavior of hardball collisions is fairly simple because they remain in contact for such a short time period (there is so little deformation of the balls) that the forces they exert on each other are HUGE for a short time during which all other forces (like the tabletop) are comparatively insignificant.

Hope that's helpful,

Norm Derby

 

[9ballprodigy]

man, this thread has deviated so far away from the original subject and intentions...

 

[mikepage]

Actually, the fact is that technical natured folks import the physics definition of "pause" into pool while others rely on the vernacular use of "pause." This invariable results in a sematic argument, rather than an argument of any merit. Any novice debater will automatically revert to their definition, and thus never accept the other position.

Look, I've been on here or RSB for ten years. I think people who have known me for a long time know I wouldn't waste my time on a merely semantic issue. And I've actually addressed this--that the problem is more than semantics--before.

I and others say a pause requires the first and second derivatives (speed and acceleration) to be zero, or equivalently for the speed to be zero and, at least briefly, remain zero.

If someone else wanted to define a pause as merely the speed going through zero, then that's fine. I might suggest their definition is unconventional and might lead to confusion, but I wouldn't go any further.

The problem is more than that.

The problem is there is a real, important, physical difference between stopped for no length of time and stopped for a length of time and that difference is the latter requires extra forces applied by the arm to make it true. If you define pause as I do, as the latter, then you can
draw a distinction between the first (no pause) and the second (pause).

If you choose the word pause to include both, then it is incumbent on you to find some other way to make the real distinction. You could have type 1 pause and type 2 pause, or you could have instantaneous pause and extended pause. But if you fail or refuse the make the distinction, that is a problem, imo, especially because we have top players that do either one, and we have instructors that advocate either one.


Here is an Olympic weightlifter talking about the benchpress:

CONTROL JAY CUTLER

For a lot of pros, when they're working a bodypart, you'll see some motion in the rest of their bodies. When they're pushing heavy weight, it's almost impossible not to use a lot of muscles. I do the same, but usually with the rest-pause principle. I contract the muscle as much as I can, but I don't do continuous repetitions at a steady pace, like a machine. My training is different from Ronnie's in that manner. His is explosive: up, down, up, down, consistently paced, with no pause, for 10 reps. Mine pause. For squats, I go down, come up and squeeze the quads for a one- or two-count, go back down, come up and squeeze for a one- or two-count, etc.

For bench presses, I pause at the top of every third rep or so, and when I come down, I control the bar so that it stops about two inches shy of my chest; i.e., I don't bounce it off my chest. That's what I consider strict.
[...]

I think everybody knows what he means. He uses pause the same way I do. I'm sure he wouldn't deny the weights are stopped for an instant at the top for everybody. But I imaging he's well aware of the extra forces required to keep them there.

This is just another manifestation of the 2 known camps:
(1) the stop thinking and start playing camp; and
(2) the I like to understand as much as possible camp.

I would say instructors have some responsibility to wade in the type 2 waters even if their personal approach and teaching style puts some emphasis on type 1.

I think I like the deflection discussions better, as since you can't escape endmass - and "endmass" isn't something used in the vernacular

It's funny. I see the opposite. Endmass is only really defined by it's effect: the ball squirted like this, so the end mass was 0.321 OZ. The actual relation of this 0.321 OZ to the mass distribution in the stick is something we're all pretty clueless on.

Although I am always interested in the technical, IMO (only), using/reverting/relying on calculus in a Pool Forum is a Thread Killer and is not serving any purpose for the general masses. Rather, it comes across as a bit pretentious and looks like a self-ego stroke. [...]

I think this is unfair, but then again it's me you're complaining about.

 

[Fatboy]

point in this trajectory, including the top, the ball is accelerating downward at 10 (m/s)/s.

I awalys thought the acceleration of gravity was 9.8 (m/s)/s not 10

 

[td873]

I think this is unfair, but then again it's me you're complaining about.

Not true. I always compliment your efforts and try to contribute where I can. For example, see post 66and 40 in this thread. I have applauded you on other occassions as well. There is no need to feel like you are being singled out, or that your efforts are unappreciated. But to "require" the non-technical to adopt the techinical definition (and all the associated baggage) is a form of educational imperialism. There is no reason that they cannot continue to believe that there is a "pause" at the point of a two-dimensional direction change. Even if there is no non-zero pause. [Ignorance is bliss].

The truth is: the majority of the pool world will never participate in, or even appreciate, the technical nature of analytical discussions. Thinking otherwise is unrealistic.

... I and others say a pause requires the first and second derivatives (speed and acceleration) to be zero ...

... If someone else wanted to define a pause as merely the speed going through zero, then that's fine...

...If you define pause as I do, as the latter, then you can draw a distinction between the first (no pause) and the second (pause).

IMO, this emphasizes the apparent semantic nature of the argument. EVEN IF the technical definition IS CORRECT, the non-technical are not encumbered by a non-zero pause...

Besides, EVEN IF camp 2 is wrong, nothing is gained by proving camp 1 is right. Only those interested in understanding will embrace the correct defintion - despite the simplicity of the argument.

Lastly, perhaps there should be a "technical" area on AZ so that the analytical folks can congregate and discuss the physics of pool. The newbies and inquisitive could visit at their leisure...

-td
[edited]

 

[Bob Jewett]

...
However, the truth is: the majority of the pool world will never participate in, or even appreciate the technical nature of analytical discussions. Thinking otherwise is unrealistic.

-td

That's certainly true, but I think anyone who aspires to be a "master" instructor should at least make some effort to learn the technical aspects of the game. It can give them insights into how to teach better and keep them from telling their students things that are not only false, but sometimes harmful to their improvement.

And for those who think the differences about the word "pause" are purely semantic, I offer you a quote that may help:

You do not know what you do not know.
-- Mohandas (later Mahatma) Ghandi in a South African court in 1912​

 

[td873]

That's certainly true, but I think anyone who aspires to be a "master" instructor should at least make some effort to learn the technical aspects of the game. It can give them insights into how to teach better and keep them from telling their students things that are not only false, but sometimes harmful to their improvement.

Agreed. But you will always have black sheep...

And for those who think the differences about the word "pause" are purely semantic, I offer you a quote that may help:

And (just to be a little pedantic ) since we are so heavily relying on definitions, this actually IS a semantic argument when you use the REAL definition of semantic: "Semantic adj: of or relating to meaning, esp. meaning in language." Websters II, American Heritage, OED. Doh!

Lastly: Do any technical gurus object to the use of "stop at the end of the backswing" instead of "pause at the end of the backswing"?

-td

 

[teebee]

From what I can tell the teachers that advocate a pause in the swing, advocate a true pause in it's technical definition, a zero velocity for a duration of time. The problem arises when the claim is made that you can't perform a pendulum swing without a pause. By it's technical definition (what other kind is there?), it definitely can. A pause is a pause just as Mike says. Accentuate its role in the swing or down play it but don't say that a swing can't be made without one and everyone would be in agreement.

 

[Williebetmore]

And (just to be a little pedantic ) since we are so heavily relying on definitions, this actually IS a semantic argument when you use the REAL definition of semantic: "Semantic adj: of or relating to meaning, esp. meaning in language." Websters II, American Heritage, OED. Doh!

Lastly: Do any technical gurus object to the use of "stop at the end of the backswing" instead of "pause at the end of the backswing"?

-td

td,
Well said (perhaps BJ's degree is in physics and not English).

The discussion of ball/gravity is not strictly applicable to a pool stroke (where muscular force rather than gravity is providing the motion); that's all I was pointing out (and neither of the bickering parties even started the analogy). I fail to see how presence or absence of a pause at the top of a baseball toss has ANYTHING to do with pool (and any discussion of the issue; whether the discussant is correct or incorrect; is DEFINITELY a semantic discussion IMO)....perhaps it could be moved to the NPR forum. Hell, it would be hard to find any thread on this forum that could not be considered a semantic discussion.

Anyway, BJ should NOT have mentioned Mahatma (?Mohandas?) Gandhi in this thread (NPR!!!)....he should have quoted Danny DiLiberto (a much greater thinker), "If you knew what you didn't know, then you wouldn't not know it."

 

[Scott Lee]

Bob...There are more Master instructors who believe what I believe, and promote, than follow your semantic conjecture. They DO know the technical aspects (as do I). We just choose to teach them in a different framework. Let's be simplistic here...we'll call your way "old school" (not saying that is incorrect or bad), and our way "new school" (which we believe to be better at communicating sophisticated concepts from a layman's point of view). So, regardless of your continuous efforts to make out some of what we do or say to be "false", it is still true in our eyes, and works well with our students... which, imo, is the most important thing. Here's what it finally boils down to when it's all said and done...DIFFERENT STROKES FOR DIFFERENT FOLKS!

Scott Lee
www.poolknowledge.com

That's certainly true, but I think anyone who aspires to be a "master" instructor should at least make some effort to learn the technical aspects of the game. It can give them insights into how to teach better and keep them from telling their students things that are not only false, but sometimes harmful to their improvement.

 

[Scott Lee]

Don...I think Danny might have paraphrased that line from our fellow instructor, the great and mighty Oz...who has stated for many years, the undeniable truism: "They don't know what they don't know!"

Scott Lee
www.poolknowledge.com

BJ should have quoted Danny DiLiberto (a much greater thinker), "If you knew what you didn't know, then you wouldn't not know it."

 

[av84fun]

FLICKit..."It would be exactly as if at the highest point of the ball's flight, there was a table underneath it for an instant and then removed. "

Right, but as you have read, there are those who disagree that the "table was underneath it" thereby preventing its downward motion...i.e. stopping...for even an instant.

Regards,
Jim

 

[av84fun]

Does any of this really have anything to do with the game of pool?

Not really as I have stated several times...but it is interesting to several of us.

(-: