Peak Acceleration In Your Stroke?

[Patrick Johnson]

klockdoc:
...if it is hitting the ball with a draw spin, it will draw after contact.

Me:
...I guess you mean back toward the rail, and I still maintain it won't happen.

klockdoc:
Yes you are correct. Backwards = draw

If the CB hit an OB before hitting the rail, the draw spin would draw the CB back away from the rail, right? So "backwards" means "away from the rail" (at whatever angle). This doesn't change after the CB hits the rail and changes direction - the spin will still take the CB away from the rail. In this respect it's the same as when shooting almost straight into the rail - "away from the rail" spin remains "away from the rail" spin, before and after hitting the rail and no matter what you call it.

pj
chgo

 

[klockdoc]

Still looking for a video to show you what I am talking about. If I can't find one, I guess I will make one. Anyway, found this. Note what Mike Page states and Jal. The last paragraph of Jal's post is talking about what we were discussing. Everything else I agreed with.

Also, notice the last paragraph of Mike's post.

Lets say an object ball is a few balls widths off the rail, and you are hooked. You kick into the rail at an angle so that it hits the object ball full. If you do hit the OB full, do you use top or bottom to get the cueball to draw back? Logic tells me that it would be reversed since the cueball is coming towards the OB at an opposite angle. So would you use topspin to draw the cueball off a kick shot? Or is it still draw, and can someone please explain the physics of it? Thanks

While the details depend on the rail gutter, the nose height, and the stickyness of the cloth on the cushion, the general result is that balls tend to lose all their top or bottom spin and come off a cushion sliding.

Unless you have unusually slick (i.e., new) cloth or have overspin, you're not gonna get draw after hitting an object ball off the cushion.

That's coming directly off the cushion though. Going into the cushion at an angle is a horse of a different color. You can get all sorts of wicked safeties hitting these kicks for a nearly full hit with draw. I suppose what's happening is the component of the backspin acting perpendicular to the rail is wiped out by the cushion, while the component acting parallel to the rail is still there and can be used to tuck the cueball in behind the second (offending) object ball.

mike page
fargo

In addition to what the other posters have said, the dividing line is approximately at a 45 degree incoming angle to the cushion. If you're coming in at less than this, use draw. If greater, use follow. The cushion itself imparts a little bit of a draw component since the spin it puts on the ball is tilted by about 15.7 degrees from the vertical, which is due to the cushion being a little higher than the center of the cueball. (This is a completely useless fact but I thought interesting in this context ).

As Mike Page stated, the more perpendicular you come into a cushion, the more spin gets rubbed off. For a perfectly perpendicular shot at least, the amount of follow that is left (now effectively draw) is very sensitive to the amount of friction present and the cushion height. It may or may not have any spin left after it rebounds depending on the particular table.

If it has draw going into the cushion, all of it is removed. The difference is that, in the case of draw, friction with the cushion nose drives the ball down into the table bed (rail gutter), adding to the compressive downward force that the cushion applies to the ball (again due to nose height). So the ball experiences considerable friction from both the cushion and the bed, although much greater from the cushion.

In the case of topspin (follow) going in, the frictional force with the cushion nose opposes this downward compression force, and as a result there is very little overall downward force and thus friction with the bed.

As you make the incoming angle more shallow, the orientation of the friction force with cushion becomes less vertical and more horizontal. The torque from this is at a right angle to both the friction force and to the radius moment arm drawn from the center of the ball to cushion nose. This perpendicularity makes it go from less horizontal to more vertical. Since an angular momentum component always develops in the direction of the torque (the torque points in the direction of the newly developing spin axis), and since it is now more vertical, it won't cancel any existing follow or draw as readily since the angular momentum components for draw or follow are always horizontal. In brief, less spin is removed (although all of it might still be removed until the angle becomes shallow enough).

Well, you asked for a physics explanation. Hope it helped a little.

Jim

 

[Andrew Manning]

I don't get it; Patrick Johnson is saying things, and av84fun isn't stalking/shouting him down. Did he finally get banned for that or something? If so, it's about time.

-Andrew

 

[Patrick Johnson]

klockdoc:
Note what Mike Page states and Jal.

I don't think what either of them said is about the same thing we're talking about. But this is getting too far into semantics to make any sense of any more. I'll wait for your video.

Sorry I couldn't make myself more clear...

pj
chgo

 

[Patrick Johnson]

I don't get it; Patrick Johnson is saying things, and av84fun isn't stalking/shouting him down. Did he finally get banned for that or something? If so, it's about time.

Well, I obviously agree with you, but I admit I have a hard time ignoring his nonsense. Wish I was better at it.

pj
chgo

P.S. I'm outta here before the 12-page posting history ramble begins...

 

[av84fun]

I don't get it; Patrick Johnson is saying things, and av84fun isn't stalking/shouting him down. Did he finally get banned for that or something? If so, it's about time.

-Andrew

Patrick Johnson
Quote:
I don't get it; Patrick Johnson is saying things, and av84fun isn't stalking/shouting him down. Did he finally get banned for that or something? If so, it's about time.


Well, I obviously agree with you, but I admit I have a hard time ignoring his nonsense. Wish I was better at it.

pj
chgo

Andrew, I was genuinely disappointed to read your post but I just as genuinely support the expression of your opinion on that subject.

You may not have noticed that BOTH Patrick and I were warned by Mr. Wilson about making further rude/abbusive posts...a warning that I have strictly adhered to and which Patrick has repeatedly ignored.

IMHO, a more careful reading of the post history between myself and Patrick would show that, while it is true that we have disagreed on a number of issues, he has been clearly incorrect on several occasions...such as his recent assertion that the forearm should be held in the vertical position at cue ball address.

In addition, such a review would make it clear that in the vast majority of cases, Patrick was the initiator of rude and often vulgar insults to me...and not the other way around.

I don't recall having had any acrimonious disputes with you but if I did post offensively to you, I apologize.

Regards,
Jim

 

[klockdoc]

I don't think what either of them said is about the same thing we're talking about. But this is getting too far into semantics to make any sense of any more. I'll wait for your video.

Sorry I couldn't make myself more clear...

pj
chgo

I guess in a nut shell;

I am saying that I can kick off the side rail (at a shallow angle as shown in earlier posts diagrams), hit the object ball with backspin and draw the CB back behind another set of balls.

You say it cannot be done.

I thought these posts of Mike and Jal somewhat confirmed that at least I wasn't out-of-my-mind by suggesting such an idea and stating that I have accomplished this many times playing safe in games.

But Patrick, think of it this way. If a CB lost its draw spin when shot into a side rail at a shallow angle, then you wouldn't be able to accomplish shots such as the one in the diagram below. If the draw spin is present here, it must still be present in my proposed shot. ( I am sure it loses some spin, but, if the object ball is hit with the correct fullness, it will draw back after contact)

Thanks for the discussion. I will try to locate a video.

CueTable Help

 

[Patrick Johnson]

I am saying that I can kick off the side rail (at a shallow angle as shown in earlier posts diagrams), hit the object ball with backspin and draw the CB back behind another set of balls.

You say it cannot be done.

I don't make the blanket statement that "you can't draw back behind another set of balls" - you can do that if it doesn't involve drawing the CB back toward the rail. The reason, as I've said a few times, is that the draw spin on the CB can't change direction, and its direction is away from the rail.

Here's a diagram to illustrate what I mean by that:

CueTable Help

When you hit the CB with draw spin, the draw spin has a specific direction, which is directly opposite the initial direction of the CB (as shown by the red arrow from ghost CB "A"). If, instead of hitting the rail, the CB hit another ball dead on, it would stop momentarily and then return along the same path that it came in on (along the red arrow). This direction, as shown in the diagram, is both to the left (toward the foot rail) and downward (away from the side rail).

When the CB hits the rail its direction of travel changes, but the direction of its draw spin does not change - it is still spinning toward the foot rail and away from the side rail. Therefore, if the CB is stopped by another ball (the 1 ball in the diagram) it will stop momentarily and then draw back along a path that's parallel with its initial path, along the blue arrow shown by ghost CB "B".

The CB's draw spin doesn't change direction, and therefore it will always move the CB toward the foot rail and away from the side rail. The CB can move back toward the side rail, but only if some other force acts on it (like caroming off another ball), not because of its draw spin.

pj
chgo

 

[Andrew Manning]

I don't recall having had any acrimonious disputes with you but if I did post offensively to you, I apologize.

I don't recall any disputes between you and I, so no apologies necessary, I just don't like it when two members constantly bicker, because the discussions become about the history between the two posters instead of about the subject matter of the thread. I don't want to get involved enough in the matter to research the post histories, but the reason for my last post was that the last thread I saw where you and Patrick got into it, he was responding to somebody else's questions and you came in and made a personal attack out of the blue, turning the thread into a personal fight instead of a pool discussion.

Anyway, I agree with Wilson that you both need to quit using otherwise pleasant threads to air out your apparent dislike for each other. You got all the blame in my previous post, which is probably unfair since it takes two to have a prolonged fight, but it was because the last thread I read with the two of you in it, I thought you were the one most out of line.

I'm already regretting getting myself involved in this one, so if you'll accept my apology for unfairly placing all the blame on one side of the fight, I'll try and back away quietly.

-Andrew

 

[Bob Jewett]

Bob...I think you could learn something about these shots from Randyg. ...

Maybe. And Scott, I think you could learn something from the articles I've written about these techniques. They are available for free at www.sfbilliards.com. I've been playing close draw shots since I saw the great fancy shot artist Rene Vingerhoedt play them in exhibitions in 1966. We also filmed them during the Jacksonville Project and video clips from that are now available somewhere on azbtv.com but I can't find them right now.

 

[CaptainJR]

What is the shot called when you are hitting the bottom of the cue ball knowing that you are not hitting it hard enough to keep the reverse spin on it till it hits the object ball? You know, you hit draw and know the cue ball will be rolling forward when it hits the object ball? I know they have a name for it here but I can't think of it.

Anyway, l use this technique and I would be surprised if I wasn't decelerating at impact. It almost feels like I use the deceleration to gauge how hard I'm hitting it. Like the practice swings are at stop shot speed and then I slow down into the shot to produce this effect.

Probably not a good thing but works for me pretty good.

 

[Patrick Johnson]

What is the shot called when you are hitting the bottom of the cue ball knowing that you are not hitting it hard enough to keep the reverse spin on it till it hits the object ball?

Drag draw. I think of it like the CB is dragging a weight that slows it down.

[Decelerating stroke is] Probably not a good thing but works for me pretty good.

I don't think there's anything inherently wrong with a little deceleration - it's when there's lots of deceleration (like when the CB is really close to the OB) that your stroke can go goofy. Contrary to what lots of people believe, "accelerating through the CB" doesn't really happen and wouldn't add anything to CB action if it did. It's really a concept to keep your stroke smooth and straight up to the moment of contact, with no effect afterwards (except maybe to keep your followthrough straight).

pj
chgo

 

[av84fun]

Andrew

I'm already regretting getting myself involved in this one, so if you'll accept my apology for unfairly placing all the blame on one side of the fight, I'll try and back away quietly.

Gladly.

Regards,
Jim

 

[Patrick Johnson]

Maybe. And Scott, I think you could learn something from the articles I've written about these techniques. They are available for free at www.sfbilliards.com. I've been playing close draw shots since I saw the great fancy shot artist Rene Vingerhoedt play them in exhibitions in 1966. We also filmed them during the Jacksonville Project and video clips from that are now available somewhere on azbtv.com but I can't find them right now.

Yeah, but I bet Vingerhoedt didn't have cool names for his techniques like "pierce factor". That's a New School enhancement.

[Edit: Damn! Keep forgetting the smilies. --> ]

pj
chgo

 

[av84fun]

What is the shot called when you are hitting the bottom of the cue ball knowing that you are not hitting it hard enough to keep the reverse spin on it till it hits the object ball? You know, you hit draw and know the cue ball will be rolling forward when it hits the object ball? I know they have a name for it here but I can't think of it.

Anyway, l use this technique and I would be surprised if I wasn't decelerating at impact. It almost feels like I use the deceleration to gauge how hard I'm hitting it. Like the practice swings are at stop shot speed and then I slow down into the shot to produce this effect.

Probably not a good thing but works for me pretty good.

Right. The drag draw is an extremely valuable shot and one that should be practiced more than it likely is. Not only is the shot itself valuable, but it also is a great "in stroke" test because, given the nature of the shot, if you are not executing a pure stroke featuring very exactl tip-to-ball delivery then curve, squirt, throw will mess the shot up big time.

And while "accelerating through the ball" is subject to different definitions, Bob Jewett's Jacksonville Project showed that the cue does accelerate "through the ball" if you measure acceleration from the instant of CB contact.

Here is a quote from his article on that topic...

"A very interesting and unexpected feature
in the plot is that the cue speeds back up
after the ball has left. This turns out to be
from the hand and arm, which don't slow
down much during the very brief tip-ball
contact. After the ball has left, the cue, hand
and arm gradually go to their average
speed, which is about halfway between the
peak speed and the reduced cue speed after
contact."

So if "accelerate through the ball" is defined as continuous acceleration from before CB impact to after it...then no, that does not take place.

But if "through the ball" is defined as from the instant of contact and afterward...which IMHO is a more precise definition of the phrase... then acceleration does occur.

You might win a prop bet if you use the more precise definition.

Regards,
Jim

 

[Patrick Johnson]

if "through the ball" is defined as from the instant of contact and afterward...which IMHO is a more precise definition of the phrase... then acceleration does occur.

I mostly agree with this, but to be really precise, I think you'd have to say that re-acceleration occurs beginning some small amount of time after the instant of contact (and after the CB has left the tip). Contact with the CB is what slows the stick down (to about half its speed).

That may sound picky, but many players think "accelerating through the CB" makes the tip stay in contact with the CB longer and produces more CB action (spin). This isn't true, so these details have some practical meaning.

pj
chgo

 

[av84fun]

I mostly agree with this, but to be really precise, I think you'd have to say that re-acceleration occurs beginning some small amount of time after the instant of contact (and after the CB has left the tip). Contact with the CB is what slows the stick down (to about half its speed).

That may sound picky, but many players think "accelerating through the CB" makes the tip stay in contact with the CB longer and produces more CB action (spin). This isn't true, so these details have some practical meaning.

pj
chgo

I don't think your definition is more precise at all and was largely redundant to mine since mine too dealt the cue speed AFTER impact as in..."defined as FROM the instant of contact and afterward."

One of the definitions of the word "from" is as follows:

"2. (used to specify a starting point in an expression of limits): The number of stores will be increased from 25 to 30."

Clearly, the 25th store already exists so the starting point of the "expression of limits" is at a moment in time after its creation...just as my expression of limits was clearly after the instant of contact "and afterward."

So, for the sake of precision, there is only acceleration and then decelleration after contact and not re-acceleration...unless you turn to the alternate definition that I already proposed.

It is because I was separating the pre and post contact cue behaviors that I provided two different definitions. In the first, yes, "re-acceleration" is an appropriate enough term...but not in the second for the reason cited above.

I don't think my above comments are picky because I suggested a prop bet on that issue, the winning of which would require a very precise...and accurate definition.


Re:

but many players think "accelerating through the CB" makes the tip stay in contact with the CB longer and produces more CB action (spin). This isn't true, so these details have some practical meaning.

I don't know how many players may be holding to that belief but the millisecond of contact time has been widely known and extensively reported for some time so I doubt that there is much purpose in commenting further on that topic but certainly, such reminders can't hurt.

What I remain unclear on is whether and to what extent, tip hardness influcences the "millisecond" of contact time. Possibly, you have some data on that issue.

Jim

 

[Patrick Johnson]

av84fun:
One of the definitions of the word "from" is as follows:

I'm not interested in dueling dictionaries, so I'll just repeat my point:

The stick:

1. Accelerates up to (or maybe a little before) contact with the CB
2. Decelerates dramatically upon contact with the CB
3. Re-accelerates (but not fully) after the CB is gone.

This means there is no such thing as "accelerating through the CB" in the sense of a continuous, unbroken acceleration or, most importantly, in any sense that can directly affect CB action.

You'll have to email Bill Clinton to debate the definition of "from".

pj
chgo

 

[sde]

I'm not interested in dueling dictionaries, so I'll just repeat my point:

The stick:

1. Accelerates up to (or maybe a little before) contact with the CB
2. Decelerates dramatically upon contact with the CB
3. Re-accelerates (but not fully) after the CB is gone.

This means there is no such thing as "accelerating through the CB" in the sense of a continuous, unbroken acceleration or, most importantly, in any sense that can directly affect CB action.

You'll have to email Bill Clinton to debate the definition of "from".

pj
chgo

LOL...Great side step.

Rep coming your way

Steve

 

[av84fun]

LOL...Great side step.

Rep coming your way

Steve

You've got to be kidding! (-:

Sidestep?

He sidestepped into a bucket of objectionable material by obviously failing to understand the English language (which he "sidesteps" by his smart aleck response about not wanting to engage in dueling dictionaries) and then proves that he could not comprehend the SIMPLE to understand definitions I wrote which were...

" So if "accelerate through the ball" is defined as continuous acceleration from before CB impact to after it...then no, that does not take place."

But if "through the ball" is defined as from the instant of contact and afterward...which IMHO is a more precise definition of the phrase... then acceleration does occur.

He didn't even GET IT that in my first definition I WAS AGREEING WITH HIS POSITION about reacceleration which he PROVED by going to the entirely unnecessary trouble of rephrasing what I had already agreed to.

ROFLMAO!

But tell me, do you think the the cue "re-accelerates" if the starting point for the measurment is after the fact of CB impact?

(-: