prove me wrong

[gregory]

since this shot is supposed to be a dead full hit on the OB.
shouldn't the cue ball stop and not follow the tangent of a cut shot?

and shouldn't the OB be spinning?

I'll not discuss Dr. Dave's works further.

Who cares what you'll discuss. You are obviously clueless or a troll. Dr Dave sets up the balls so that it is impossible to do a cut shot. There is a ball between the cue ball and the OB that blocks the CB from cutting the OB. But I can see how you may have missed that part since it is only the entire first 2/3 of the video.

Of course the CB moves in the opposite direction of OB. Since cut shot is obviously impossible with the blocking ball in the way, perhaps there is some other way this happens. Magic? Probably. But also an outside chance that it simple physics. Equal and opposite reaction. If OB is thrown in one direction by the contact, CB must be thrown in the other.

Anyway, since seeing throw doesn't convince you it works, and mathematical proff doesn't convince you either, please explain what sort of proof you need to convince you and maybe we can help.

 

[sde]

After reading this thread, I believe that all the nice people who made sincere efforts to help this fellow understand that throw does exist and is an essential technique for playing pool at anything above a banger level have made their efforts in vain. Any impartial reader of this thread can see that the original poster will never accept any evidence or argument regarding throw. It is almost impossible to believe that his intention in starting this thread was a sincere desire to learn anything whatsoever. Or I suppose it is possible that he simply can't understand.

Well said Bill, thanks for saving me the effort.

Steve

 

[Ballistic Billiards]

tangents, I do understand.

Who cares what you'll discuss. You are obviously clueless or a troll. Dr Dave sets up the balls so that it is impossible to do a cut shot. There is a ball between the cue ball and the OB that blocks the CB from cutting the OB. But I can see how you may have missed that part since it is only the entire first 2/3 of the video.

Of course the CB moves in the opposite direction of OB. Since cut shot is obviously impossible with the blocking ball in the way, perhaps there is some other way this happens. Magic? Probably. But also an outside chance that it simple physics. Equal and opposite reaction. If OB is thrown in one direction by the contact, CB must be thrown in the other.

Anyway, since seeing throw doesn't convince you it works, and mathematical proff doesn't convince you either, please explain what sort of proof you need to convince you and maybe we can help.

my small brain doesn't comprehend tangent lines on perfectly straight
shots.
The only physically possible reaction is a follow or draw.
please tell me why the OB isn't spinning at a similar rate
to the CB. I'm dying to know.

 

[gregory]

my small brain doesn't comprehend

QFT!!!!!!!!!

 

[Ballistic Billiards]

what I've learned from Dr. Dave.

QFT!!!!!!!!!

1. that you can't transfer a visible amount of spin to an ob.

2. you can create a cut angle where there isn't one.



does this SIT somehow change the contact point?

 

[John Barton]

since this shot is supposed to be a dead full hit on the OB.
shouldn't the cue ball stop and not follow the tangent of a cut shot?

and shouldn't the OB be spinning?

I'll not discuss Dr. Dave's works further.

I think you shoudn't discuss them as it's hrd to refute proof like that. Throw is also not about masse or startting in one direction and moving in another.

Throw is about pushing the object ball into a new line BEFORE it moves forward. This is clearly seen on the frozen ball throw shots. It happens with a cueball and object ball shot because the cuball acts as a gear and pushes the object ball off the line of contact into a different angle.

So for example:

If the path to the pocket was slightly blocked by another ball. It is often possible to throw the object ball slightly to the side before it begins it's forward journey. That slight movement is often enough to clear the blocking ball.

And of course my other example still applies where you throw a ball in for position's sake because the cut angle would put you out of position.

This is what people mean when they say they had to throw the ball in.

Dr. Dave's illustration via video is 100% accurate and is completely indicative of what happens when a ball is thrown in.

As for making an object ball masse' ........... I'd like to see that too - I am betting on Semih Sayginer, Mike Massey, or Jamison Neu to make that happen someday. Bit that won't be throw - it will be magic.

 

[Ballistic Billiards]

this i can understand

I think you shoudn't discuss them as it's hrd to refute proof like that. Throw is also not about masse or startting in one direction and moving in another.

Throw is about pushing the object ball into a new line BEFORE it moves forward. This is clearly seen on the frozen ball throw shots. It happens with a cueball and object ball shot because the cuball acts as a gear and pushes the object ball off the line of contact into a different angle.

So for example:

If the path to the pocket was slightly blocked by another ball. It is often possible to throw the object ball slightly to the side before it begins it's forward journey. That slight movement is often enough to clear the blocking ball.

this is contact induced throw, not spin induced throw.
IMO, you can't use CIT on a dead straight shot, only on a cut shot.


SIT implies that spin transferred from the CB to OB
will change the intended trajectory of the OB.

thanks for all the replies, relevant or not.
I'm still wondering why Dr. Dave is the only
one to video document these principles.


I've still seen no evidence of SIT.

 

[Ballistic Billiards]

I'll work on this one

CueTable Help

I'm going to try this
and invite anyone else to do so as well
don't touch the 3 or the 7 and pocket the 4 .
you'll have to adjust your aim to account for the squirt caused by the extreme spin
and the 4 should spin to the right...
yeah, that makes sense

 

[td873]

I'm of the belief that you can't transfer enough spin, on a clean
set of balls, to make a significant change to the trajectory of the OB.

Someone here can surely convince me that I'm wrong.

It is well known and documented that SIT exists. Try a search, as this has been discussed for years. IIRC, even Dr. Dave has a high speed video showing that SIT exists.

Lastly, your premise is filled with qualifiers that make it hard to "prove you wrong" or "convince you." Such as "transfer enough spin" "clean set of balls" "significant change." Each time someone tries to illustrate some effect, it's easy to modify the parameters to show that "that wasn't enough spin" or "that change wasn't significant" etc.

This effect is well documented, understood, experienced, and discussed. Just because you don't believe it exists, doesn't mean it isn't so.

-td

 

[mikepage]

my small brain doesn't comprehend tangent lines on perfectly straight
shots.[]

I'm pretty sure you're "joking." I'm done.

 

[Ballistic Billiards]

pro side

Interesting that because I challenge a "well known" pool theory
I'm a nit and a banger, etc.


As I'm considering one man's validity and whose I'd be most comfortable
with, I realize that the most highly regarded of the bunch will advise
everyone to not adopt these practices.

For anyone that claims this is a simple pyhsics equation,
I'd like to put this equation into practice.
How do I deduct the variables and leave myself with something
practical to use at the table for an SIT, the same as I use simple geometry.

I'm going to build something

 

[Neil]

..................

 

[Ballistic Billiards]

Here's a little experiment I just did on my table. I put two boards parellel to each other to where the cueball fit snug, but not too tight between them. They were about two and a half feet long. hen I put an object ball about half an inch from the end of the boards, but still inside them. I shot with no english and marked where the ob hit the rail. Then I did it with extreme left and right english. Withinin the three feet to the rail, the english shots changed where the ob hit the rail by about two and a half inches.

To my thinking, this is not collision induced throw, because the ob still had to go thru the boards initially. Take it for what it's worth.

good test
I'm going to do something similar

was it possible that the OB clipped the end of either board?

 

[Neil]

.............

 

[third_i]

you see... on Earth there is this thing call friction. And when two objects come together the friction between the two transfers energy as well as the sheer force of the contact. So when a ball is spinning and another ball is contacted by this spinning ball the result between the contact of the two balls is going to do three things:
1) The OB will move, the force from it being hit will cause it to move away from the direction in which the CB contacted it.
2) The spin of the CB will transfer to the OB at a largely decreased amount.
3) The lost energy from the contacting/spinning cue ball is going to force the OB slightly to the opposite direction of the spin.

I find that it is more visual and apparent with a medium hit.

Also, you can masse by putting a lot of english without jacking up on the cue ball... BUT it won't curve a lot, it will go about a 1/4 of a ball maybe a little more, on a shot along the length of the (9')table. Balls spinning fastly rarely roll straight because the ball needs to be rolling on a perfectly flat surface with perfect side spin. Any leftover chalk or various debris might cause that ball to rock slightly allowing the spin to catch, but more often than not it will be the stroke from the shooter hitting down on the cue ball slightly.

 

[Franky]

Lets play some one pocket fisheee!!

Seriously though, collision versus spin induced throw are just relative to your frame of reference. Simply put, throw exists. Transfer of spin exists. Collisions are not instantaneous, they take a finite amount of time to occur. Friction exists. We are not in a vacuum.

You could do with some schooling on topics such as impulse, static friction, dynamic friction, conservation of momentum and elastic versus inelastic collisions to start with. For this I suggest a course in calculus-based Newtonian physics at your local CC. You'd probably have fun with it. I not afraid to admit that I did in school.

I don't think you need to go into the more detailed physics describing collisions between rotating spheres to gain a logical understanding of the answer to your question.

 

[td873]

the 4 should spin to the right...

This is another false premise, and flawed experiment from the design.

It's trivial to prove your point when you make it impossible to contradict you.

-td

 

[td873]

People are always talking about throwing balls with spin (SIT - spin induced throw)

I can throw it more this way or I had to throw it in, etc.

I'm of the belief that you can't transfer enough spin, on a clean
set of balls, to make a significant change to the trajectory of the OB.

Someone here can surely convince me that I'm wrong.

Please clarify the following to actually make progress in your discussion:

What do you mean by "significant change"? Is this measured in angels? If so, how much is "significant to you"? 10°, 5°, 1°?
What is a "clean set of balls"? Brand new? Some play? Typically used at a pool hall?
What do you mean by "transfer [..] spin"? Imparting spin to the object ball?
What do you mean by "change to the trajectory" of the OB? A change only on a head-on hit? A change in trajectory on an oblique shot (obtuse angle? actute angle?)?

If we have a working set of parameters, we can move forward in the discussion. But I think people are becoming uninspired when they have to hit a moving target.

Thanks,

-td
What do you

 

[td873]

since this shot is supposed to be a dead full hit on the OB.
shouldn't the cue ball stop and not follow the tangent of a cut shot?

Why should it? There is spin involved, right? So if one ball moves one way, the other MUST move the other way [Newton (3)]? Or is Netwon wrong?

-td

 

[Jal]

Interesting that because I challenge a "well known" pool theory
I'm a nit and a banger, etc.

You're not a nit for challenging a theory. Some of the stuff propagated by pool instructors, pros and "physics" people does turn out to be wrong. But you seem to be fixed on the idea that the spin put on the OB (if any) is the cause of the throw. Several posters have pointed out that this is not the case, but you persist. Until you rid yourself of this notion, you'll continue to struggle with the concept.

Spin induced throw (SIT) means throw resulting from spin on the cueball, not the object ball. If the OB is thrown, it will inevitably acquire spin while being thrown (during impact). But this spin will only cause it to masse very slightly according to my understanding. As everyone has been saying, it's the friction between the balls while they are in contact that does the deed.

It might help if you chuck the ideas of CIT and SIT aside. Think in terms of relative surface velocity between the points of contact of the two balls. This can be due to cut angle and/or spin on the cueball. During impact, friction acts to reduce this surface velocity (to zero in many cases). In other words, it undergoes a change.

The object ball always acquires 1/7'th of this change in surface speed as linear velocity, and 5/14'ths of it as spin (the product of its radius R X its spin rate W is equal to 5/14'ths of the change in surface speed). Its acquired linear speed is in the direction of the initial surface velocity between the contact points, which may be up/down, sideways, or anything in between. Only the sideways component is important as far as shotmaking is concerned.

But the point is that all this happens during impact, and that the spin it picks up is not a cause of throw. You might call it a side effect.

Jim