prove me wrong

coopdeville said:
and so what of the trajectory?
which is the original topic of this discussion.
Click to expand...

The frictional force acts to spin the ball and also move the ball, and these two things come in exactly the same proportion over which you have no control. With dirtier balls, you'll get more spin and more throw, but in the same proportion.

Put a pencil down on a desk. Now flick the eraser sideways with your finger. You'll both spin the pencil and move the pencil. This is what either SIT and CIT (I don't really understand why a distinction is made between these) do to the object ball.
 
coopdeville said:
(snip)


does this SIT somehow change the contact point?
Click to expand...

I think this is the most important point about this concept so I'll crawl out on a limb and say, "Yes." Instructors have disagreed with me, but I've used this concept for years with a good degree of success. Maybe my mind is just tricking me, but based on the recent scientific trials, it seems to be true.

This means that the tangent line can be changed while still potting the ball, which can be very helpful in certain circumstances.

As for the proof of it all, Dave's videos are a great resource. Not the only source, but a great one to really see how it works. I wouldn't give up on Dave yet. You might get some of the last 12 months of Billiards Digest and peruse Dave's article there where he goes into this more.

fwiw,

Jeff Livingston
 
PKM said:
It's over my head, but if no one has linked it yet, here is Dr. Dave's technical proof
http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-14.pdf
Click to expand...


I haven't read his work, but have watched his videos,
which are flawed.

mike,
I don't think your analogy fits here.
we're talking about one spinning object contacting
one static object.

The spinning object also has velocity, this velocity is
transferred, as well as the spin (to some small degree).

Doesn't it make sense that since the spin on the CB doesn't
affect it's rebound angle, or tangent, then the OB's trajectory
will be affected by the spin in the same way?

none.

If there were significant friction between the two, shouldn't
both be affected similarly?

If it's not possible to pull the CB off of the tangent line using side
how is it possible that the OB will act otherwise?

Shouldn't it be easier to show some change in the tangent line w/ side
since we're imparting so much more onto the CB than the CB imparts
onto the OB?

Would this be known as OB deflection?

Is there a way to correct this OB deflection?

Wouldn't this OB deflection only be present in an off center hit(cut shot)
the same way that the CB is affected by striking it with the cue stick
off center?
 
coopdeville said:
I haven't read his work, but have watched his videos,
which are flawed.

If there were significant friction between the two, shouldn't
both be affected similarly?

If it's not possible to pull the CB off of the tangent line using side
how is it possible that the OB will act otherwise?
Click to expand...
You keep changing what you want to discuss, and completely disregard well reasoned responses with questions directed to you.

At this point, I can only assume you are trolling.

-td
 
coopdeville said:
I[...]

mike,
I don't think your analogy fits here.[...]
Click to expand...
it fits


Doesn't it make sense that since the spin on the CB doesn't
affect it's rebound angle, or tangent, then the OB's trajectory
will be affected by the spin in the same way?

none.
Click to expand...

It affects the cueball's speed in that tangent direction, and it affects the cueball's spin.
If there were significant friction between the two, shouldn't
both be affected similarly?
Click to expand...

Yes. They are.

If it's not possible to pull the CB off of the tangent line using side
how is it possible that the OB will act otherwise?
Click to expand...

The OB does not act otherwise. The effect of frictional force is sideways. It's only when this small sideways motion is added to the much more substantial forward motion of the OB (which is the result of a different force) that what we see just a slightly modified direction for the OB

Shouldn't it be easier to show some change in the tangent line w/ side
since we're imparting so much more onto the CB than the CB imparts
onto the OB?

Would this be known as OB deflection?

Is there a way to correct this OB deflection?

Wouldn't this OB deflection only be present in an off center hit(cut shot)
the same way that the CB is affected by striking it with the cue stick
off center?
Click to expand...

I don't know what you're talking about here.
 
I must be more confused than I thought

I'm pretty sure I've been talking about the effects of a
spinning cue ball contacting a stationary object ball the whole time.

There is clearly a difference in OB reaction when there is a cut angle
as opposed to a center ball hit but I don't think that difference is
relative to the spin.

I really don't think that spin can change the angle of the shot even 1*.

Unfortunately, this discussion has digressed.

Thanks to everyone who participated.

fwiw, usually when I hear "I had to throw it"
this person is walking back to their chair.
 
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This may be a record!

Having read every post in the thread, and speaking from my admittedly limited experience, I think this thread may have set an all-time record for the ratio of good information+good intentions divided by the amount of improved understanding on the part of the original poster! But wait, just a moment of reflection reveals that there has been NO improvement in the original poster's understanding, so that means we have a ratio with a zero in the denominator, and that, unfortunately, is an operation that is simply not allowed in mathmematics. I'm not sure what to make of all the people who tried to be helpful when it seemed to me from early on that the original poster was essentially saying, "I'll bet you can't prove me wrong!" Now did anyone expect they would ever see the original poster make a post saying that he had to admit he was wrong??? For what it's worth, in my view, one value of this thread is to serve as evidence that the compulsive need to be right is one of the greatest impediments to getting along with one another. And I know I'm right about this!:D :D :D
 
coopdeville said:
I'm pretty sure I've been talking about the effects of a
spinning cue ball contacting a stationary object ball the whole time.

There is clearly a difference in OB reaction when there is a cut angle
as opposed to a center ball hit but I don't think that difference is
relative to the spin.

I really don't think that spin can change the angle of the shot even 1*.

Unfortunately, this discussion has digressed.

Thanks to everyone who participated.

fwiw, usually when I hear "I had to throw it"
this person is walking back to their chair.
Click to expand...

I completely forgot that Colin Colenso did a throw test too:
http://youtube.com/watch?v=D-xtzn4vbiQ

With every shot, the contact point is the same (he starts with the balls frozen). You can see how various cue ball spins affect the object ball. If you still don't accept that cue ball spin can throw the object ball, I'm not sure what can.
 
Scenario 1:

The throw will be very noticable if you let the object ball rebound from a rail. For example, set up your favorite bank and slam it hard...then slam it with inside. You'll be supprised how short you can come. The opposite is true with outside. In one pocket you have to adjust for this to play position and shoot toward your hole...

Oh, and no, the object ball is not going to curve or masse...the cueball will, but the object ball will not get enough transfered to it.
 
fred_in_hoboken said:
I completely forgot that Colin Colenso did a throw test too:
http://youtube.com/watch?v=D-xtzn4vbiQ

With every shot, the contact point is the same (he starts with the balls frozen). You can see how various cue ball spins affect the object ball. If you still don't accept that cue ball spin can throw the object ball, I'm not sure what can.
Click to expand...

this is interesting, the speed of the CB and the cut angle seem
to influence the "throw" more than the spin does.

and balls frozen together clearly react differently than when one ball is
in motion and contacts a stationary ball.


Bill,

If the ratio of "good" information is equal to my existing information
how do I improve my understanding?

Thanks for all of your insight :rolleyes:
 
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BillPorter said:
For what it's worth, in my view, one value of this thread is to serve as evidence that the compulsive need to be right is one of the greatest impediments to getting along with one another. And I know I'm right about this!:D :D :D
Click to expand...
+1 Bill. Oh, I like your new avatar.

-td
 
coopdeville said:
influence the "throw" more than the spin does.
Click to expand...

You (again) conceded that spin influences a shot (i.e., something influencing throw more than spin means inherently that spin influences throw). Ok, it's been proven and you admit it.

I know there are plenty of technically minded folks here that can shed light on various issues. Can you please reformulate your discussion point so we can all be on the same page?

-td
 
and

seymore15074 said:
Scenario 1:

The throw will be very noticable if you let the object ball rebound from a rail. For example, set up your favorite bank and slam it hard...then slam it with inside. You'll be supprised how short you can come. The opposite is true with outside. In one pocket you have to adjust for this to play position and shoot toward your hole...

Oh, and no, the object ball is not going to curve or masse...the cueball will, but the object ball will not get enough transfered to it.
Click to expand...

From what I've seen, the OB will not receive enough spin to be visible
and if the object ball is visibly rolling, and not spinning, how do you account
for this smaller angle from the rail.
I think you're hitting it harder or with a cut angle.

They made an OB masse in Poolhall Junkies. :p
 
BillPorter said:
.... one value of this thread is to serve as evidence that the compulsive need to be right is one of the greatest impediments to getting along with one another. And I know I'm right about this!:D :D :D
Click to expand...

And for a change I agree :)

Dave .... must ... keep ... mind ... open
 
Ouch

td873 said:
You (again) conceded that spin influences a shot (i.e., something influencing throw more than spin means inherently that spin influences throw). Ok, it's been proven and you admit it.

I know there are plenty of technically minded folks here that can shed light on various issues. Can you please reformulate your discussion point so we can all be on the same page?

-td
Click to expand...

the effect of spin transfer is negligible and I still don't see any reason
to believe that the SPIN on a cue ball that contacts point A on the OB
causes the OB to leave the collision in any direction other than exactly
opposite point A.

If it's in this thread, I missed it, maybe someone will be kind enough
to reiterate.

As I've already made painfully evident, I'm not that bright.
You guys don't have to rub it in.
 
coopdeville said:
the effect of spin transfer is negligible and I still don't see any reason
to believe that the SPIN on a cue ball that contacts point A on the OB
causes the OB to leave the collision in any direction other than exactly
opposite point A.

If it's in this thread, I missed it, maybe someone will be kind enough
to reiterate.

As I've already made painfully evident, I'm not that bright.
You guys don't have to rub it in.
Click to expand...
This has been the most useless thread, mainly because you seem to be unable to let new information in. It's not about being bright. It's about mental filters. You've been given several ways to test that which everybody else already knows to be true. Just conduct the tests and prove it to yourself. There is no reason for you to believe things, but it is important that you open your mind enough to try things. Other people have given you guidance and it is up to you to experiment.
 
coopdeville said:
the effect of spin transfer is negligible and I still don't see any reason
to believe that the SPIN on a cue ball that contacts point A on the OB
causes the OB to leave the collision in any direction other than exactly
opposite point A.

If it's in this thread, I missed it, maybe someone will be kind enough
to reiterate.

As I've already made painfully evident, I'm not that bright.
You guys don't have to rub it in.
Click to expand...
1st - the ball doesn't leave "exactly opposite point A" on the majority of shots in pool anyway. Thus, your starting point is flawed to begin with. Read Kohler's Science of Pocket Billiards for experimental data proving this. Dr. Dave also has created relevant info.

2nd - Re-read post 62. It shows a simply way you can prove this to yourself. I'll repost the relevant portion here for your viewing pleasure.


Jack Kohler published a very thorough description regarding this back in the late 80's. Using mechanical devices for repeatability (i.e., no human error), he calculated various throw angles based on english enduced throw for all cut angels from 0 to 90°. If you review his efforts, and have any comments, please post them. At that point we should be on the same page to have an informed discussion.

Lastly, here is a shot that Jack uses to illustrate the existence of EIT throw.

CueTable Help



Set the shot up so that the 1 cannot be made with a center ball hit. As shown. When applying outside english, the 1 goes in. Thus, there is english enduced throw.

Please set this up yourself - using hole punch reinforcement circles to mark the balls. After you confirm this for yourself, please let me know if this needs additional discussion.


-td
 
oh well

Rarelymisses said:
This has been the most useless thread, mainly because you seem to be unable to let new information in. It's not about being bright. It's about mental filters. You've been given several ways to test that which everybody else already knows to be true. Just conduct the tests and prove it to yourself. There is no reason for you to believe things, but it is important that you open your mind enough to try things. Other people have given you guidance and it is up to you to experiment.
Click to expand...

You really assume a lot here, Rarelymisses.

I'm going to have to do my own study.

Colin's video has holes in it too.

I was looking for indisputable evidence and it clearly doesn't
exist in this forum.

If I can't find it, I'll make it, for all of you.
cheers,
-coop
 
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