# Physics-Minded..How does the CB know?

#### Patrick Johnson

##### Fish of the Day
Silver Member
If what you decribed of the CB "pushing" the shaft away from it is what was occurring, then high speed video should show the "pushing away" as happening "during" contact instead of after contact.

Me:
That's what it shows.

Me earlier:
... For instance, much of the sideways deflection of the shaft happens after the cue ball is gone - you can see this in high speed videos.

Patrick you should really make up your mind which one it is. Either the deflection is shown to be during contact or after contact. You can't have it both ways depending on what you're arguing for or against.

Jaden, you should really read more carefully. Shaft deflection "happens" both during and after contact with the ball, but the ball is "pushing" the shaft only during contact (of course).

pj
chgo

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#### bagofpaper

##### AzB Silver Member
Silver Member
bluepepper said:
1)Say you're the cue ball. You're struck at the same speed and contact point by the same modern low-squirt shaft placed on two different butts. The first contact is from a 17 oz. total weight cue. The second contact is from a 25 oz. total weight cue. How do you know to react differently?

For an off-center contact point, and different overall masses with same velocity at impact with transfer different amounts of angular momentum to the cue ball. That is assuming same contact point, same tip material (i.e. same coef. of friction and the same coef. of restitution (this is the fractional amount of energy loss in a collision). The heavier cue will give the cb more angular momentum after contact.

bluepepper said:
2)Same scenario, but the 17 oz. cue is being held with a death grip, and the 25 oz. cue is being held with a feather touch that allows the cue to be thrown into the cueball. Still both cues contacting the cueball at the same speed. How does this change things? Does the arm's mass with the 17 oz. shot come into play, in essence, fusing with the cue's mass?

The grip will complicate things if you want to understand this from a physics perspective (i.e. quantitatively). Everything stripped down to it's essentials you have two bodies, the cue and the cue ball, coming into contact. If you include the possibility of a jerky stroke it can get very complicated to say the least.

bluepepper said:
3)How about 2 cues with the same shaft and overall weight but the first has most of its weight forward, the second has most of its weight rearward?

I'm don't know the arguments for why less end mass on the cue shaft reduces deflection... Is this an empirical result? If the elasticity of the cue and cue ball need to be accounted for in this problem, I'd say you would need a finite element type of simulation to look at the dynamics.

I do know that if you do a very simple experiment to measure the coef. of restitution of say a ball colliding with a wall you would measure a distribution of coefficients. Which tells you there is some form of randomness to the response of a ball hitting a wall. The experiments I'm referring to involve steel beads roughly 1 cm is diameter colliding with a large steel plate under gravity. These are the same length scales as in pool or billiards. I'd guess that you'd see similar results on phenolic pool balls as well.

If the flexibility of the shaft is an issue, and analytical answer looks impossible, but then again I'm not a Russian physicist..

bluepepper said:
4)How about 2 cues with the same shaft and overall weight but the first has most of its weight around the perimeter, the second has most of its weight in its core?

Uhm, this is also complicated for the same reasons stated above.

Thanks,
Jeff[/QUOTE]

#### Patrick Johnson

##### Fish of the Day
Silver Member

...the endmass of the cue will be a direct correlation to the amount of compression because of the differing masses of the interrelating masses...

...If the mass of the end of the shaft is greater then it will have a greater amount of affect on the mass of the CB and the tip or shaft will compress more

Can you elaborate on this idea some more? I don't get how you think greater end mass = more compression.

pj
chgo

#### bagofpaper

##### AzB Silver Member
Silver Member
This reminds me of scientists initially creating the ether after the discovery of lightwaves and then switching to particles behaving as waves, when they were closer to the truth the first time. The thing that led them astray was the belief that they had to create an undiscovered medium for the waves to travel on, when they already had space/time. radiowaves travel on speac.time itself, and while I can't prove this as of yet, as Bob already stated and anyone who knows of Descartes' philosophy should know that only that you exist can be proven. In science hypotheses can only be disproven or rather, a better hypothesis that explains phenomena better can be introduced.

Radiowaves or any form of electromagnetic radiation have no medium through which they propagate. Michelson and Morley in 1887 proved experimentally there is no "ether". Maxwell's equations (the equations of electrodynamics) show that there should be electromagnetic waves in free space. You can show this in two minutes of calculation. Not sure what you mean by "they were closer to the truth the first time." Physicists for over a hundred years have thrown out the possibility of "ether" simply because empirically it doesn't exist.

http://en.wikipedia.org/wiki/Michelson-Morley_experiment

We don't refer to Descartes' doubt everything except "I think therefore I am" philosophy when trying to understand natural phenomena. There are other philosophers, many who do not subscribe Descartes' philosophy, does this have any bearing on the explanation of radio waves? Uhm, no.

If you are a scientist, then you do believe that theories can be proven true not just dis-proven, or why would anyone bother to devote their lives to coming up with theories. This is actually a very important and interesting philosophical question (philosophers would call this the philosophy of science) and you are referring to the old philosophy of science called demarcation due to Karl Popper. My point is what constitutes a truly true theory is an a very open question.. people have been arguing over it for quite awhile and will continue to do so.

A philosopher can't answer the question of say if you take a car and start stripping parts off and replacing them with the same parts but physically different ones at some point you would say this is a different car even though it looks the same, drives the same, you still have a sense that the car is a different one. Say you replaced all the parts.. it would have to be a different car. If you only change one screw, you have the sense that it's the same car. At what point does it become a "different" car?

In light of all of that, like I said physicists know with 100% certainty there is no such thing as "ether". Ether being the medium of electromagnetic waves in the same sense that water or fluid would be the medium of waves on the sea. We did the experiment in 1887, we can do it today, in fact I'm sure there are modern and more accurate versions of this experiment and at no time did any physicist say oh wait maybe we were right..

Anyhow, lecture over...

#### bagofpaper

##### AzB Silver Member
Silver Member
Andrew Manning said:
I'm not Patrick, but: the impulse that sets the end of the cue in motion laterally happens during contact. After contact, the cue continues to deflect further due to the lateral momentum it gained during contact. Because contact is so short, I think most of the cue's lateral movement takes place after contact is over, but I'm certain all of it is due to the lateral momentum imparted on it during contact.

Also during contact, while these momentum transfers are taking place, a lateral momentum equal and opposite to the one that causes the cue to deflect is imparted on the ball. This is the lateral momentum we call squirt.

Does that clear things up?

-Andrew

Ok, I think this is great qualitative explanation.. and I believe there is truth to Andrew's bit here. As I said above, the detailed dynamics will depend on the elasticity of the materials involved. The shaft is bending and deforming while and after contact. Maybe less mass correlates with more flexible shaft? I'm not so sure.

What about density? Some woods are harder than others... presumably the first order effect on say the bending modulus would be the density.

#### Bob Jewett

##### AZB Osmium Member
Gold Member
Silver Member
bagofpaper said:
... I'm don't know the arguments for why less end mass on the cue shaft reduces deflection... Is this an empirical result? ...
This is both a theoretical and experimental result. It is also supported by the high-speed videos made in the Jacksonville Project and by Dave Alciatore. A good technical discussion is by Ron Shepard at http://www.sfbilliards.com/Shepard_squirt.pdf All of the video from the Jacksonville Project is now on www.AZBTV.com under the "Technical" thumbnail. Many of Dave Alciatore's high-speed videos and articles are on his web site: http://billiards.colostate.edu/

#### CueAndMe

##### AzB Silver Member
Silver Member
Bob Jewett said:
All of the video from the Jacksonville Project is now on www.AZBTV.com

In many of the off-center hits it appears that the cue tip is deflecting before any motion of the cueball takes place at all. Bad chalking or minor miscuing maybe? But to me it doesn't appear that the cueball spin is causing the deflection, just its presence.

Jeff

#### Bob Jewett

##### AZB Osmium Member
Gold Member
Silver Member
bluepepper said:
In many of the off-center hits it appears that the cue tip is deflecting before any motion of the cueball takes place at all. Bad chalking or minor miscuing maybe? But to me it doesn't appear that the cueball spin is causing the deflection, just its presence.

Jeff
If the cue tip does not slip on the cue ball during contact, and the cue ball acquires spin during the hit (as with any off-center contact) then the surface of the cue ball where the tip hits it must be moving partly to the side. Once these obvious facts are pointed out, they are obvious, but they eluded those who wondered about squirt for a long time. If the cue ball's surface moves to the side and the tip is not slipping on the cue ball's surface, the tip must be moving to the side during the hit.

I think that there were no minor miscues or not many. It is sometimes hard to see when the cue ball actually starts to move. In general, the cue ball will move less than 1/4 inch while the tip is on it. Also the tip will continue to move to the side after the cue ball has left because there is no force to bring it back immediately.

If you are really interested in the physical details of squirt, please read Ron Shepard's paper. Even if you don't understand all of it, it should partly bring you up to speed on the major points.

#### CueAndMe

##### AzB Silver Member
Silver Member
Bob Jewett said:
If the cue tip does not slip on the cue ball during contact, and the cue ball acquires spin during the hit (as with any off-center contact) then the surface of the cue ball where the tip hits it must be moving partly to the side. Once these obvious facts are pointed out, they are obvious, but they eluded those who wondered about squirt for a long time. If the cue ball's surface moves to the side and the tip is not slipping on the cue ball's surface, the tip must be moving to the side during the hit.

I think that there were no minor miscues or not many. It is sometimes hard to see when the cue ball actually starts to move. In general, the cue ball will move less than 1/4 inch while the tip is on it. Also the tip will continue to move to the side after the cue ball has left because there is no force to bring it back immediately.

If you are really interested in the physical details of squirt, please read Ron Shepard's paper. Even if you don't understand all of it, it should partly bring you up to speed on the major points.

I just skimmed Ron Shepard's paper. Just too much technical stuff for me to take in. Formulas throw me. But I'll accept that you guys know what you're saying. From your post, I'm picturing 2 gears meshing during contact.
Just a hypothetical... what would happen if the cue, rather than being held, was sent alone into the cueball by sliding it over a slippery surface like a block of ice? Will the cueball react the same?
You really don't have to answer this. I'm about exhausted and you've done enough. Let's just play pool.

Jeff

#### Patrick Johnson

##### Fish of the Day
Silver Member
...what would happen if the cue, rather than being held, was sent alone into the cueball by sliding it over a slippery surface like a block of ice? Will the cueball react the same?

Or hung it from strings and just let it swing (hmm). I predict that the cue ball would react the same way, but the stick wouldn't.

You really don't have to answer this.

Just when it's gettin' good?

pj
chgo

#### Bob Jewett

##### AZB Osmium Member
Gold Member
Silver Member
bluepepper said:
... Just a hypothetical... what would happen if the cue, rather than being held, was sent alone into the cueball by sliding it over a slippery surface like a block of ice? Will the cueball react the same? ...
Yes. As I've tried to say above, the flesh of the hands is too soft to allow them to get involved during the actual contact time.

#### CueAndMe

##### AzB Silver Member
Silver Member
Bob Jewett said:
Yes. As I've tried to say above, the flesh of the hands is too soft to allow them to get involved during the actual contact time.

Oh, I forgot. Sorry.
Jeff

##### "no buds chill"
Silver Member
This could go on forever, because you are obviously hopelessly stuck in paradigms.

bagofpaper said:
Radiowaves or any form of electromagnetic radiation have no medium through which they propagate. Michelson and Morley in 1887 proved experimentally there is no "ether". Maxwell's equations (the equations of electrodynamics) show that there should be electromagnetic waves in free space. You can show this in two minutes of calculation. Not sure what you mean by "they were closer to the truth the first time." Physicists for over a hundred years have thrown out the possibility of "ether" simply because empirically it doesn't exist.

http://en.wikipedia.org/wiki/Michelson-Morley_experiment

We don't refer to Descartes' doubt everything except "I think therefore I am" philosophy when trying to understand natural phenomena. There are other philosophers, many who do not subscribe Descartes' philosophy, does this have any bearing on the explanation of radio waves? Uhm, no.

If you are a scientist, then you do believe that theories can be proven true not just dis-proven, or why would anyone bother to devote their lives to coming up with theories. This is actually a very important and interesting philosophical question (philosophers would call this the philosophy of science) and you are referring to the old philosophy of science called demarcation due to Karl Popper. My point is what constitutes a truly true theory is an a very open question.. people have been arguing over it for quite awhile and will continue to do so.

A philosopher can't answer the question of say if you take a car and start stripping parts off and replacing them with the same parts but physically different ones at some point you would say this is a different car even though it looks the same, drives the same, you still have a sense that the car is a different one. Say you replaced all the parts.. it would have to be a different car. If you only change one screw, you have the sense that it's the same car. At what point does it become a "different" car?

In light of all of that, like I said physicists know with 100% certainty there is no such thing as "ether". Ether being the medium of electromagnetic waves in the same sense that water or fluid would be the medium of waves on the sea. We did the experiment in 1887, we can do it today, in fact I'm sure there are modern and more accurate versions of this experiment and at no time did any physicist say oh wait maybe we were right..

Anyhow, lecture over...

It is absolute folly to believe that all things that are observed in nature regarding waves are not true with radio waves. They MUST have a medium to travel through. They travel through the mdium of space/time. That is what I am saying. I'm sooo tired of people saying "we've done the experiments so THERE....." What experiments? It is possible that they were done incorrectly or misinterpreted.

That's like saying that the atomic clock experiments prove Einstein's theories of realtivity. BULL\$IT!!!!!. All the atomic clocks experiments prove is that an atomic clock up in the sky does not coincide with one that is close to the earth even though they started out the same. IT can be INFERRED that this MAY mean that time fluctuates close to a gravity source, but it is actually MORE likely that it infers that a gravity source affects the rate of fluctuation or frequency modulation of the atoms in whatever material is used for the atomic clocks.

This example is one of many where "PSeduo" modern science has claimed that an experiment proved something when it did NO SUCH THING. and the actual experimenters will usually admit, "to anyone that knows anything or chooses to think for themself" that it is not a proof but just evidence in support of something. IF you TRULY believe that anything cna be proven and not just supported, then it is YOU my friend, not I that is not a ture scientist.

I'm done with this thread.....

I was just about to admit that I may have been wrong about this idea, before this guy spouted off. After the post about the ball hitting the wall, I was able to picture a ball that was moving hitting a stationary cue tip and ther I am able to see how the CB would push the cue sideways. This also helps to picture how end mass would affect the amount of squirt. If there is more endmass then it would become more difficult for the CB to push the tip sideways and would have a greater affect on the diversion of the initial path.

I will not post any more in this thread though because closed mindedness pisses me off too much, especially those hopelessly stuck in the paradigms of the times, when in ten years much of what is believed to be proven now, will be disproven. It is a F#king joke.

Sorry for the rant, there is just nothing that pisses me off more than stupidity and lack of self actualized thought. I have an IQ on par with Stephen Hawking at 152 and to see people not able or more likely not willing to think for themselves at ALL is just frustrating.......

OOHOHHHHGGGGGGHHHHHH!!!!!!!!!!

#### Patrick Johnson

##### Fish of the Day
Silver Member
I have an IQ on par with Stephen Hawking at 152

That's not a very smart thing to say.

...and to see people not able or more likely not willing to think for themselves at ALL is just frustrating...

I think you mean "not willing to think like me".

pj
chgo

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#### jsp

##### AzB Silver Member
Silver Member
It is absolute folly to believe that all things that are observed in nature regarding waves are not true with radio waves. They MUST have a medium to travel through. They travel through the mdium of space/time. That is what I am saying. I'm sooo tired of people saying "we've done the experiments so THERE....." What experiments? It is possible that they were done incorrectly or misinterpreted.

That's like saying that the atomic clock experiments prove Einstein's theories of realtivity. BULL\$IT!!!!!. All the atomic clocks experiments prove is that an atomic clock up in the sky does not coincide with one that is close to the earth even though they started out the same. IT can be INFERRED that this MAY mean that time fluctuates close to a gravity source, but it is actually MORE likely that it infers that a gravity source affects the rate of fluctuation or frequency modulation of the atoms in whatever material is used for the atomic clocks.

This example is one of many where "PSeduo" modern science has claimed that an experiment proved something when it did NO SUCH THING. and the actual experimenters will usually admit, "to anyone that knows anything or chooses to think for themself" that it is not a proof but just evidence in support of something. IF you TRULY believe that anything cna be proven and not just supported, then it is YOU my friend, not I that is not a ture scientist.

I'm done with this thread.....

I was just about to admit that I may have been wrong about this idea, before this guy spouted off. After the post about the ball hitting the wall, I was able to picture a ball that was moving hitting a stationary cue tip and ther I am able to see how the CB would push the cue sideways. This also helps to picture how end mass would affect the amount of squirt. If there is more endmass then it would become more difficult for the CB to push the tip sideways and would have a greater affect on the diversion of the initial path.

I will not post any more in this thread though because closed mindedness pisses me off too much, especially those hopelessly stuck in the paradigms of the times, when in ten years much of what is believed to be proven now, will be disproven. It is a F#king joke.

Sorry for the rant, there is just nothing that pisses me off more than stupidity and lack of self actualized thought. I have an IQ on par with Stephen Hawking at 152 and to see people not able or more likely not willing to think for themselves at ALL is just frustrating.......

OOHOHHHHGGGGGGHHHHHH!!!!!!!!!!
I wouldn't be so quick to start an argument regarding physics or science in general with bagofpaper...

http://forums.azbilliards.com/showpost.php?p=1046796&postcount=91

jsp <~~ has a decent memory, with an IQ much less than Hawking

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#### CueAndMe

##### AzB Silver Member
Silver Member
After the post about the ball hitting the wall, I was able to picture a ball that was moving hitting a stationary cue tip and ther I am able to see how the CB would push the cue sideways. This also helps to picture how end mass would affect the amount of squirt. If there is more endmass then it would become more difficult for the CB to push the tip sideways and would have a greater affect on the diversion of the initial path.

I know you're pissed, but this is a good visual. I can see it more clearly now too. Thanks,
Jeff

#### Jal

##### AzB Silver Member
Silver Member
It is absolute folly to believe that all things that are observed in nature regarding waves are not true with radio waves. They MUST have a medium to travel through. They travel through the mdium of space/time. That is what I am saying. I'm sooo tired of people saying "we've done the experiments so THERE....." What experiments? It is possible that they were done incorrectly or misinterpreted.

That's like saying that the atomic clock experiments prove Einstein's theories of realtivity. BULL\$IT!!!!!. All the atomic clocks experiments prove is that an atomic clock up in the sky does not coincide with one that is close to the earth even though they started out the same. IT can be INFERRED that this MAY mean that time fluctuates close to a gravity source, but it is actually MORE likely that it infers that a gravity source affects the rate of fluctuation or frequency modulation of the atoms in whatever material is used for the atomic clocks.

This example is one of many where "PSeduo" modern science has claimed that an experiment proved something when it did NO SUCH THING. and the actual experimenters will usually admit, "to anyone that knows anything or chooses to think for themself" that it is not a proof but just evidence in support of something. IF you TRULY believe that anything cna be proven and not just supported, then it is YOU my friend, not I that is not a ture scientist.

I'm done with this thread.....

I was just about to admit that I may have been wrong about this idea, before this guy spouted off. After the post about the ball hitting the wall, I was able to picture a ball that was moving hitting a stationary cue tip and ther I am able to see how the CB would push the cue sideways. This also helps to picture how end mass would affect the amount of squirt. If there is more endmass then it would become more difficult for the CB to push the tip sideways and would have a greater affect on the diversion of the initial path.

I will not post any more in this thread though because closed mindedness pisses me off too much, especially those hopelessly stuck in the paradigms of the times, when in ten years much of what is believed to be proven now, will be disproven. It is a F#king joke.

Sorry for the rant, there is just nothing that pisses me off more than stupidity and lack of self actualized thought. I have an IQ on par with Stephen Hawking at 152 and to see people not able or more likely not willing to think for themselves at ALL is just frustrating.......

OOHOHHHHGGGGGGHHHHHH!!!!!!!!!!
Jaden, it's fun to come up with new theories in the hope that you've discovered something that science has missed. But I'd try to understand Newton's Laws and the conservation of momentum before taking on General Relativity. I suppose you have an alternate explanation for the precession of Mercury's orbit, for instance, but whatever it is, I for one wouldn't want to hear it unless I knew you at least understood the current working theory (or at least classical mechanics).

You are right about a certain amount of closed mindedness though. Most come here for social reasons I guess. They just don't have the time or patience for anything other than the usual B.S., or when willing to stretch a little, the pronouncements of certain high-profile posters on more technical matters. It is discouraging when you feel pretty certain that you understand something that's generally not understood, but it gets dismissed along with all the other mush.

Jim

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#### mikepage

##### AzB Silver Member
Silver Member
It is absolute folly to believe that all things that are observed in nature regarding waves are not true with radio waves. They MUST have a medium to travel through.

I really have no idea why you say this--other, perhaps, than that you desire it to be true.

[...]. I'm sooo tired of people saying "we've done the experiments so THERE....."

I'm sorry, but that is pretty much the whole point of science--that experiment is the sole arbiter of truth.

What experiments? It is possible that they were done incorrectly or misinterpreted.

Somebody already mentioned the Michaelson Morley expt. I think that's among the most elegant experiments in the history of science. Sure, it could have been done wrong (though it's so simple it's hard to imagine how) or misinterpreted (though the interpretation is so transparent it's hard to imagine how) or Michaelson & Morley could have been a couple pranksters making up the results or just plain lying.

But you have to remember those experiments were done when Einstein was an 8-year-old kid. And forget general relativity, which I don't understand. But special relativity, which do understand, would have to be thrown out the window if the MM results were a lie or a mistake. And there are thousands of experiments that confirm special relativity and ZERO that fly in the face of it.
[...]
This example is one of many where "PSeduo" modern science has claimed that an experiment proved something when it did NO SUCH THING. and the actual experimenters will usually admit, "to anyone that knows anything or chooses to think for themself" that it is not a proof but just evidence in support of something. IF you TRULY believe that anything cna be proven and not just supported, then it is YOU my friend, not I that is not a ture scientist.

What I think you're missing here is that "lack of ether" is not the theory or the hypothesis or whatever you want to call it. Rather EXISTENCE of a medium (ether) that would define the concept of being STILL is the hypothesis. If you take that hypothesis and deduce a NECESSARY CONSEQUENCE, like Michaelson & Morley did, and you DO THE EXPERIMENT and find the necessary consequence is not there, then the hypothesis MUST BE FALSE. And yes, that IS the way science works.

[...]
Sorry for the rant, there is just nothing that pisses me off more than stupidity and lack of self actualized thought. I have an IQ on par with Stephen Hawking at 152 and to see people not able or more likely not willing to think for themselves at ALL is just frustrating.......

OOHOHHHHGGGGGGHHHHHH!!!!!!!!!!

Hmmm Don't know mine, but I suspect I'd need at least the seven out and the breaks from you in an IQ test.

#### Corwyn_8

##### Energy Curmudgeon
Silver Member
If you take that hypothesis and deduce a NECESSARY CONSEQUENCE, like Michaelson & Morley did, and you DO THE EXPERIMENT.

So Michaelson and Morley looked for a difference in the speed of light due to traveling in perpendicular directions through an assumed moving ether. What happens when you apply special relativity to that expectation. It says that both speeds of light should be the same. Which is what the experiment showed. So since we should expect that result regardless of whether ether exists, are you still so sure?

Thank you kindly.

#### dr_dave

##### Instructional Author
Gold Member
Silver Member
Excellent post, Bob.

For those who want more information, everything Bob and others have mentioned so far in this thread (that is on topic) is described, illustrated, and demonstrated on the following resource pages:

what causes squirt?

endmass and stiffness effects

shaft squirt (CB deflection) testing

cue tip hardness effects

effects of light vs. tight grip

Concerning how the cue and CB speeds vary with tip offset from center, cue weight, and cue speed, that is covered in detail (with physics and math) in:

TP A.30 - The effects of cue tip offset, cue weight, and cue speed on cue ball speed and spin

Enjoy,
Dave

The stick transfers energy to the cue ball by compressing like a spring along its whole length. The compression wave happens at the speed of sound in the stick, which is about 13000 feet per second. This speed is the fastest that the butt can learn of something colliding with the tip. Some people make the mistake of thinking of the cue stick as being perfectly rigid and incompressible, but it's not. So, the shot proceeds like this: the stick is coming forward and the tip meets the ball. The tip starts to compress, force and acceleration of the cue ball start to build up. The ball also starts to compress, since it too is not incompressible. The ball has started to move, but is not up to the speed of the stick yet, and the stick has started to slow down as its energy is transferred to the cue ball. This continues until the tip (and ferrule and joint and butt) reach maximum compression along the length. At this exact point some amazing things are happening. The stick and ball are moving at the same speed. The force between stick and ball are at their maximum. The compression along the length of the stick (including the tip) is at its maximum. The energy stored in the spring-like compression of the tip (and stick and ball) are at their maximum. For a typical ball and stick, the speeds of the ball and stick are 75% of the original stick speed.

After this point of maximum compression, the ball is pushed forward from the tip by the compression of system. The ball starts to move even faster from this force and the stick continues to slow down. This "unwinding" process continues until the ball finally leaves the tip. At that point, the ball is going at about 130% of the original stick speed, and the stick has slowed down to about 50% of its original speed. (The 130% would be 150%, but the tip is not perfect in springing back to its original shape, and energy is lost.)

Now the hand comes in. Human flesh makes a much "softer" spring than the leather of a tip or the wood that is compressed along the length of the stick. Think of the tip as about the stiffest car spring you can imagine and your hand like a rubber band. The cue ball is gone by the time your hand -- which is still moving forward at full speed -- can wind up even a little. As the hand winds up on the stick and relaxes, which takes about 20 milliseconds, the hand is slowed to about 80% of its initial speed and the stick goes from 50% back up to 80% of its initial speed. Of course this re-acceleration of the stick by your hand is useless in that the cue ball is long gone.

How does a heavier stick affect things? It changes that 130% number. The formula is in Byrne's Advanced book, and somewhere in my columns in Billiards Digest and certainly in Ron Shepard's paper and Dr. Dave's book. A heavier stick through the spring action, puts slightly more energy into the cue ball.

As for how the weight of the stick affects the squirt, I think the answer is that it doesn't, much. Squirt is caused by the spinning cue ball pushing the stick to the side during the contact time of an off-center hit. The amount of squirt is determined by the mass that is being pushed to the side. Since the stick is very floppy side-to-side (as compared to length-wise compression), only the front part of the stick can participate in the squirt during the 1 millisecond or so of contact time. A heavier stick will increase the contact time a little, and that will increase the squirt a little, but I think this effect is pretty small.

Phrased technically, the transverse wave has a very slow propagation velocity along the length of the stick, and so the joint and butt cannot participate in the sideways push that causes squirt.

You should find Mike Page's discussion of his experiment with vise grips on the shaft which determined how much of the shaft participates in squirt.

As Fred mentioned, a major problem with some of the Jacksonville Project was that Iron Willie had too stiff a grip -- like vise grips -- and too hard a bridge. I have heard that Predator's current cue testing robot has fixed those problems to hold the cue more like a human at both ends.

As for some of your other questions, in theory the squirt should depend on stiffness of the cue since that should change the speed of the transverse wave. In practice, "end mass" seems to be a much better indicator of squirt than stiffness. There are stiff cues with little squirt and stiff cues with lots of squirt. A major red herring along the path of squirt studies was the fact that carom cues tend to be stiff but have relatively low squirt. They usually have smaller tips than pool cues.

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