spin transfered... a myth?

Slh said:
Many people don't believe spin can be transfered from the cueball to the OB.
This video proves it:
http://www.youtube.com/watch?v=4B4f...DvjVQa1PpcFM9Mm0drsH2FTDaYFWofVYi_sdnmBD1ZmM=

if the spin is transfered, we should see the vertical lines of the 10 ball change direction, right?
Mike Sigel doesn't believe in spin transferring. I just watched the dr. dave's video and it looks like the spin is transferring but why we can't see it on the 10 ball in the previous video? The spin transferred is so small we can't even see it?
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Spin transfer most definitely exists. Proof (mathematical, visual, and example-based) can be found in the videos and resources here:

Throw (both CIT and SIT) also most definitely exist. In fact, any time there is throw, there is also spin transfer (and vice versa). The two effects come hand in hand. For more info and supporting resources, see:

The amount of spin transfer and throw varies a lot with conditions, shot speed, amount of side spin, cut angle, and closeness to stun (no topspin or bottom-spin). For more info, see the list of throw effects here (see items 15-25 in the list under the videos):
and see:

For many useful examples of shots requiring and using throw and spin transfer effects, see:

Regards,
Dave
 
As much as this has been talked about and as many times as it has been stated I am shocked that people still remain oblivious.

The transfer of side spin depends on how clean and how worn the balls are. If the balls are dirty or they are worn so that the surface of the ball is not smooth then you increase the amount of friction between the balls on contact and that friction is what can cause the spin from the cueball to transfer to an object ball.

If you have perfectly clean new balls with totally smooth surfaces then the spin from the cueball will not transfer becaues there is no friction between the balls to transfer the spin.
 
Celtic said:
If you have perfectly clean new balls with totally smooth surfaces then the spin from the cueball will not transfer becaues there is no friction between the balls to transfer the spin.
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Correction: with smooth, clean balls, there is less friction (not none), and less spin will transfer.

There is also less spin transfer at faster speeds, with too much spin, and when there is any top or bottom spin. See the links in my previous post for more info and demonstrations.

Regards,
Dave
 
dr_dave said:
Correction: with smooth, clean balls, there is less friction (not none), and less spin will transfer.
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I am talking from a purely theoretical physics point of view. The same way physics looks at purely inelastic collisions between objects in complete vacumes where friction does not impeed studies of momentum and kinetic energy transfers.

There is not such thing as the "perfectly" clean pool ball or the "perfectly" smooth surface nor are the collisions 100% inelastic so yes, there is a small amount of spin even under ideal normal real world conditions because the balls are not perfectly clean and they are not perfectly smooth.

The theoretical perfectly inelastic collision between two objects that are 100% clean and completely smooth would have no friction and there would be NO spin transfer. That is simple reality and if you are going to argue against that you are arguing against 100's of years of core physics principles that reach back to Newtonian times.
 
finished ?

Perhaps Celtic's post was the perfect post to close this thread, or are you guys living in a vacuum ? And did the Thaiger actually make a concession to billard players having some insight over snooker players ?? Sarcasm ?

Thanks Bob and Dr. Dave and the physicist group.

Celtic said:
I am talking from a purely theoretical physics point of view. The same way physics looks at purely inelastic collisions between objects in complete vacumes where friction does not impeed studies of momentum and kinetic energy transfers.

There is not such thing as the "perfectly" clean pool ball or the "perfectly" smooth surface nor are the collisions 100% inelastic so yes, there is a small amount of spin even under ideal normal real world conditions because the balls are not perfectly clean and they are not perfectly smooth.

The theoretical perfectly inelastic collision between two objects that are 100% clean and completely smooth would have no friction and there would be NO spin transfer. That is simple reality and if you are going to argue against that you are arguing against 100's of years of core physics principles that reach back to Newtonian times.
Click to expand...
 
Celtic said:
I am talking from a purely theoretical physics point of view. The same way physics looks at purely inelastic collisions between objects in complete vacumes where friction does not impeed studies of momentum and kinetic energy transfers.

There is not such thing as the "perfectly" clean pool ball or the "perfectly" smooth surface nor are the collisions 100% inelastic so yes, there is a small amount of spin even under ideal normal real world conditions because the balls are not perfectly clean and they are not perfectly smooth.

The theoretical perfectly inelastic collision between two objects that are 100% clean and completely smooth would have no friction and there would be NO spin transfer. That is simple reality and if you are going to argue against that you are arguing against 100's of years of core physics principles that reach back to Newtonian times.
Click to expand...

In a purely Newtonian world, you are allowed to assume perfectly clean balls that collide without friction and %100 inelastically, hence no spin transfer.

The reality (or whatever you want to call it) is non-Newtonian.

There is no such thing as a perfect vacuum. At the smallest length scales imaginable, the fabric of the space-time has the intrinsic property called "quantum vacuum fluctuations". Hence, the collision between the balls, no matter how smooth and clean the balls are (%100 if you want), can never be %100 inelastic, which is the correct theoretical point of view in the light of quantum mechanics.

-> SPIN IS ALWAYS TRANSFERRED :thumbup:
 
Celtic said:
As much as this has been talked about and as many times as it has been stated I am shocked that people still remain oblivious.

The transfer of side spin depends on how clean and how worn the balls are. If the balls are dirty or they are worn so that the surface of the ball is not smooth then you increase the amount of friction between the balls on contact and that friction is what can cause the spin from the cueball to transfer to an object ball.

If you have perfectly clean new balls with totally smooth surfaces then the spin from the cueball will not transfer because there is no friction between the balls to transfer the spin.
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I am not a stupid man by any means and do not ignore common sense. Although what you say makes perfect sense at first, this has not been my observation. I find more spin transfers directly after removing my balls from the cleaner than later on when they're dirty. I believe that this is caused by the decrease in friction where the ball rests on the cloth when clean is greater than the decrease in transfer from the balls colliding and thus the net effect of english transfer is actually greater with clean balls. Ever notice how long a ball spins like a top when clean compared to dirty? If you don't believe me do your own experiments. The difference is noticeable between clean and dirty balls and it's not in the direction one might think. That's my story and I'm sticking to it.

Edit: the same phenomenon occurs with spin induced throw, clean vs dirty balls.
 
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DoubleD said:
First off, the effect of the friction between a ball spinning on the table about the vertical axis and the cloth is very low.

Second, I wonder if you are (as seems to be common) waxing your balls?

Third, there is a neat trick to prove that dirty, chalk covered balls have a higher coefficient of friction than very clean balls. Grab four balls and stack them in a pyramid in the center of the table. Clean balls should not stand. Now rub chalk on one of the balls where it is going to make contact with the others and try again.

dld

dld
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First, I don't wax my balls. (Shave yes, wax no). I use Aramith ball cleaner. Second I think you missed the point. The point is that what I describe where clean balls transfer more spin effect than dirty ones is real. I have seen it enough that this isn't even up for debate in my mind. I know what I see. I am not sure about why though because it does seem to defy logic as illustrated by your chalk trick. The theory I put forward is all I can personally think of why this happens that makes any sense. I think the ball sitting on the cloth generates a lot of friction when the ball is dirty compared to when It's clean. I also think this friction is more than the same dirty contact point between the balls can compensate for. Thus even though if the balls were on glass, the dirty ones would tranfer more spin, this isn't what happens on a pool table. When ever you get unexpected results with an experiment there's always a reason for it. Clean half your balls and leave the other half dirty and hit some before you think I'm nuts.
 
theory and practice

DoubleD said:
Therein is the problem with physics--and believe me, I have had this argument with a former friend who was a physics major while I studied engineering.

If you neglect friction in this case, you might as well neglect gravity, which means that not only will the balls not drop in the pockets, we would be playing three dimensional pool and it would last for precisely one shot because the balls would never stop moving.

The fact of the matter is that even if the balls were completely clean, there would still be friction. Friction is a property of the materials, not of dirt or surface finish. True, dirt and surface finish affect the friction, but they are not only factor.

Physicists neglect factors because they want to isolate other factors. People living in the real world use what the physicists learn to create models of what happens in the real world.

My buddy used to claim that physicists were more important to society because they explore everything to the nth degree while engineers estimate or round things. I finally got him to concede that if engineers designed or built the way physicists analyze we would have nothing because no invention would ever be perfect. Ogg would have died carving that first stone wheel because he would figure out that the axle wasn't perfectly centered and the wheel wasn't completely round. He would have invented new measuring techniques, but would have figured out that they were not perfect. Ogg's legacy would have been an unfinished wheel and the most accurate measuring methods the world had ever seen--and nobody would use them because they still weren't perfect.

So, yeah, physics and physicists are great, but we cannot allow ourselves to apply their methods to real life.

dld
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While we sometimes got on the same page and great things happened I spent a lot of time trying to convince the theory guys that theory didn't work in the real world when I was in R&D. We often spent thousands of dollars to prove something didn't work. The theory guys always just said, "aw well, it shoud have worked" and forgot about it. Never mind that they had insisted on trying something that had been tried a thousand times before and failed every time.

It was still one of the most fun jobs I ever had and I was left scratching my head over some things that did work like heavier than air craft flying using electricity and no moving parts.

Hu
 
There is a lot of spin transfer, the easiest way to observe it is when you hit a bank shot. It works the same as the gears inside a clock, even thought the surface of the pool balls seems very smooth there are a lot of imperfections.Friction happening between the two balls is enough for the spin to transfer.
 
As with other topics, this one has come up a number of times on here. A year or two ago, I did an experiment to prove or disprove the existence of transferred spin. What some fail to take into account, is that anytime you hit an ob at an angle, you will introduce spin to the ob and the cb. Essentially, the part of the cb that contacts the ob will immediately want to stop, but the part that doesn't contact the ob wants to keep going forward. Because of that, the cb rotates or spins. An easy test of this is to have a ball near the side pocket straight in to the side. Put the cb at an angle to it and cut it in with no spin on the cb. When the cb hits the end rail, it will not come straight back on the line it went in on, it will have spin on it and come off the rail at an angle.

So, the only real way to tell if spin is transferred is on a straight in shot. Due to deflection or squirt of the cb, you have to have a way to make sure you hit the ob square. I made up a jig of two parallel boards just a hair wider than the cb so the cb could travel through them without a ton of friction. I then placed an ob in a direct line to the cb. Shot with no spin, the ob comes straight back to where it was after hitting a rail. Shot with max spin on the cb, the ob will pick up some spin and not come straight back. The amount of spin transferred from one foot between the cb/ob and 4' to the rail and 4' back was only about two inches. Not a lot, but it proves that spin is transferred.
 
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DoubleD said:
... So, yeah, physics and physicists are great, but we cannot allow ourselves to apply their methods to real life.

dld
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It depends on the physicist. No competent physicist would ignore friction in billiards. A competent physicist understands that friction exists and could predict, even in the absence of data about pool balls, what the effects would be and how they are related to the coefficient of friction between the balls.

One of the most important parts of physics is figuring out which "second order" effects might enter the problem and then how they might affect the outcome. Entire industries have been founded on those minor or second-order effects.

I'd consider Coriolis a physicist (rather than an engineer) and he spent a lot of time thinking about friction at billiards.

Mathematician are a different breed, of course. Here is the start of an article from a math journal I get.
IMG_0009.JPG
 
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