Throw - Snooker balls vs. Pool balls

[jsp]

I've never played snooker before. But from watching videos of snooker online, I have this strong sense that snooker players don't need to compensate for the effects of throw (whether contact-induced or spin-induced) nearly as much as pool players. For those who have played both snooker and pool, is there any truth to my feeling?

For example, given a half ball hit using stun (no side spin or forward roll at impact) and the same CB speed, would the throw angle be greater for pool balls compared to snooker balls? (And given the same degree of ball polish - if that can somehow be measured and equalized.) My gut feeling is the throw angle for pool balls is considerably larger than snooker balls for this shot experiment.

Another more theoretical question. Given the same exact ball material (I don't know if pool and snooker balls are made from the same exact material), would the ball with a smaller diameter fundamentally have less throw compared to the larger ball? I haven't thought this through in great detail, but my initial thought is that that ball with a smaller diameter would fundamentally have less throw.

 

[PoppaSaun]

I've never played snooker before. But from watching videos of snooker online, I have this strong sense that snooker players don't need to compensate for the effects of throw (whether contact-induced or spin-induced) nearly as much as pool players. For those who have played both snooker and pool, is there any truth to my feeling?

For example, given a half ball hit using stun (no side spin or forward roll at impact) and the same CB speed, would the throw angle be greater for pool balls compared to snooker balls? (And given the same degree of ball polish - if that can somehow be measured and equalized.) My gut feeling is the throw angle for pool balls is considerably larger than snooker balls for this shot experiment.

Another more theoretical question. Given the same exact ball material (I don't know if pool and snooker balls are made from the same exact material), would the ball with a smaller diameter fundamentally have less throw compared to the larger ball? I haven't thought this through in great detail, but my initial thought is that that ball with a smaller diameter would fundamentally have less throw.

The cut- and spin-induced throw will be the same for pool and snooker balls.

 

[BasementDweller]

Well I guess that's settled.

 

[PoppaSaun]

Well I guess that's settled.

Sure is. Common sense combined with the slightest knowledge of physics makes it easy.

In case anyone is confused, I'll explain it: The size of the balls doesn't matter, because in either case it is assumed that the two balls in the collision are the same size. Thus, the equation has ball size on both sides, and it drops out.

The material is the same, so the friction component is the same.

The only factor which might make a bit of difference is the difference in the nap of the snooker cloth.

 

[skip100]

On snooker broadcasts they have a lot of great down the line camera views where you can see that the balls indeed appear to throw just like pool balls.

With the tight pockets players also appear to stay much closer to center axis though.

 

[jsp]

In case anyone is confused, I'll explain it: The size of the balls doesn't matter, because in either case it is assumed that the two balls in the collision are the same size. Thus, the equation has ball size on both sides, and it drops out.

But in my example I stated the CB velocities for both cases remain the same. So everything doesn't exactly scale as you think it would. Otherwise, the velocity of the pool ball CB will be faster than snooker ball CB.

The material is the same, so the friction component is the same.

First of all, are the materials exactly the same?

And even if the materials are exactly the same, I don't think the friction component remains exactly the same if the balls were traveling the same velocity, as I stated above.

 

[Cornerman]

Regardless of the exact amounts, the snooker world knows about throw and kick.

Watching the recent Crucible, I took still snapshots of Mark Selby clearly using side spin on cut shots, even if the cueball wasn't going to any cushion.

And the recent discussion on the Barry Stark coaching videos, one of his videos (the next one that popped up), he goes through side spin and how it throws the ball.

I think it's fair to say that the amount of throw should be about the same.


Freddie

 

[jsp]

Regardless of the exact amounts, the snooker world knows about throw and kick.

I know. But that wasn't the question.

I think it's fair to say that the amount of throw should be about the same.

For the same CB speed and ball conditions? I'm not convinced that the amount of throw is the same. But then again, I've never played snooker before...so you may be right. But it just doesn't feel right to me.

 

[PoppaSaun]

I know. But that wasn't the question.


For the same CB speed and ball conditions? I'm not convinced that the amount of throw is the same. But then again, I've never played snooker before...so you may be right. But it just doesn't feel right to me.

All of the factors cancel out, except for angular velocity. It is likely that the spin-induced throw would be different for equal cueball velocities and angular velocities.

The cut-induced throw will be nearly identical.

 

[Cornerman]

I know. But that wasn't the question.

But when you stated this:

I've never played snooker before. But from watching videos of snooker online, I have this strong sense that snooker players don't need to compensate for the effects of throw (whether contact-induced or spin-induced) nearly as much as pool players. For those who have played both snooker and pool, is there any truth to my feeling?

Maybe my response helps to reframe your thoughts in order to absorb the responses. If you already feel they don't compensate nearly as much (which I'm saying may be a false feeling), then any answer will have to go through your pre-filter. I'm just rebutting your statement based on latest information and reality. I hope that makes sense.

 

[Cameron Smith]

With the tight pockets players also appear to stay much closer to center axis though.

I never go further than about a tip off centre. That is always enough to get me where I need to go. A half tip can often do the job too.

I can't comment to a scientific certainty, but I compensate about the same between both games. I aim thicker on inside english shots and barely have to compensate for outside.

 

[Bob Jewett]

I think it is possible that there is some small change in the amount of throw with the smaller balls. The variation of friction with a change in pressure between the surfaces will be a little different for the "sharper" curve of the smaller ball.

However, I would not expect the change to be any larger than the % difference in the diameters of the balls. That is 2.25 vs. 2.0625. That is less than 10%. You see far larger differences in throw due to how the surfaces of the balls have been treated. Dr. Dave did a study of how surface preparation affects throw.

Here is a bank shot that is relatively easy to do on a snooker table (with a few tries:wink: Put the pink ball on the baulk line exactly three ball spaces from the long cushion. At the other end of the table, on that same long cushion, place three red balls frozen in a line sticking out from the cushion. Without throw it is barely possible to bank the pink off the far end cushion, barely miss the reds by an atom, and return to its starting space. With throw it is possible to twist the pink off the far cushion into the baulk pocket it is closest to.

Here is the shot diagram from Virtual Pool 4, which does model the friction but it is not quite as high as I have seen with reasonably new, polished, snooker balls. (I had to place the pink slightly more than 3 balls from the cushion to get the shot to work for the VP conditions.)



It would be simple enough to do a test with a three-ball combination as shown with the three balls in the D. See if the ball on the brown spot is sent off-line as much as the same combo with pool balls.

 

[MitchAlsup]

Common sense combined with the slightest knowledge of physics

That leaves out most pool players.

 

[jsp]

All of the factors cancel out, except for angular velocity. It is likely that the spin-induced throw would be different for equal cueball velocities and angular velocities.

The cut-induced throw will be nearly identical.

If things were to scale completely, then a ball with 2x the diameter would have to be hit with 2x the velocity in order to keep the velocity measured in units of diameters per time constant for both cases.

But in my example, both balls are hit with the same absolute velocity. So the larger ball has a slower velocity in terms of diameters per time compared to the smaller ball. If the coefficient of friction has a diameter component to it, then the differences in velocity (again, measured in diameters per time) could make a non-negligible difference in throw.

But this all assumes the same material for both balls. Again I ask the question... Are snooker and pool balls made out of the exact same material? After 5 minutes of Googling, this is what I got for the diameters and masses of each ball....

Snooker Ball => 5.25oz, 52.5mm
Pool Ball => 5.75oz, 57.2mm

Given these measurements, the density of the snooker ball calculates to be 18% greater than the density of the pool ball [(5.25/52.5^3)/(5.75/57.2^3)]. All other things being equal, I can see how the the higher density ball would throw less than the lower density ball.

 

[BasementDweller]

Hey -- I said this was settled.

 

[jsp]

I think it is possible that there is some small change in the amount of throw with the smaller balls. The variation of friction with a change in pressure between the surfaces will be a little different for the "sharper" curve of the smaller ball.

That is my intuition as well.

However, I would not expect the change to be any larger than the % difference in the diameters of the balls. That is 2.25 vs. 2.0625. That is less than 10%.

It's still a difference. But that assumes the densities of the balls are the same. What do you think of the density numbers in my previous post? If the snooker ball is more dense then the pool ball, then that would also lead to less throw for snooker balls.

It would be simple enough to do a test with a three-ball combination as shown with the three balls in the D. See if the ball on the brown spot is sent off-line as much as the same combo with pool balls.

I'd love to do such an experiment if I had the resources.

 

[Bob Jewett]

... But this all assumes the same material for both balls. Again I ask the question... Are snooker and pool balls made out of the exact same material? After 5 minutes of Googling, this is what I got for the diameters and masses of each ball....

Snooker Ball => 5.25oz, 52.5mm
Pool Ball => 5.75oz, 57.2mm

Given these measurements, the density of the snooker ball calculates to be 18% greater than the density of the pool ball [(5.25/52.5^3)/(5.75/57.2^3)]. All other things being equal, I can see how the the higher density ball would throw less than the lower density ball.

Well, it might be more accurate to measure some balls. The balls from a brand new set of Aramith tournament snooker balls weigh 142 grams. They are the standard 2 1/16-inch size or 5.24cm. A ball from a Super Pro pool set weighs 166 grams. Those calculate out to densities of
Pool ball 1.699 grams/cc
Snooker 1.885 grams/cc

That's about a 10% difference. I'm surprised that they are that different.

The simple physics says that the density should have no effect on the throw. The throw is determined by the coefficient of friction between the balls and the rotation and direction of motion of the balls (for spin-induced and collision-induced parts). A more complete model takes into account that the friction varies some (but not directly) with speed/pressure/velocity. Even so, the 10% difference in density should have minimal effect on the throw.

 

[dr_dave]

For the same CB speed and ball conditions ... I'm not convinced that the amount of throw is the same.

This is very easy to test for somebody who has access to both pool and snooker equipment. Unfortunately, I do not; otherwise, I would have done the test before writing this message. Just hit two frozen balls with the same cut angle and same speed (based on ball travel distance) on both tables and measure how far the 2nd ball throws over the same distance. The following video demonstrates how to do it:

NV D.16 - Pool ball cut-induced throw and cling/skid/kick experiment

If the surface properties are similar (regardless of the size and density), I would expect the amount of throw should be no different. If you look at any of my analyses involving throw (e.g., TP A.14), ball mass and radius do not affect the results, because as long as the CB and OB are homogeneous spheres of the same mass, throw is independent of ball size and weight.

Regards,
Dave

 

[dr_dave]

I think it is possible that there is some small change in the amount of throw with the smaller balls. The variation of friction with a change in pressure between the surfaces will be a little different for the "sharper" curve of the smaller ball.

So you think the smaller radius of curvature might result in less throw?

Another factor (I think) is the compression of the air between the balls during ball approach and impact. With small balls, the air might be able to get out of the way slightly more easily (especially on faster-speed shots, where throw is often less, I think in part because of the air-compression effect), allowing the surfaces to interact more fully and create more friction. If this is the case, smaller balls might exhibit slightly more throw at some speeds???

However, I would not expect the change to be any larger than the % difference in the diameters of the balls. That is 2.25 vs. 2.0625. That is less than 10%. You see far larger differences in throw due to how the surfaces of the balls have been treated. Dr. Dave did a study of how surface preparation affects throw.

For those interested, results of that study are available here:

ball surface treatment throw and cling effects

Regards,
Dave

 

[Bob Jewett]

As for the effect of an air cushion, if that does exist I would expect it to be less important for denser balls or for thinner air. Does anyone here have a sufficiently large vacuum chamber?