Side spin does not transfer

[Cornerman]

In the case of left and right spin, the OB gets twisted in a forward motion to cause the OB to have an effect of top right or top left. But never a transfer.;

You're arguing phantoms. It sounds like a simple semantic issue. Twisted = spin.

When you say

"the OB twisted in a forward motion to cause the OB to have an effect of top right or top left,"


that's the same as saying,

"the spin of the cueball induced a little twist on the object ball upon contact,"



which is the same in layman's terms as saying,

"the cueball transfers a little spin to the object ball."

Fred

 

[Chris]

Pete Lafond said:

Needless to say, even though I believed this, I felt it deserved a test. The results were accurate. Right English did not transfer left English, nor the reverse. The OB did twist. So as I stated the only way the CB can cause an OB to spin left or right is through contact on an angle. Many times when players hit left or right English, the CB curves enough to create an angle which is contact induced.

Out of curiosity, did you do this test with balls that had just been cleaned? If so, the coefficient of friction would be substantially lower, making the effects of the transferred side spin much more subtle.

 

[CaptainJR]

I'm going to try to stay away from this by asking a question. This will help me know if I'm thinking about what everyone is talking about here. We all know that when you cut a shot without using any english the force of the cue ball will throw the object ball a little in the direction of an undercut. More so on slow shots than shots with speed.

If this is so that means that the friction of the cue ball, object ball collision is causing this. If this friction causes this throw, why wouldn't it transfer some spin.

This also fits in with putting a little natural english on a slow shot to prevent skid.

Still thinking?

 

[Travis Bickle]

Another way you can know that there is some transfer of english is to hit a cut shot down the rail with inside english. Everybody knows these shots tend to fall easier with inside than with other kinds of spin. Though it's hard to see the action on the ob, watch how shots that would otherwise jaw will often spin themselves in, if not hit too hard with inside.

 

[Cornerman]

No confusion here. I am discussing the effects that take place are not to be misleading to those that think side spin causes side spin. In fact a twist occurs resulting in a diagonal one. The accuracy of this is important to the outcome expected.

The sidespin causes the side spin. Nothing else causes the sidespin in a direct linear collision by a spinning cueball hitting a stationary object ball.

The instantaneous velocity of the cueball contact point is tangential to the contact point of the object ball. Friction dictates that there is a force vector perpendicular to the contact line. The friction vector times the radius of the ball is the torque that the object ball sees. The torque is the spin.

If you ignore the resultant linear motion of the object ball (which you I believe are calling a diagonal motion), and only focus on the object ball center point, you will clearly see a resultant horizontal rotational velocity, however small it may be. The rotational velocity (in relation to the object ball center) parallel to the horizontal plane is the amount of transferred spin.

I think the following video clearly shows the transfer, before the table cloth induces forward roll. You can clearly see the vertical line rotate about the center of the object ball by a few degrees before the table takes over. The rotational velocity is very small, but it exists and can be profound. Just because the table takes over with the forward roll, that object ball still has a rotational velocity component in a plane parallel to the bed.

http://www.engr.colostate.edu/~dga/pool/high_speed_videos/HSV4-6.htm

There is nothing else in this collision that creates that motion. You'll notice the cueball actually hits the left side of the object ball. A normal shot would then cause left-hand spin (clockwise from the top). But in this shot, the cueball has left-hand english, and the object ball clearly turns counter clockwise by a few degrees.

Fred

 

[CaptainJR]

I'm going to try to stay away from this by asking a question. This will help me know if I'm thinking about what everyone is talking about here. We all know that when you cut a shot without using any english the force of the cue ball will throw the object ball a little in the direction of an undercut. More so on slow shots than shots with speed.

If this is so that means that the friction of the cue ball, object ball collision is causing this. If this friction causes this throw, why wouldn't it transfer some spin.

This also fits in with putting a little natural english on a slow shot to prevent skid.

Still thinking?

Shesh JR, Read everything before saying anything.

twist = spin

 

[Colin Colenso]

Twist = a component of side spin.

It's no different in nature to the sidespin induced by a cut shot.

A common bank shot it to cut a ball say 5 degrees right of straight with left english. Instead of the OB having left english, the spin induced is right english, and as a result the OB banks wider to the right.

This can be done with the CB just an inch from the OB. Swerve is irrelevant. The shot will work with bottom, center or top applied to the CB, but to slightly varying degrees.

If a center hit, the OB leave the CB with pure slide and about 2-3% of the sidespin that the CB had, but in the opposite direction. Later the linear motion of the OB is converted to natural roll. This does not mean the side spin is not on the ball, it just looks different. The component of side spin will gradually reduce due to friction. Just as it does if I play the CB along a table with a touch of side.

I'm not sure I'm understanding Pete's exact claim here. Especially the term twist.

Added: I just saw Cornerman's post above, the video he links to show the shot I am talking about:
Here it is again: http://www.engr.colostate.edu/~dga/p...eos/HSV4-6.htm

 

[Colin Colenso]

The instantaneous velocity of the cueball contact point is tangential to the contact point of the object ball. Friction dictates that there is a force vector perpendicular to the contact line.
Fred

That's not exactly true. There can be 3 or more degrees spin induced throw (SIT), though that does not make any difference to the observed fact that some spin is transfered.

It just adds an extra thing to compensate for, and an extra layer of confusion for the experimenter. Some, noticing this SIT, may assume it is wholly responsible for the wider or shorter angles (depending on which side is used) created on straight shot banks.

But if they allow for the SIT by aiming slightly off straight in the other direction, they will send the OB to the same cushion point on the straight line, and thereafter notice the transfered spin take effect.

 

[Gregg]

If spin cannot be transferred to an object ball, then how do you explain these high speed videos.

http://www.engr.colostate.edu/~dga/pool/high_speed_videos/new/HSVA-84.htm

Trick photography. LOL

I am just starting to open the door to good position play and ball pocketing skills, but man, if you don't understand the concept of "throw", your really going to limit yourself. People who don't understand the basic concept shouldn't be using any side spin/English yet, and should keep shots limited to vertical axis (high/low, center) hits.

 

[Cornerman]

The instantaneous velocity of the cueball contact point is tangential to the contact point of the object ball. Friction dictates that there is a force vector perpendicular to the contact line.
Fred

That's not exactly true. There can be 3 or more degrees spin induced throw (SIT), though that does not make any difference to the observed fact that some spin is transfered.

I'm not sure what you're saying isn't true, Colin. At contact, there are two contact points. One on the object ball and one on the cueball. The instantaneous velocity of the cueball's contact point has to be perpendicular to the contact line (the line formed between the centers of the balls through the two contact points), since the instantaneous velocity of that point by definition is perpendicular to it's respective radius line.

Or was there something else that was supposed to be quoted?

Fred

 

[pbat2751]

Where is Randy G when you need him?

 

[Colin Colenso]

I'm not sure what you're saying isn't true, Colin. At contact, there are two contact points. One on the object ball and one on the cueball. The instantaneous velocity of the cueball's contact point has to be perpendicular to the contact line (the line formed between the centers of the balls through the two contact points), since the instantaneous velocity of that point by definition is perpendicular to it's respective radius line.

Or was there something else that was supposed to be quoted?

Fred

I don't see that that makes sense for a spinning ball Fred, unless I am not visualizing what you are saying.

First I thought you were talking about the OB travelling perpendicular.

But now seems you're talking about the velocity of the CB contact point. If a CB is spinning on contact, the velocity of that point on the CB that makes contact can be in quite a lot different direction to the line between the center of the 2 balls. For a slow rolling finger spin CB, the difference could be nearly 90 degrees.

Am I on a different page?

 

[Chris]

If a CB is spinning on contact, the velocity of that point on the CB that makes contact can be in quite a lot different direction to the line between the center of the 2 balls. For a slow rolling finger spin CB, the difference could be nearly 90 degrees.

The direction of the force from the rotation of the cue ball as it impacts the object ball will always be on a plane that is perpendicular to the line between the center of each ball. The angle of cut does not matter, nor does the direction of spin.

It is a property of tangents. All tangents are perpendicular to the radial sharing a point with the tangent. The force due to a rotating cue ball will always have a direction tangential to the object ball. If two spheres share a tangent, that tangent will always be in line with the centers of the two spheres.

 

[pete lafond]

Twist = a component of side spin.

It's the effect.

What I am saying is different what everyone else had been saying before. Point. My earlier statement was that (in far a away prevous post) there is no way the the CB imparts side english on the OB when hit with side english. In other words the OB does not travel forward spinning sideways. It does not happen. What happens is that the spinning CB and OB against the felt cause a twist which results in top left or right english.

It's no different in nature to the sidespin induced by a cut shot.

What you are taking about here is something that can get into it's own thread. eg You can negate the OB from acquiring spin on a cut shot with side english use.

It is different because side spin can be minimized
A common bank shot it to cut a ball say 5 degrees right of straight with left english. Instead of the OB having left english, the spin induced is right english, and as a result the OB banks wider to the right.

Forget the CB for a moment. Hit the OB, no CB, with your cue with right English only straight ahead into the rail. Next, the same shot hit with the same speed but instead us running English. In each case the angle of the rail was different. If side English were truly transferred then just as the first test, the OB would run longer. This is my point and had been my point. A twist occurs and the OB has either Top left or top right English, not left or right English.

This can be done with the CB just an inch from the OB. Swerve is irrelevant. The shot will work with bottom, center or top applied to the CB, but to slightly varying degrees.

No need for swerve in this case except to compensate our aim for it. (the only way to minimize it is to hit a low English on the CB). We do not want to use low here only left or right.

If a center hit, the OB leave the CB with pure slide and about 2-3% of the sidespin that the CB had, but in the opposite direction. Later the linear motion of the OB is converted to natural roll. This does not mean the side spin is not on the ball, it just looks different. The component of side spin will gradually reduce due to friction. Just as it does if I play the CB along a table with a touch of side.

Natural roll takes a while. eg The top right will eventually become top only.

 

[pete lafond]

The direction of the force from the rotation of the cue ball as it impacts the object ball will always be on a plane that is perpendicular to the line between the center of each ball. The angle of cut does not matter, nor does the direction of spin.

It is a property of tangents. All tangents are perpendicular to the radial sharing a point with the tangent. The force due to a rotating cue ball will always have a direction tangential to the object ball. If two spheres share a tangent, that tangent will always be in line with the centers of the two spheres.

Add in the felt result in a twist.

This is why I always tell players who ask how to aim to always lock in on the OB before pulling the trigger. This gives the player a chance to really see the entire shot. Unless they are brand new players I tell them to forget the ghost ball if they should bring it up. It's not real and does not place the focus on the OB. Seeing the OB gives immediate feedback not only on how shots resulted but also the spin and what took place enabling a higher level of finesse in their play. Also it enables players to quickly adjust to conditions of play because this to requires sound observation.

I understand aiming is out-of-topic, but in my opinion this method of aiming does give the player a complete sense of what is going on - side spin transfer.

 

[Jaden]

You're worng Pete...

Add in the felt result in a twist.

This is why I always tell players who ask how to aim to always lock in on the OB before pulling the trigger. This gives the player a chance to really see the entire shot. Unless they are brand new players I tell them to forget the ghost ball if they should bring it up. It's not real and does not place the focus on the OB. Seeing the OB gives immediate feedback not only on how shots resulted but also the spin and what took place enabling a higher level of finesse in their play. Also it enables players to quickly adjust to conditions of play because this to requires sound observation.

I understand aiming is out-of-topic, but in my opinion this method of aiming does give the player a complete sense of what is going on - side spin transfer.

The forward motion of the OB is what gives it that slight forward spin, the side spin is caused by the spinning of the CB as contact is made compression occurs and during this compression from the force of contact some of the spin is transferred to the OB from the CB/

 

[Colin Colenso]

It's the effect.

What I am saying is different what everyone else had been saying before. Point. My earlier statement was that (in far a away prevous post) there is no way the the CB imparts side english on the OB when hit with side english. In other words the OB does not travel forward spinning sideways. It does not happen. What happens is that the spinning CB and OB against the felt cause a twist which results in top left or right english.

I believe the effect would be the same if we had zero friction cloth. I don't see any need to introduce the cloth into this.

Forget the CB for a moment. Hit the OB, no CB, with your cue with right English only straight ahead into the rail. Next, the same shot hit with the same speed but instead us running English. In each case the angle of the rail was different. If side English were truly transferred then just as the first test, the OB would run longer. This is my point and had been my point. A twist occurs and the OB has either Top left or top right English, not left or right English.

If the CB is sliding, the OB will leave with just a touch of sliding english. Anyway, there is no difference between a ball that starts with pure side and begins to roll under friction and one that is hit with a component of top and side english.

In rotational phyics, we divide the ball into 3 axis and calculate the rotational properties about each of these. This works and makes sense if you study it. But twist is just an unclear term. I don't think you have identified any physical characteristic that is different to what is described by components of various spin about the different axis. A top left shot is actually rotating about 2 axis and possibly 3 if it was struck with a non-parrallel hit.

Natural roll takes a while. eg The top right will eventually become top only.

That's true, and a finger flick ball can lose its roll component but continue spinning stationary.

Sometimes thinking in terms of rotational axis seems counter intuitive, but I think it is the only way to understand what is going on.

 

[pete lafond]

The forward motion of the OB is what gives it that slight forward spin, the side spin is caused by the spinning of the CB as contact is made compression occurs and during this compression from the force of contact some of the spin is transferred to the OB from the CB/

Yes, that is what I stated in my first post. Simply put, the force of the ball moving forward - spin plus felt friction results in a twist. The forward motion is the primary energy. More importantly, this thread is about what the player should expect when applying side spin because understanding and manipulating this is the enabler to making critical shots.

 

[pete lafond]

I believe the effect would be the same if we had zero friction cloth. I don't see any need to introduce the cloth into this.


If the CB is sliding, the OB will leave with just a touch of sliding english. Anyway, there is no difference between a ball that starts with pure side and begins to roll under friction and one that is hit with a component of top and side english.

In rotational phyics, we divide the ball into 3 axis and calculate the rotational properties about each of these. This works and makes sense if you study it. But twist is just an unclear term. I don't think you have identified any physical characteristic that is different to what is described by components of various spin about the different axis. A top left shot is actually rotating about 2 axis and possibly 3 if it was struck with a non-parrallel hit.



That's true, and a finger flick ball can lose its roll component but continue spinning stationary.

Sometimes thinking in terms of rotational axis seems counter intuitive, but I think it is the only way to understand what is going on.

Felt friction is a major contributor, without it the outcome would be different.

Anyway, I am describing what happens in the real world for pool player. What to take notice of that can change the shot. eg. Side spin and running english are not the same. The earlier thread stated side spin which is what I tried to go back and to clear up.

 

[Chris]

Add in the felt result in a twist.

The roll of the cue ball, or lack thereof, must be taken into consideration. It is possible that this roll be effectively zero at the time the cue ball impacts with the object ball. In such cases, if the instantaneous velocity of the side spin of the cue ball at point of impact and the co-linear component of the velocity of the cue ball relative to the bed of the table are not equal to zero, the resulting movement of the object ball will include pure side spin.