Cue Ball Curve

Tennesseejoe

Tennesseejoe

AzB Silver Member
Silver Member
If you hit the cue ball on the vertical center, with side English, and with a perfectly level cue...there should be NO cue ball curve. In the same situation but with an elevated cue, will there be more CURVE with high English or low English?

Note: a perfectly level cue is possible with a very large table and is used here only as an example for a reference point.
 
G

Gorramjayne

AzB Silver Member
Silver Member
Are you talking about using pivot English? It's hard to follow.


Speaking generally about all types of english, it actually depends on how much elevation you're talking about and where you're hitting. Hitting top with sidespin and an elevated cue will make the CB swerve more initially because the CB is being pushed into the cloth to start with, digging in and propelling itself in the direction of its spin. Hitting with low sidespin regardless of cue elevation, you're generally hitting a bit harder to get the CB there before draw wears off, but the CB will swerve, curving after it's traveled a bit. You use an purposely elevated cue less when hitting low on the ball, but if you do use an elevated cue and hit near the miscue limit, you'll get a semi-masse where the CB curve comes in late.

Short of it is, a CB will curve more at the start with a top CB hit, and the curve will be a little delayed with bottom, but I don't know that one actually curves less, speed being equal. It's just you typically hit bottom with a bit more force so the CB gets where it's going before you see the full curve of the ball show up, but the CB will curve.



And it's absolutely untrue that a level cue will result in no CB curve.. A level cue will delay the transfer of sidespin to the cloth and the onset of the curve, especially with firmer hits but its an inescapable conclusion of physics that the ball will curve unless its rotation is the same as its direction of travel. Even if you had magic frictionless cloth, the spinning ball would still curve just because of how a spinning body alters airflow over its surface. See: Magnus effect.
 
Tennesseejoe

Tennesseejoe

AzB Silver Member
Silver Member
Thanks. This is the answer I was looking for. You have made a welcome addition to the forum.


Gorramjayne said:
Are you talking about using pivot English? It's hard to follow.


Speaking generally about all types of english, it actually depends on how much elevation you're talking about and where you're hitting. Hitting top with sidespin and an elevated cue will make the CB swerve more initially because the CB is being pushed into the cloth to start with, digging in and propelling itself in the direction of its spin. Hitting with low sidespin regardless of cue elevation, you're generally hitting a bit harder to get the CB there before draw wears off, but the CB will swerve, curving after it's traveled a bit. You use an purposely elevated cue less when hitting low on the ball, but if you do use an elevated cue and hit near the miscue limit, you'll get a semi-masse where the CB curve comes in late.

Short of it is, a CB will curve more at the start with a top CB hit, and the curve will be a little delayed with bottom, but I don't know that one actually curves less, speed being equal. It's just you typically hit bottom with a bit more force so the CB gets where it's going before you see the full curve of the ball show up, but the CB will curve.



And it's absolutely untrue that a level cue will result in no CB curve.. A level cue will delay the transfer of sidespin to the cloth and the onset of the curve, especially with firmer hits but its an inescapable conclusion of physics that the ball will curve unless its rotation is the same as its direction of travel. Even if you had magic frictionless cloth, the spinning ball would still curve just because of how a spinning body alters airflow over its surface. See: Magnus effect.
Click to expand...
 
Straightpool_99

Straightpool_99

I see dead balls
Silver Member
Tennesseejoe said:
If you hit the cue ball on the vertical center, with side English, and with a perfectly level cue...there should be NO cue ball curve. In the same situation but with an elevated cue, will there be more CURVE with high English or low English?

Note: a perfectly level cue is possible with a very large table and is used here only as an example for a reference point.
Click to expand...

Well, if I had to guess, it would be more curve with the high english, because the cueball tends to get trapped underneath the tip, like a full masse. With the low english I'd think it more or less slips off, without that effect. With a normal degree of elevation, i'd think the effect (difference between high and low) would be miniscule, if it is noticable at all.
 
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Cornerman

Cornerman

Cue Author...Sometimes
Gold Member
Silver Member
Tennesseejoe said:
If you hit the cue ball on the vertical center, with side English, and with a perfectly level cue...there should be NO cue ball curve. In the same situation but with an elevated cue, will there be more CURVE with high English or low English?

Note: a perfectly level cue is possible with a very large table and is used here only as an example for a reference point.
Click to expand...

If you can shoot with a perfectly level cue, then there would be no curve with sidespin, regardless of how high or low.

Warning: Physics to follow:

From a Physics point of view, and ignoring Bernoulli effects (which would be miniscule, considering the non-free state and low surface irregularities) , the vector of the force needs a Z component for there to be a "cross product" for that Coriolis to take effect. Without the Z component of force, then the force of the hit from the cue is in a parallel plane with the friction from cloth, and no cross product is there to create non-zero vector in another direction.

With even a slight downward Z component, and the force due to friction going in the opposite direction of the cue, then with right-hand english, you get a motion component to the right, and with left-hand you get a left motion component due to the Right Hand Rule (Physics/Calculus right hand rule). But only with that downward Z component. With an upward Z component, the resultant additional sideways motion is opposite: left motion with right-hand spin, right motion with left-hand spin.

Freddie <~~~ let's talk about rarefied air instead
 
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Tennesseejoe

Tennesseejoe

AzB Silver Member
Silver Member
Freddie, I thought you were correct however Gorramjayne seemed to disagree. Thanks for the response. Tennessee Joe.


Originally Posted by Gorramjayne View Post


And it's absolutely untrue that a level cue will result in no CB curve.. A level cue will delay the transfer of sidespin to the cloth and the onset of the curve, especially with firmer hits but its an inescapable conclusion of physics that the ball will curve unless its rotation is the same as its direction of travel. Even if you had magic frictionless cloth, the spinning ball would still curve just because of how a spinning body alters airflow over its surface. See: Magnus effect.






Cornerman said:
If you can shoot with a perfectly level cue, then there would be no curve with sidespin, regardless of how high or low.

Warning: Physics to follow:

From a Physics point of view, and ignoring Bernoulli effects, the vector of the force needs a Z component for there to be a "cross product" for that Coriolis to take effect. Without the Z component of force, then the force of the hit from the cue is in a parallel plane with the friction from cloth, and no cross product is there to create non-zero vector in another direction.

With even a slight downward Z component, and the force due to friction going in the opposite direction of the cue, then with right-hand english, you get a motion component to the right, and with left-hand you get a left motion component due to the Right Hand Rule (Physics/Calculus right hand rule). But only with that downward Z component. With an upward Z component, the resultant additional sideways motion is opposite: left motion with right-hand spin, right motion with left-hand spin.

Freddie <~~~ let's talk about rarefied air instead
Click to expand...
 
Cornerman

Cornerman

Cue Author...Sometimes
Gold Member
Silver Member
Tennesseejoe said:
Freddie, I thought you were correct however Gorramjayne seemed to disagree. Thanks for the response. Tennessee Joe.


Originally Posted by Gorramjayne View Post


And it's absolutely untrue that a level cue will result in no CB curve.. A level cue will delay the transfer of sidespin to the cloth and the onset of the curve, especially with firmer hits but its an inescapable conclusion of physics that the ball will curve unless its rotation is the same as its direction of travel. Even if you had magic frictionless cloth, the spinning ball would still curve just because of how a spinning body alters airflow over its surface. See: Magnus effect.
Click to expand...
I gather that Gorramjayne is describing spinning balls in the air, like baseballs, which require stitching and Bernoulli for sideways motion. Neither of these are the case in pool.

It's a good thing this was hashed out decades ago, but I'm sure "new" material could be added to Dr. Dave's site. Would it be worth it to actually do the calculations just to see if the Magnus effect (Bernoulli effect, but specific to rotating spheres in linear motion through a fluid) is anywhere near significant to consider?

I would think that the force from the Bernoulli effect wouldn't be able to overcome the weight of the cue ball on the table. Simply shooting upward with english on an elevated cue ball (put in on a piece of chalk on the rail) should tell you all you need to know. It curves the opposite way, and no Magnus effect would overcome that. So, if hitting downward with right english curves the cueball to the right, and hitting upwards with right english curves a ball to the LEFT, then let's make a guess where the transition point is where there's no curving.
 
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iusedtoberich

iusedtoberich

AzB Silver Member
Silver Member
In my low B player experience, with the cue stick level being typical for the 3 below shots, the CB:

High outside: curves most
Middle outside: curves least
Low outside: curves middle amount
 
A

anbukev

AzB Silver Member
Silver Member
iusedtoberich said:
In my low B player experience, with the cue stick level being typical for the 3 below shots, the CB:

High outside: curves most
Middleton outside: curves least
Low outside: curves middle amount
Click to expand...

I'm thinking if hit with the same amount of speed:
Least
Baseline (betweener)
Most
 
Cornerman

Cornerman

Cue Author...Sometimes
Gold Member
Silver Member
iusedtoberich said:
In my low B player experience, with the cue stick level being typical for the 3 below shots, the CB:

High outside: curves most
Middle outside: curves least
Low outside: curves middle amount
Click to expand...

From my point of view, you still need a cue angle for the cue all to curve, and that in the same order, I observe that the higher the enlglish, the quicker it starts to curve. The lower the English, the longer the delay before curving, with all other thing equal (angle, speed, offset).

Quicker
Baseline
Less Quick
 
R

RussPrince

AzB Silver Member
Silver Member
think of curve like draw. it doesn't last very long. how much you get depends on how low/out the tip is to the cueball. remember a masse shot is applying a screw/diagonal action to the cueball so it doesn't last very long before friction eliminates it completely. the best types of masse shots (i.e. most consistent and predictable) are very short small angle changing masse shots.
 
sbpoolleague

sbpoolleague

AzB Silver Member
Silver Member
Whichever stroke imparts cue ball spin whose X component (with relation to the line of shot) of the axis of rotation is maximized. The X axis is tangent to the line of the shot, the Y axis IS the line of the shot, and the Z axis is pointing straight up in the air.

Imagine you could stroke the cue ball and magically have it spin but stay in place. Now imagine the blue cloth has ink that comes off on the cue ball. The ink will appear in a circle on the cue ball. The size of the circle will determine how much cue ball curve there is.

With a level cue, center left (or right) hit, the cue ball will spin like a top, and the blue circle will be so small that it should look like a dot. Near zero cue ball curve.

Now try and visualize what you would need to do to make the blue circle really big. THAT is the angle / location of hit that will maximize cue ball curve.
 
justadub

justadub

Rattling corners nightly
Silver Member
Cornerman said:
I gather that Gorramjayne is describing spinning balls in the air, like baseballs, which require stitching and Bernoulli for sideways motion. Neither of these are the case in pool.

It's a good thing this was hashed out decades ago, but I'm sure "new" material could be added to Dr. Dave's site. Would it be worth it to actually do the calculations just to see if the Magnus effect (Bernoulli effect, but specific to rotating spheres in linear motion through a fluid) is anywhere near significant to consider?

I would think that the force from the Bernoulli effect wouldn't be able to overcome the weight of the cue ball on the table. Simply shooting upward with english on an elevated cue ball (put in on a piece of chalk on the rail) should tell you all you need to know. It curves the opposite way, and no Magnus effect would overcome that. So, if hitting downward with right english curves the cueball to the right, and hitting upwards with right english curves a ball to the LEFT, then let's make a guess where the transition point is where there's no curving.
Click to expand...

Oh, you didn't go all Bernoulli on him, did you? :eek::eek::eek::eek:

<------has no idea what any of that means. :p but I'll trust that Cornerman is right
 
G

Gorramjayne

AzB Silver Member
Silver Member
Cornerman said:
If you can shoot with a perfectly level cue, then there would be no curve with sidespin, regardless of how high or low.

Warning: Physics to follow:

From a Physics point of view, and ignoring Bernoulli effects (which would be miniscule, considering the non-free state and low surface irregularities) , the vector of the force needs a Z component for there to be a "cross product" for that Coriolis to take effect. Without the Z component of force, then the force of the hit from the cue is in a parallel plane with the friction from cloth, and no cross product is there to create non-zero vector in another direction.

With even a slight downward Z component, and the force due to friction going in the opposite direction of the cue, then with right-hand english, you get a motion component to the right, and with left-hand you get a left motion component due to the Right Hand Rule (Physics/Calculus right hand rule). But only with that downward Z component. With an upward Z component, the resultant additional sideways motion is opposite: left motion with right-hand spin, right motion with left-hand spin.

Freddie <~~~ let's talk about rarefied air instead
Click to expand...

Forgive me if I'm wrong here, but while the force vector you initially exert on the CB in the case of a level cue would not directly induce spin on an axis that is not parallel or perpendicular to the direction of CB travel for as long as the cue is applying force, the CB will, however, as it moves over the cloth, continually shift its axis of rotation because of a friction vector. (In lay terms we say the ball has sidespin and develops then loses natural roll from the cloth, but by Euler's theorem any object rotating around a fixed point like a spinning ball has but one rotation about a single axis -- in our case the resistance of the cloth is a vector along the surface of the ball in the opposite direction of travel and this vector continually shifts the axis of rotation as the CB goes along)

Sure curve is negligible with a level cue and a firm shot (hard for the CB to curve too much when it is partially sliding) and a high degree of sidepsin will tend to stabilize the rotation making the ball travel a little bit like a spinning top/dreidel whathaveyou, but eventually the cloth friction will shift the axis of rotation and the ball will develop roll, and rolling CB with will curve because of sidespin.

Try playing snooker sometime and hit a table-length shot with a level cue with maximum side spin. Especially if you play the shot at pocket speed, you'll miss the ball entirely.
 
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Cornerman

Cornerman

Cue Author...Sometimes
Gold Member
Silver Member
Gorramjayne said:
Forgive me if I'm wrong here, but while the force vector you initially exert on the CB in the case of a level cue would not directly induce spin on an axis that is not parallel or perpendicular to the direction of CB travel for as long as the cue is applying force, the CB will, however, as it moves over the cloth, continually shift its axis of rotation because of a friction vector. (In lay terms we say the ball has sidespin and develops then loses natural roll from the cloth, but by Euler's theorem any object rotating around a fixed point like a spinning ball has but one rotation about a single axis -- in our case the resistance of the cloth is a vector along the surface of the ball in the opposite direction of travel and this vector continually shifts the axis of rotation as the CB goes along)

Sure curve is negligible with a level cue and a firm shot (hard for the CB to curve too much when it is partially sliding) and a high degree of sidepsin will tend to stabilize the rotation making the ball travel a little bit like a spinning top/dreidel whathaveyou, but eventually the cloth friction will shift the axis of rotation and the ball will develop roll, and rolling CB with will curve because of sidespin.

Try playing snooker sometime and hit a table-length shot with a level cue with maximum side spin. Especially if you play the shot at pocket speed, you'll miss the ball entirely.
Click to expand...
If you draw your free body diagram, you'll see what's happening.

Let's make sure we're still talking about theoretically being able to shoot with a dead-level cue, which is what the OP was asking, and he qualified the question understanding the difficulties of actually shooting dead-level.

Again, if you shoot upwards, it's easy to see that the cueball will have the OPPOSITE curve (physics agrees with this by torque and the righ-hand rule). Try to make sense of that on your snooker table example. You'll see quite quickly, as I assume you know something about basic physics, that if it curves the opposite direction with an upward stroke vs the downward stroke, then that means somewhere there's an angle of cue that creates no swerve, given the same amount of offset. It stands to reason that this "somewhere" is at dead-level.

Freddie <~~~ no idea what Euler has to do with this
 
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