Squirt. End Mass and Cue Flexibility.

[Corwyn_8]

In other words the section of the cue 2" back from the tip moves further than the tip itself (in your diagram). How?

Is this TORQUE? Is the front end of the cue being ROTATED about its center of mass (clockwise in your diagram)? And that effect only having propagated a few inches down the shaft length at the time of you diagram? That makes a bit of sense, in that I can actually picture the force involved.

Thank you kindly.

 

[Jaden]

Here you go.

The picture on the bottom is what happens during the first part of contact. As the cue makes contact off center, the tip bends inward and force is exerted on the shaft as shown by the curving line from the center of mass of the ball.

As the ball starts to move forward, it begins accelerating while the mass of the ball causes the cue to decelerate. As the ball moves away from the tip, it begins to release the stored kinetic energy in the shaft and it reacts in the oppsite direction releasing the stored kinetic energy by moving outward as shown in the top diagram. The mass of the ball isn't actively pushing the shaft ANYWHERE. It is the release of the stored kinetic energy in the shaft by the ball's mass movign away and ceasing to act on the shaft that moves the shaft away from the ball outward.

Jaden

 

[dr_dave]

Is the front end of the cue being ROTATED about its center of mass (clockwise in your diagram)? And that effect only having propagated a few inches down the shaft length at the time of your diagram? That makes a bit of sense, in that I can actually picture the force involved.

Here's the original diagram:

and here's a new diagram and explanation from the squirt endmass and stiffness effects resource page that helps explain the effects of the total force (the combination of the forward force in the direction of the cue and the sideways force that causes squirt):

The force between the tip and CB acts equal and opposite on each object. The CB speed is in the direction of this total force. The CB spin is created since the force's line of action acts at a tip offset relative to CB center, creating a moment or torque. The equal and opposite force on the cue tip also acts off-center on the end of the shaft, creating a bending moment or torque. This is what causes the end of the shaft to flex.

I hope that helps,
Dave

 

[Jal]

Is this TORQUE? Is the front end of the cue being ROTATED about its center of mass (clockwise in your diagram)? And that effect only having propagated a few inches down the shaft length at the time of you diagram? That makes a bit of sense, in that I can actually picture the force involved.

Dr. Dave beat me to it (go figure), but rather than having this just sit on my hard drive, I thought I should do something with it (no, not that Jaden). At any rate, I think your description is correct.



Of course, the location of the center of mass of the tip segment is an evolving item. This would be a snapshot.

Between yourself and Dr. Dave, I believe your earlier question has been answered, but just to note that the direction of the force on the cue is such that the entire tip segment is pushed laterally away from the cueball.

Jim

 

[Jaden]

it can't be pushed out except in a miscue...

Dr. Dave beat me to it (go figure), but rather than having this just sit on my hard drive, I thought I should do something with it (no, not that Jaden). At any rate, I think your description is correct.

View attachment 411301

Of course, the location of the center of mass of the tip segment is an evolving item. This would be a snapshot.

Between yourself and Dr. Dave, I believe your earlier question has been answered, but just to note that the direction of the force on the cue is such that the entire tip segment is pushed laterally away from the cueball.

Jim

The diagram is showing the force involved correctly here. What seems to be alluding you guys is that so long as there is friction and grip between the tip and the ball there can be no pushing laterally outward. Instead, the tension that is built up in the shaft temporarily bows the shaft outward so that as the ball accelerates away from the tip, the bowed tension in the shaft is released and the front of the shaft and tip travels laterally away from the ball due to the release of this tension.

The only way that the mass of the ball would be PUSHING the tip and shaft outwards is with a miscue when the friction and grip ceases...

Jaden

 

[Jal]

The diagram is showing the force involved correctly here.

You say it shows the force correctly, yet the force is shown pushing outward (upward in the diagram)? Sure, it's mostly pointing down the shaft, but there's a clear outward (lateral) component.

What seems to be alluding you guys is that so long as there is friction and grip between the tip and the ball there can be no pushing laterally outward.

What happens when the ball starts spinning? How does the tip follow the surface without slipping and without moving laterally outward?

From what you've stated earlier, I think I know what your answers to those questions will be, but I'd like to hear them again, just to be sure.

Jim

 

[Jaden]

the ball is acceletating away

You say it shows the force correctly, yet the force is shown pushing outward (upward in the diagram)? Sure, it's mostly pointing down the shaft, but there's a clear outward (lateral) component.

What happens when the ball starts spinning? How does the tip follow the surface without slipping and without moving laterally outward?

From what you've stated earlier, I think I know what your answers to those questions will be, but I'd like to hear them again, just to be sure.

Jim

The ball is accelerating AWAY from the tip when the ball starts spinning.

It DOES move laterally outward at that point, I never said it didn't..

It's moving outward due to the stored kinetic energy in the shaft though, not from a force being exerted on it from the mass of the ball. That force has already been exerted on the shaft at that point.

So it is inaccurate to say that the ball is pushing the shaft outward. It has already finished pushing on the shaft, and that energy is stored in the shaft the way that a bow has stored energy in it from pulling the string backward.

The ball beginning to accelerate away from the tip is like releasing the string on a bow, the stored energy in the wood of the bow is released and the bow unbows pulling the string forward.

In this case, the ball begins to accelerate away from the tip allowing the tension in the shaft to release in the opposite direction and it then moves away from the ball laterally.

Jaden

 

[skankhammer]

This thread is making my head hurt...

 

[Jaden]

here's an experiment you can do that shows this...

Take a cue and press against a wall or solid surface with just one side of the tip touching.

as you press it you'll see that the shaft bows outward. That's the exact same thing it does when it makes contact with the ball. It is that bowing outward that pulls the shaft outward as the ball accelerates away from the tip and the mass that is preventing the shaft from moving outward moves away.

Jaden

 

[Jal]

The ball is accelerating AWAY from the tip when the ball starts spinning.

It DOES move laterally outward at that point, I never said it didn't..

It's moving outward due to the stored kinetic energy in the shaft though, not from a force being exerted on it from the mass of the ball. That force has already been exerted on the shaft at that point.

So it is inaccurate to say that the ball is pushing the shaft outward. It has already finished pushing on the shaft, and that energy is stored in the shaft the way that a bow has stored energy in it from pulling the string backward.

The ball beginning to accelerate away from the tip is like releasing the string on a bow, the stored energy in the wood of the bow is released and the bow unbows pulling the string forward.

In this case, the ball begins to accelerate away from the tip allowing the tension in the shaft to release in the opposite direction and it then moves away from the ball laterally.

Jaden

But there's a problem with your scenario. The reason there's a problem lies with the answer to the question "Why does the force on the cueball point straight ahead (approximately)?" I don't have any more time tonight to get into it. If someone else doesn't provide the gory details, I'll try to do it tomorrow. The short answer is that's the only way the movement of the tip can track the movement of the surface of the cueball, which it does of course, when there is no slippage (no miscue).

Jim

 

[LAMas]

The ball is accelerating AWAY from the tip when the ball starts spinning.

It DOES move laterally outward at that point, I never said it didn't..

It's moving outward due to the stored kinetic energy in the shaft though, not from a force being exerted on it from the mass of the ball. That force has already been exerted on the shaft at that point.

So it is inaccurate to say that the ball is pushing the shaft outward. It has already finished pushing on the shaft, and that energy is stored in the shaft the way that a bow has stored energy in it from pulling the string backward.

The ball beginning to accelerate away from the tip is like releasing the string on a bow, the stored energy in the wood of the bow is released and the bow unbows pulling the string forward.

In this case, the ball begins to accelerate away from the tip allowing the tension in the shaft to release in the opposite direction and it then moves away from the ball laterally.

Jaden

The tip and the front of the shaft like bounces off of the mass of the CB at impact.

A shaft in motion tends to stay in motion until...its tensile and compressive strength maxima is reached and recovery occurs.

https://upload.wikimedia.org/wikipedia/commons/6/68/Beam_mode_1.gif

Be well

 

[dr_dave]

The diagram is showing the force involved correctly here.

I'm glad you agree with this, because everything else presented on my resource pages is consistent with this force direction.

so long as there is friction and grip between the tip and the ball there can be no pushing laterally outward.

This is where your error lies. Look again at the diagrams:

In the top diagram, the only way the CB can be deflected (squirted) down (in the diagram) is if the tip is pushing it down (in the diagram). If the tip is pushing the CB down (in the diagram), then the CB must also be pushing back on the tip up (in the diagram), as shown by the equal and opposite S_imp arrows. This is why the end of the shaft gains momentum (mv_end) that causes it to flex out. This flex out continues after tip release due to the momentum imparted during tip contact. Again, all of this stuff is described and illustrated in great detail in the following resource pages:

what causes squirt

squirt endmass and stiffness effects

In the bottom diagram, notice how the force from the tip pushes in the direction the CB heads (i.e., the force arrow is parallel to the speed arrow). This force has two components. One component acts to the right (in the diagram) on the CB and to the left (in the diagram) on the tip. This component is what pushes the CB forward in the line of aim of the shot, and causes the end of the shaft to flex as shown in the bottom diagram (because the force acts off center on the tip). The other force component acts down (in the diagram) on the CB and up (in the diagram) on the tip. This component is what causes CB deflection (squirt) and causes the end of the shaft to gain momentum (speed) away from the CB (up in the diagram) that causes the shaft to flex out. This outward flex starts during tip contact (as the CB rotates during contact and pushes the tip away, as described and illustrated on the what causes squirt resource page) and continues after tip release due to the momentum imparted during tip contact.

Now that you agree with the direction of the force acting equal and opposite between the tip and CB, I think you might better relate to the physics documented, illustrated, analyzed, and demonstrated on the resource pages. Please check them out again keeping the force direction (and force components) in mind.

I hope this helps,
Dave

 

[dr_dave]

it is inaccurate to say that the ball is pushing the shaft outward.

Again, you are wrong on this point. The evidence is overwhelming, and the physics theory is very simple and straightforward.

energy is stored in the shaft the way that a bow has stored energy in it from pulling the string backward.

The ball beginning to accelerate away from the tip is like releasing the string on a bow, the stored energy in the wood of the bow is released and the bow unbows pulling the string forward.

In this case, the ball begins to accelerate away from the tip allowing the tension in the shaft to release in the opposite direction and it then moves away from the ball laterally.

The flex and stored energy in the shaft is caused by the force between the tip and CB, not the other way around. This is an important point. Some of the stored energy is returned during tip contact (while the force between the tip and CB is still acting); but some (probably most) of the energy remains in the shaft after tip release, causing the vibrations evident in the videos on the cue vibration resource page.

I hope that helps,
Dave

 

[Jaden]

Sorry again you're missing the fact that the ball is pulling away from the tip.

But there's a problem with your scenario. The reason there's a problem lies with the answer to the question "Why does the force on the cueball point straight ahead (approximately)?" I don't have any more time tonight to get into it. If someone else doesn't provide the gory details, I'll try to do it tomorrow. The short answer is that's the only way the movement of the tip can track the movement of the surface of the cueball, which it does of course, when there is no slippage (no miscue).

Jim

No, because the ball is pulling away from the tip and the tip is decompressing, which releases some of the mass of the ball pressing back against the cue. There doesn't have to be any slippage for the force on the shaft to decrease and the stored energy in the shaft to release allowing the reaction that forces the shaft to allow outward motion to occur.

There only had to be enough force released by the ball pulling away from the tip for the stored energy to cause the shaft to react by bending outward

Jaden

 

[Jaden]

I'm sorry but it can't.

Again, you are wrong on this point. The evidence is overwhelming, and the physics theory is very simple and straightforward.

The flex and stored energy in the shaft is caused by the force between the tip and CB, not the other way around. This is an important point. Some of the stored energy is returned during tip contact (while the force between the tip and CB is still acting); but some (probably most) of the energy remains in the shaft after tip release, causing the vibrations evident in the videos on the cue vibration resource page.

I hope that helps,
Dave

I think you need to look at those videos again.

When the shaft starts to move outward, the tip has already started to decompress,which means the ball has started to accelerate away from the shaft.

Please show me the physics that allows an object accelerating away from another object to act on the object it is accelerating away from...


Again nothing about the additional vibration of the shaft after the tip completely loses contact precludes the initial outward movement from being caused by the same stored energy,butt the fact that the ball has begun to accelerate away from the tip before contact ceases and the shaft starts moving outward does preclude the ball directly acting on the tip or shaft at that point

Jaden

p.s. you love to say the evidence is overwhelming without providing any. I HAVE provided evidence. The evidence of your own videos.

The shaft doesn't move outward until the tip starts to decompress. That means that the ball is accelerating away from the tip, BEFORE the shaft moves outward. So answer this question...

Does physics allow for an object accelerating away from another object to directly act on that object?

 

[Jaden]

wow...

I'm glad you agree with this, because everything else presented on my resource pages is consistent with this force direction.

This is where your error lies. Look again at the diagrams:

In the top diagram, the only way the CB can be deflected (squirted) down (in the diagram) is if the tip is pushing it down (in the diagram). If the tip is pushing the CB down (in the diagram), then the CB must also be pushing back on the tip up (in the diagram), as shown by the equal and opposite S_imp arrows. This is why the end of the shaft gains momentum (mv_end) that causes it to flex out. This flex out continues after tip release due to the momentum imparted during tip contact. Again, all of this stuff is described and illustrated in great detail in the following resource pages:

what causes squirt

squirt endmass and stiffness effects

In the bottom diagram, notice how the force from the tip pushes in the direction the CB heads (i.e., the force arrow is parallel to the speed arrow). This force has two components. One component acts to the right (in the diagram) on the CB and to the left (in the diagram) on the tip. This component is what pushes the CB forward in the line of aim of the shot, and causes the end of the shaft to flex as shown in the bottom diagram (because the force acts off center on the tip). The other force component acts down (in the diagram) on the CB and up (in the diagram) on the tip. This component is what causes CB deflection (squirt) and causes the end of the shaft to gain momentum (speed) away from the CB (up in the diagram) that causes the shaft to flex out. This outward flex starts during tip contact (as the CB rotates during contact and pushes the tip away, as described and illustrated on the what causes squirt resource page) and continues after tip release due to the momentum imparted during tip contact.

Now that you agree with the direction of the force acting equal and opposite between the tip and CB, I think you might better relate to the physics documented, illustrated, analyzed, and demonstrated on the resource pages. Please check them out again keeping the force direction (and force components) in mind.

I hope this helps,
Dave

yes, there is an equal and opposite force acting on the tip and shaft, but the friction and grip force prevents it from pushing the tip/shaft outward. It isn't until the ball begins to accelerate away that the tip/shaft begins to move outward. Instead, this equal and opposite force bows the shaft outward creating stored kinetic energy that is released once the ball begins to accelerate away from the tip/shaft.

Yes this occurs before contact ceases, but that is only because the tip is elastic and compressed and the decompression of the tip allows it to maintain contact as the ball begins to accelerate away. However, since the ball IS accelerating away from the tip/shaft, it can't possibly be directly acting on the tip/shaft.

Jaden

 

[ENGLISH!]

How about imagining a very high surface friction metallic cue ball being held in place by an extremely powerful electromagnetism?

Then we have a very soft super high friction tip & a very flexible shaft.

We place the tip & the shaft off center on the metal cue ball & apply force down its linear line.

The shaft loads & bows out with the tip end turning in toward the center of the ball.

THEN... the switch is flipped & the electromagnetism it turned off which releases the metal cue ball.

What causes the metal cue ball to move?

It's the kinetic energy that has been stored in the deformed tip & shaft.

Perhaps there is some confusion by saying that the CB "pushes" instead of saying that it resists the force being applied to it.

Semantics in a sense.

IF there was no flex or bend in the shaft, then the interpretations would be different & would need to be different.

The collision of the pliable material striking the cue ball is not exactly that same as the collision of one solid ridged ball hitting another solid ridged ball off center.

The moving ball picks up rotation from the collision & delivers rotation to the ball with which it collides.

If the object ball was fixed & immovable the outcome would be different.

If the cue ball where fixed & immovable the outcome of the shaft & tip hitting it would also be different.

The tip would compress & the shaft would flex & load & the friction overcome & the tip would slip & the shaft would recover & slide off, deflect, to & past the outer edge of the immovable resisting ball.

Or if the friction & force where great enough perhaps the shaft would shatter. (Some Predator shafts have done so.)

But... the cue ball is not immovable & the shaft & tip are not like the more solid & ridged ball colliding with another solid & ridged ball.

The tip & the shaft are 'alive' with pliability.

From a players perspective, or at least mine, it's the tip & shaft 'grabbing' the Cue Ball & it's the tip & shaft that is spinning the ball as it launches it away.

That's also the 'feeling' when a swipe stroke is applied to the ball.

It's not a 'feeling' of the tip & shaft 'bouncing' off or deflecting off of the ball...from a collision

at least not when the timing in right.

I have two different mind sets when I am spinning a ball for spin purposes & when I am squirting a ball for squirt purposes. Hell, I think my timing is different for both of those different intended purposes.

In a properly timed golf swing the shaft is actually bent forward when it contacts the ball. The shaft is loaded & bent backwards by the forward swing but then it is released & the shaft recovers & then bends forward as it hits the ball.

Many amateurs do not get that forward bend & power from the shaft as they hang on & never release the backward bend until after the ball is struck, if at all.

This is just intended as some food for thought for anyone interested.

It is not intended as any argument for or against anyone.

 

[dr_dave]

yes, there is an equal and opposite force acting on the tip and shaft, but the friction and grip force prevents it from pushing the tip/shaft outward. It isn't until the ball begins to accelerate away that the tip/shaft begins to move outward.

Yes this occurs before contact ceases, but that is only because the tip is elastic and compressed and the decompression of the tip allows it to maintain contact as the ball begins to accelerate away. However, since the ball IS accelerating away from the tip/shaft, it can't possibly be directly acting on the tip/shaft.

Jaden,

I've done my best to try to explain and illustrate what is going on, but it seems like you are un-sway-able in your views and interpretations. I know you might think the same about my viewpoints, but be aware that my explanations are consistent with physics theory and also intuitively explain what is happening. Also be aware that I have been studying and teaching this sort of stuff at a high level for over 30 years, so I'm not just "shooting from the hip" or trying to invent explanations.

Regards,
Dave

 

[Jaden]

Jaden,

I've done my best to try to explain and illustrate what is going on, but it seems like you are un-sway-able in your views and interpretations. I know you might think the same about my viewpoints, but be aware that my explanations are consistent with physics theory and also intuitively explain what is happening. Also be aware that I have been studying and teaching this sort of stuff at a high level for over 30 years, so I'm not just "shooting from the hip" or trying to invent explanations.

Regards,
Dave

I know you've done your best, and you act like it's my unwillingness to compromise to your viewpoint or inability to understand that's preventing me from "seeing the truth" lol.

Here is some deductive reasoning coming to my conclusion. I am fully open to you showing the premises to be incorrect and therefore the conclusion to be incorrect, but the reasoning is absolutely correct, so, unless you can show the premises to be incorrect.....

premise 1) the ball is accelerating away from the tip/shaft before the tip/shaft moves laterally away from the initial line of travel which is evident from high speed video because the tip is decompressing prior to lateral tip/shaft movement.

premise 2) an object accelerating away from another object cannot directly act on the object it is accelerating away from.

Conclusion) because a ball struck off center is accelerating away from the tip/shaft that imparted the force to accelerate the ball away from it, the ball cannot possibly be directly acting on tip/shaft in any way, especially pushing it laterally away from the ball.

The reasoning is sound. I know you'll try to come up with some other convoluted means pointing back to your own materials why it can't be right without ever addressing the actual premises.

So basically I'm putting these up so that the people who are reading this can go look at the materials themselves and see that these premises are correct.

You see, I don't play the, I"m an authority and everyone who matters agrees with me, game.

I put actual, understandable information out there that people can determine for themselves the accuracy there of.

It's funny, cause in all of this argument, which really isn't even an argument.

It's consisted of me providing explanations of why something must be a certain way and others stating, "no you're wrong because we say so. See, I've already stated how it REALLY works." Yeah but you haven't shown WHY it works that way and haven't really provided any evidence that that is how it works, except fallacy stating physics agrees with me.

That's not an argument, that's an appeal to authority. I could've said the same thing, "no, the physics agrees with me". I know you are but what am I.

Your condescending attitude and unwillingness to address my points with nothing more than, "that's the way it is", shows that you are just protecting your ego.

So again, show how any of my premises are wrong...because the logic is infallible...

Jaden

 

[john coloccia]

I know you've done your best, and you act like it's my unwillingness to compromise to your viewpoint or inability to understand that's preventing me from "seeing the truth" lol.

Here is some deductive reasoning coming to my conclusion. I am fully open to you showing the premises to be incorrect and therefore the conclusion to be incorrect, but the reasoning is absolutely correct, so, unless you can show the premises to be incorrect.....

premise 1) the ball is accelerating away from the tip/shaft before the tip/shaft moves laterally away from the initial line of travel which is evident from high speed video because the tip is decompressing prior to lateral tip/shaft movement.

premise 2) an object accelerating away from another object cannot directly act on the object it is accelerating away from.

Conclusion) because a ball struck off center is accelerating away from the tip/shaft that imparted the force to accelerate the ball away from it, the ball cannot possibly be directly acting on tip/shaft in any way, especially pushing it laterally away from the ball.

The reasoning is sound. I know you'll try to come up with some other convoluted means pointing back to your own materials why it can't be right without ever addressing the actual premises.

So basically I'm putting these up so that the people who are reading this can go look at the materials themselves and see that these premises are correct.

You see, I don't play the, I"m an authority and everyone who matters agrees with me, game.

I put actual, understandable information out there that people can determine for themselves the accuracy there of.

It's funny, cause in all of this argument, which really isn't even an argument.

It's consisted of me providing explanations of why something must be a certain way and others stating, "no you're wrong because we say so. See, I've already stated how it REALLY works." Yeah but you haven't shown WHY it works that way and haven't really provided any evidence that that is how it works, except fallacy stating physics agrees with me.

That's not an argument, that's an appeal to authority. I could've said the same thing, "no, the physics agrees with me". I know you are but what am I.

Your condescending attitude and unwillingness to address my points with nothing more than, "that's the way it is", shows that you are just protecting your ego.

So again, show how any of my premises are wrong...because the logic is infallible...

Jaden

Premise 1 is wrong. The cue ball can't accelerate away from the shaft unless something is pushing on it, i.e. the shaft. In fact, it starts to decelerate due to friction immediately after the shafts stops pushing on it. It's the shaft that decelerates, mostly due to hitting the cue ball. Said another way, there's a transfer of momentum, one of those convenient quantities that is always conserved.