The Myth of Top Spin???

mikepage said:
No, most of the action is in the tip. Though if you cut the tip and ferrule off and hit the ball with wood, the wood would do the same thing.

And normally when people talk about "flex" of a cue they mean bending--and that bending energy is mostly lost. It's the compression along the stick that would be doing the action.
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Thanks for the clarification. But, now you've got me intrigued, because that goes against what I had understood to be the case. So, if you'd indulge me a little bit...

I thought I remembered hearing that the compression of the cue was what transferred most of the power, and that's why cues are made out of wood instead of metal or some other material. Are you saying that the compression of the stick is negligible, or just that it doesn't make as big of an impact as the compression of the tip? In other words, with the right tip/ferrule set up, could you get roughly the same performance out of a metal cue as you could out of a wood cue?
 
spoons said:
Thanks for the clarification. But, now you've got me intrigued, because that goes against what I had understood to be the case. So, if you'd indulge me a little bit...

I thought I remembered hearing that the compression of the cue was what transferred most of the power, and that's why cues are made out of wood instead of metal or some other material. Are you saying that the compression of the stick is negligible, or just that it doesn't make as big of an impact as the compression of the tip? In other words, with the right tip/ferrule set up, could you get roughly the same performance out of a metal cue as you could out of a wood cue?
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Only because I am up...supposedly working late...I think Mike and I are having trouble with your use of the word "compression" in regard to the CUE STICK.

The TIP compresses, but the shaft BENDS or "flexes" as Mike put it.

That bending is what Mike says detracts from the force applied to the CB just as would be the case if you hit the CB with a licorice stick.

In addition, the CB is gone before the stick "unbends" so there is no "spring action"...just the absorbtion of energy...like a shock absorber.

Sorry for chiming in...this is just my take on your question. Mike will be able to explain it more thoroughly/accurately than I.

Regards,
Jim
 
Hi. Maybe this will help...

If you hit the cue ball on top (bone of contention) with above medium strength and the cue ball has time to react to the stroke (at least from before half a table) with the object ball near the end rail (an inch away or less) -- after impact, the cue ball will spin forward against the end rail, bounce back, and again spin forward against the end rail again and again until the spin dies down. It is the spin that creates that motion and not forward momentum. With side-spin on top, this shot is often used in trick shots to make the cue ball find its way to a same end corner pocket from half the end rail after impact.

I call it top spin.

Incidentally, the shot is called "sputnik" here in Manila.
 
mikepage said:
8-baller is right.

The tip is storing energy like a spring does as it's compressed.

Halfway through the tip-ball contact , when the tip is fully compressed, the ball and stick are moving at the same speed. During the whole second half the ball is speeding up and the stick is slowing down. The tip is releasing it's stored energy during this part.

By the time the collision is over, the ball is going about 50% faster than the stick ever was.
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Mike. Help.

If I could learn to move my break cue at 28 MPH and have perfect contact, how fast does my cue ball travel??????? Thanks fellow Instructor....SPF=randyg
 
Jason Robichaud said:
CB would never travel past OB if it didn't. Must be easy to get the BCA instructor cards!
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I don't agree with Simpson, but I don't agee with what you say either. If it has just normal roll, no overspin, it will still follow. It will only not follow if it strikes with back spin or sliding with no spin.
 
randyg said:
Mike. Help.

If I could learn to move my break cue at 28 MPH and have perfect contact, how fast does my cue ball travel??????? Thanks fellow Instructor....SPF=randyg
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I don't know exactly. If your break cue is 18 OZ and the ball is 6 OZ, then conservation of energy and momentum suggests the cue ball will travel at 42 mph.

But this assumes a perfectly elastic collision (like a ball that bounces up to the height you dropped it from). In the real world it will be slower than this.

I'll take a guess: 38 mph
 
spoons said:
Thanks for the clarification. But, now you've got me intrigued, because that goes against what I had understood to be the case. So, if you'd indulge me a little bit...

I thought I remembered hearing that the compression of the cue was what transferred most of the power, and that's why cues are made out of wood instead of metal or some other material. Are you saying that the compression of the stick is negligible, or just that it doesn't make as big of an impact as the compression of the tip? In other words, with the right tip/ferrule set up, could you get roughly the same performance out of a metal cue as you could out of a wood cue?
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The energy in the wood is a little more complicated. The impact produces pressure waves in the wood that travel down the stick and back. The speed of these compression waves (sound) in maple is a little more than 4 meters per millisecond. So by the time the tip-ball collision is about half over, the ball has sensed the whole stick. At this point new compression energy in the stick is running into old compression energy, etc. Essentially all the energy in the ball and the compression of the tip has passed through the stick.

I think the performance of a metal cue of the same weight would be about the same.
 
interesting

Mike,

This is interesting. I have researched barrel harmonics in a rifle pretty thoroughly once upon a time, this was related to the lengthwise harmonics and the time the bullet was in the barrel. This is the first time I have read real information concerning time of tip contact and harmonics.

Assuming what you say is true, which I have no reason to doubt, that seems to indicate that many common assumptions concerning cue hit and it's importance are false.

Thanks,
Hu


mikepage said:
The energy in the wood is a little more complicated. The impact produces pressure waves in the wood that travel down the stick and back. The speed of these compression waves (sound) in maple is a little more than 4 meters per millisecond. So by the time the tip-ball collision is about half over, the ball has sensed the whole stick. At this point new compression energy in the stick is running into old compression energy, etc. Essentially all the energy in the ball and the compression of the tip has passed through the stick.

I think the performance of a metal cue of the same weight would be about the same.
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Southpaw said:
Doesnt the density of the object ball it contacts make a difference? If the object ball is heavier, wouldnt it absorb more than a lighter ball?

Southpaw
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(or object balls) I believe that is exactly why its harder to follow after contacting a greater mass, not only is the forward momentum absorbed but so is some of the rotational momentum.
 
ShootingArts said:
Mike,

This is interesting. I have researched barrel harmonics in a rifle pretty thoroughly once upon a time, this was related to the lengthwise harmonics and the time the bullet was in the barrel. This is the first time I have read real information concerning time of tip contact and harmonics.

Assuming what you say is true, which I have no reason to doubt, that seems to indicate that many common assumptions concerning cue hit and it's importance are false.

Thanks,
Hu
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That's interesting too. Which assumptions are you thinking of?

pj
chgo
 
Originally Posted by Southpaw
Doesnt the density of the object ball it contacts make a difference? If the object ball is heavier, wouldnt it absorb more than a lighter ball?

Southpaw
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(or object balls) I believe that is exactly why its harder to follow after contacting a greater mass, not only is the forward momentum absorbed but so is some of the rotational momentum.
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I don't think the OB's mass causes the CB to lose significant rotational momentum. I think the main factor in reducing the lighter CB's follow is that it rebounds a little before the follow spin takes effect - so the rebound distance is subtracted and the reverse momentum has to be overcome.

pj
chgo
 
Patrick Johnson said:
I don't think the OB's mass causes the CB to lose significant rotational momentum. I think the main factor in reducing the lighter CB's follow is that it rebounds a little before the follow spin takes effect - so the rebound distance is subtracted and the reverse momentum has to be overcome.

pj
chgo
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Yeah, I'm sure that plays into it also, but if you've ever force followed a secondary break shot into the rack in straight pool, at times you can actually see the cue ball sitting there overspinning like a race car peeling out with his front brakes on. :) Then, after parting the mass somewhat, the CB proceeds forward with what is left of the rotational momentum.
 
mikepage said:
The energy in the wood is a little more complicated. The impact produces pressure waves in the wood that travel down the stick and back. The speed of these compression waves (sound) in maple is a little more than 4 meters per millisecond. So by the time the tip-ball collision is about half over, the ball has sensed the whole stick. At this point new compression energy in the stick is running into old compression energy, etc. Essentially all the energy in the ball and the compression of the tip has passed through the stick.

I think the performance of a metal cue of the same weight would be about the same.
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I have no doubt that my grasp of terminology is a limitation here. Thanks for the info guys....I think I follow that, even though this is well beyond the physics I remember from college. (that education was money well spent :( )

How, if at all, does this relate to the after market shafts like the 314, OB-1, etc.? Meucci for example, has talked about "more power with less effort" for years, and I think I've seen other manufacturers make similar claims. Is there any merit to that, or is it just a marketing ploy?

Thanks again! I love this stuff....I just don't know enough to figure it out for myself :confused:
 
Patrick Johnson said:
Only at first. Jim usually manages to change what he "meant to say" to fit reality - it just takes several iterations to get there.

pj
chgo
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Well, you let us know when you decide to change what you meant to say when you said that the eyes are not held above a rifle barrel and that reasoned thought must be rational.



Thanks for all the laughs!

(-:
 
mbippus said:
It seems that if part of the cueball is moving backwards while moving forward that would mean the the cue ball is spinning faster than it is rolling. Which I thought Byrne said wasn't possible.
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I think he said it wasn't practical (rather than not possible) and gave a demo shot to test the idea.
 
.. THE COEFFICIENT OF FRICTION OF THE CUE-TIP ON THE CUE BALL MUST BE GREATER THAN THE COEFFICIENT OF FRICTION OF THE CLOTH ON THE CUEBALL. ...
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Someone else has probably pointed this out already, but this statement is false. I just wanted to make sure the error didn't go unchallenged.

In fact the coefficient of tip-ball friction seems to be about 1 and the ball-cloth friction seems to be about 0.2, but the ratio of those values has nothing to do with being able to get "excess" follow on the cue ball.
 
my 2 cents

I think on the break shot and many other force shots the cue ball is airborn and off the cloth so the friction that normally controls the ball's RPM is not a factor. The cue ball is like a flywheel spinning and while in the air, there is almost no friction to slow it down.
 
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