Cue ball and Object ball travel.

Pidge said:
When you start thinking about speed control in such a structured manner its a recipe for disaster. If you have taken the time to develop a stroke that makes the cue ball travel x number of diamonds then you are capable of just getting down and making the cue ball go pretty close to where you want. When standing you should be thinking about position, how hard the shot needs to be hit. This goes for safety play also. Then when you are down don't think about it. Your brain is smart, and even though you may not have played for years it will calculate the required stroke if your brain has given you the correct information.

Now, that being said I would assume...

For a 1/2 ball hit shooting with stun - 50% of the energy will be transferred to the object ball and the cue ball will keep the other 50%.

If there were no rails on a table and just an infinite playing surface and you hit the shot at a speed that would travel 10 diamonds without contacting a ball, then a half ball hit would make the OB travel a distance of 5 diamonds from impact, and the CB (if it had stun) travel 5 diamonds also. All this is with the CB and OB very close to each other to start with. The further the distance between the two the more energy the CB loses so it becomes quite difficult to work out what % of energy the CB will have upon contact. This is why like I say, there are some systems for this I'm sure. But its best to just get down and play. Eventually everyone's speed control improves.
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That's not true, when you hit 50% ball, 50% of translation energy is transfered, but that is not 50% of speed because ec=0.5*ball_mass*speed^2. Dividing ec by 2 doesn't divide speed by 2, but for the square root of 2, 1.4 . So if you shot with a 10 diamond speed, if the ball hits another ball they will travel 7 diamonds each. Looks like it isn't that easy :)
 
frigopie said:
That's not true, when you hit 50% ball, 50% of translation energy is transfered, but that is not 50% of speed because ec=0.5*ball_mass*speed^2. Dividing ec by 2 doesn't divide speed by 2, but for the square root of 2, 1.4 . So if you shot with a 10 diamond speed, if the ball hits another ball they will travel 7 diamonds each. Looks like it isn't that easy :)
Click to expand...

You're right about energy being proportional to speed^2, but you're wrong about the 7 diamonds, because the distance the ball rolls before stopping is also proportional to speed^2.

Your greater point seems to be that the math gets complicated quickly, and that's quite true. While I do believe there's some value in knowing the reference facts Bob Jewett mentioned as starting points, I don't believe there's really any value in doing actual calculation at the table, or even in knowing the necessary formulae that would allow one to calculate.

-Andrew
 
Andrew Manning said:
You're right about energy being proportional to speed^2, but you're wrong about the 7 diamonds, because the distance the ball rolls before stopping is also proportional to speed^2.

Your greater point seems to be that the math gets complicated quickly, and that's quite true. While I do believe there's some value in knowing the reference facts Bob Jewett mentioned as starting points, I don't believe there's really any value in doing actual calculation at the table, or even in knowing the necessary formulae that would allow one to calculate.

-Andrew
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sure, I was too adventurous to put the numbers without making the calculations :)
 
frigopie said:
That's not true, when you hit 50% ball, 50% of translation energy is transfered, but that is not 50% of speed because ec=0.5*ball_mass*speed^2. Dividing ec by 2 doesn't divide speed by 2, but for the square root of 2, 1.4 . So if you shot with a 10 diamond speed, if the ball hits another ball they will travel 7 diamonds each. Looks like it isn't that easy :)
Click to expand...

Actually, a half ball hit doesn't equate to half the energy dispersion. The object ball acquires more of the force than the cue ball retains. It is more of a cut to see an equal dispersion.
 
frigopie said:
That's not true, when you hit 50% ball, 50% of translation energy is transfered, but that is not 50% of speed because ec=0.5*ball_mass*speed^2. Dividing ec by 2 doesn't divide speed by 2, but for the square root of 2, 1.4 . So if you shot with a 10 diamond speed, if the ball hits another ball they will travel 7 diamonds each. Looks like it isn't that easy :)
Click to expand...
Ha thanks for the lesson! Your post points out the reason no average pool player uses a speed system though...its damn confusing!
 
tonythetiger583 said:
I've pegged my stroke down to about 12 speeds which I've measured in terms of diamonds traveled (I know it depends on the speed of the table, but it at least gets me into the right ball park).

Is there a simple system to determine how far the cue ball will travel versus the object ball, depending on fullness of hit?

At the moment I've divided the object ball into 1 to 100% on each side, and kind of estimate from there.

Is there any simple and accurate way short of pulling out a calculator for each shot for me to figure out how far I want the object ball and cue ball to go? Even just giving a formula would be nice, since I'm not to sure on it, even with a calculator (terrible at math).

please and thanks.

Edit: Also how does draw and follow factor into all this.
And my speeds are:
Soft: 7 Diamonds, 9 diamonds, 11, 13,
Medium: 15,17,19,21
Hard: 23,25,27,29
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Are you using light grip or hard grip, or in between?
 
Careyp74 said:
Actually, a half ball hit doesn't equate to half the energy dispersion. The object ball acquires more of the force than the cue ball retains. It is more of a cut to see an equal dispersion.
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ummmm... I don't understand that
 
Pidge...While I agree with your basic assertion here, learning speed control through numerical assignments is the best and easiest way to get the process ingrained into "muscle memory". Human brains are infinitely hard-wired into using numerical scales and systems (we all use the same numerical scales for everything we do). If the brain learns that someone's swing has a nonrandom range of motion that is basically the same for most shots, the brain can train the biceps to swing the cue at a certain speed, because the start and finish position remain the same. I teach 10 speeds (lag to break, all using the exact same swing path, but varying degrees of forward acceleration. Absolutely I agree with you, that one cannot actually play while thinking about numerical levels. That said, when the range of motion is standard, the brain can easily be trained to deliver any of the 10 basic standard speeds, at will, on demand, under pressure. Others may disagree, but we have trained 1000's of students to do this successfully. :D

Scott Lee
http://poolknowledge.com

Pidge said:
Ha thanks for the lesson! Your post points out the reason no average pool player uses a speed system though...its damn confusing!
Click to expand...
 
naji said:
Are you using light grip or hard grip, or in between?
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It's in between.

I grip the cue and I have 3 speeds, soft, medium and hard.

Soft is essentially simply closing my hand without and force.
Medium is closing with a practiced amount of force, and Hard is closing my hand as hard as I can within reason and without involving any other part of my body.

For each speed, I'll let go of either my pinkie, ring finger, middle finger or index finger, as well as all the fingers behind them.

ex: Ring finger and pinkie finger, or middle finger, and ring, and pinkie.

The less fingers, the more I can pull back the cue.
 
victorl said:
I understand, but there are just so many different shots that it would be impossible to remember all the speed numbers, and changing the cut angle just a few degrees completely changes where the balls end up and how far they go... If you have an experienced player by your side to analyze the shots and tell you how hard to hit them, that might work... but honestly trying to figuring out shot speed just through calculations instead of playing experience is kind of counter-productive in that you are spending time and energy on calculations when you could be using that effort to develop a feel for the shots. (Just my opinion, though)

Dr. Dave's site (http://billiards.colostate.edu) has lots of resources, and this article in particular might be of interest to you.
http://billiards.colostate.edu/bd_articles/2009/march09.pdf

Good luck, and I hope you find something that works for you.
Click to expand...
... and more info and resources dealing this topic can be found here:

ball speeds and travel distances

Enjoy,
Dave
 
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