Questions regarding Duration of Contact between cueball and tip.

[sightline]

When the shaft strikes the cueball,

I heard that the tip only stay in tough with the cueball for 1/1000 second, is this true? Then why are we alway advised to follow through?

how long does the tip stay in contact with the cueball? a very small distance, halfway through the stroke or the entire stroke??

how do different speed strokes (soft, medium, fast) affect this?

For three cushion, the cueball is bigger and very heavy. does the contact duration change?

Thanks...

 

[Scott Lee]

sightline...You are correct that the dwell time between cuetip and CB is only 1/1000th of a second (about a quarter of an eyeblink), which means the CB leaves the tip literally as soon as it touches it. Nothing significantly changes that. This was proven by Bob Jewett and some others in the Jacksonville Project (which you can view online if you want). You are also correct that as far as physics go you don't have to "followthrough" more than contacting the CB. We don't teach a 'followthrough', as much as we teach finishing your stroke. The amount/distance you move the tip past the CB doesn't matter, but you can finish a stroke the easy way (naturally), or the hard way (huge extensive followthrough...which doesn't do anything to enhance the outcome of the shot). I believe in KISS.

Scott Lee
http://poolknowledge.com

 

[Tony_in_MD]

As far as why follow through in the first place. It is a more natural and predictable motion of the arm that you are trying to achieve. By swinging through the ball you are more apt to be accelerating the cue tip through the ball, then if you tried to stop the cuetip upon contact with the cueball. In fact I would bet that if someone made a effort to stop their cuetip upon contact with the ball, they would likely be slowing down prior to contact, in preparation to stop. This could wreck havoc on any consistency they would try to achieve, unless they played this way their entire life.

As far as your other questions regarding stroke speed and billiard balls, I don't know if anyone has measured that contact time with those variables. In my opinion, if they did, there would not be a lot of difference that would be meaningful or useful.

 

[Donny Lutz]

Value of follow-through

When the shaft strikes the cueball,

I heard that the tip only stay in tough with the cueball for 1/1000 second, is this true? Then why are we alway advised to follow through?

how long does the tip stay in contact with the cueball? a very small distance, halfway through the stroke or the entire stroke??

how do different speed strokes (soft, medium, fast) affect this?

For three cushion, the cueball is bigger and very heavy. does the contact duration change?

Thanks...

A pure and consistent follow-through helps in assuring an accurate hit on the CB. In this sense it's a training tool. It's also a way of assessing the accuracy of your stroke. If your follow-through is not consistent with your planned stroke, you will not likely be accurate with your hit on the CB. An accurate follow-through is proof that the cue was lined up properly prior to delivery.

It's why bowlers aim at a board (or an imaginary line across boards) rather than simply a spot on the lane. By following through ALONG a line, you have direction as well as target, though of course once the ball leaves your hand you have no more control of it. The same with pool. Whether your follow-through is two inches or two feet, it gives you direction as well as target.

Donny L
PBIA/ACS Instructor

 

[Bob Jewett]

When the shaft strikes the cueball,

I heard that the tip only stay in tough with the cueball for 1/1000 second, is this true? Then why are we alway advised to follow through?

how long does the tip stay in contact with the cueball? a very small distance, halfway through the stroke or the entire stroke??

how do different speed strokes (soft, medium, fast) affect this?

For three cushion, the cueball is bigger and very heavy. does the contact duration change?

Thanks...

The cue tip is on the cue ball for between 0.8 milliseconds and 2.0 milliseconds, roughly. The time depends mostly on how hard the tip is, how hard you shoot and how far off center you hit.

If you know the speed of the ball you can calculate for yourself the distance that the two travel together before separation. It is roughly 2-3 times as much as the tip is compressed during the shot. If the tip is compressed by a millimeter, the ball and tip travel together while in contact about 3mm.

A softer shot has a slightly longer contact time. For the same cue stick and tip, a heavier ball will have a slightly longer contact time. (A 10% heavier ball will have something like a 5% longer contact time.)

As others have pointed out, the reason to follow through is to have a consistent, straight stroke at a predictable speed. Note that in golf the club head travels less than an inch while in contact with the ball: http://www.youtube.com/watch?v=2Y57pw_iWlk
At golf also, the followthrough is what keeps the action straight.

Here is another amazing fact: When the tip hits the ball, the cue stick slows down to about 50% of the speed it had just before the collision. There is nothing your grip can do to prevent this.

 

[Sloppy Pockets]

The cue tip is on the cue ball for between 0.8 milliseconds and 2.0 milliseconds, roughly. The time depends mostly on how hard the tip is, how hard you shoot and how far off center you hit.


A softer shot has a slightly longer contact time. For the same cue stick and tip, a heavier ball will have a slightly longer contact time. (A 10% heavier ball will have something like a 5% longer contact time.)

Bob, I've been wondering about this for a while. Since contact time is the only chance that frictional forces can act upon the CB, isn't it true that:

1. softer shots
2. softer tips
3. lighter sticks
4. (possibly) narrower tips

...will all increase the amount of spin/action you can put on the ball?

Here is another amazing fact: When the tip hits the ball, the cue stick slows down to about 50% of the speed it had just before the collision. There is nothing your grip can do to prevent this.

Interesting.

I once made some not-very-scientific observations regarding CB velocity and grip strength. I made numerous tries at seeing how many table lengths of travel I could get out of various grips. I was astounded to find that I got the same maximum distance (a little over four table lengths) whether I held the cue with a death grip or if I actually let go of the cue entirely and literally threw it at the CB. This finally convinced me that the cue was doing all the work at impact, and not my right arm anymore.

 

[PGHteacher]

Here is another amazing fact: When the tip hits the ball, the cue stick slows down to about 50% of the speed it had just before the collision. There is nothing your grip can do to prevent this.

You mean I can't "really" "accelerate through the CB"?:crying:

:wink:

 

[Bob Jewett]

You mean I can't "really" "accelerate through the CB"?:crying:

:wink:

Well, you can, and telling a student to do so may get them to not stop before they hit the ball, but it does very little for the cue ball action.

 

[Bob Jewett]

Bob, I've been wondering about this for a while. Since contact time is the only chance that frictional forces can act upon the CB, isn't it true that:

1. softer shots
2. softer tips
3. lighter sticks
4. (possibly) narrower tips

...will all increase the amount of spin/action you can put on the ball?




Interesting.

I once made some not-very-scientific observations regarding CB velocity and grip strength. I made numerous tries at seeing how many table lengths of travel I could get out of various grips. I was astounded to find that I got the same maximum distance (a little over four table lengths) whether I held the cue with a death grip or if I actually let go of the cue entirely and literally threw it at the CB. This finally convinced me that the cue was doing all the work at impact, and not my right arm anymore.

Lots of people who use hard tips get lots of action on the ball. With a harder tip the peak forces are larger, but as long as the tip does not tear apart, the physics says that the amount of spin applied should vary only very slightly.

 

[bbb]

why is it said then that a looser grip allows you to get more spin???

 

[sightline]

Great responses from everyone, especially the instructors:smile:

I watched some slow motion billiard videos on youtube to help me get better picture of what we're talking about...
I didn't realize this until the last few weeks i did some research... Always used to thought that cuetip would remain intact with cueball until the very end of follow through...

I've always try to follow through after every shot thinking the Follow Through part might do what i want the cueball to do.... Now it make sense that follow through helps ensure the execution of a consistent, smooth, predictable speed stroke... well... The good thing was that, at least, I did follow through on my shots for those years..

Now i know better about when to apply force and english...hopefully this will help my game...

Thx Everyone...

 

[Scott Lee]

bbb...Because with a light cradle on the cuestick, you're allowing cue weight, and timing to create the stroke speed...and it's not as much more spin, as it is accurately striking the CB. The more tense you are, the more tiny muscle clenchs redirect the tip slightly. Simply said...it's easier to master.

Scott Lee
http://poolknowledge.com

why is it said then that a looser grip allows you to get more spin???