Please Describe 'Acceleration thru the CB"
- Thread starter LastTwo
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Egg McDogit said:
Arguments come down to semantics, because words have meaning. And using the wrong wording causes the readers to come away with the wrong meaning. Once of the purposes of the AZ discussion group is to convey valuable meaning to others. Let's do it the best way possible.
When you say "convey the idea," just exactly what idea are you talking about? Seriously, I have zero idea what you mean.
Jeff Livingston
I meant exactly that. It's a good practical way of conveying the concept of a good stroke. It promotes good stroking/following through - and prevents bad stroke habits, such as flinching/slowing down your stroke before impact. In otherwords, keep the concept in mind, try to practice it and make it second nature, don't worry about the nitty gritty details - whether you're actually accelerating through or impacting at a constant velocity, etc. By just attempting to accelerate through the cueball, you should be stroking it pretty good and burning in good stroke habits.
I get pretty good cueball action and I don't stay up at night wondering about details like whether I'm truly accelerating up to/through the cueball. Some people do though
And while their discussion honestly won't lead to me changing my stroke to try to get even more juice, I do find it interesting.
peace
-egg
I get pretty good cueball action and I don't stay up at night wondering about details like whether I'm truly accelerating up to/through the cueball. Some people do though
And while their discussion honestly won't lead to me changing my stroke to try to get even more juice, I do find it interesting.peace
-egg
chefjeff said:
Egg McDogit said:I meant exactly that. It's a good practical way of conveying the concept of a good stroke. It promotes good stroking/following through - and prevents bad stroke habits, such as flinching/slowing down your stroke before impact. In otherwords, keep the concept in mind, try to practice it and make it second nature, don't worry about the nitty gritty details - whether you're actually accelerating through or impacting at a constant velocity, etc. By just attempting to accelerate through the cueball, you should be stroking it pretty good and burning in good stroke habits.
I get pretty good cueball action and I don't stay up at night wondering about details like whether I'm truly accelerating up to/through the cueball. Some people do though
peace
-egg
"More juice?"---what's that? You mean "exactly" what? "In otherwords?" Why use "otherwords?" "Second nature?" What is the first nature? How it "attempting" to accelerate not really accelerating? Or is it really accelerating as you've said it is? So a "good stroke habit" is developed by doing something other than what you say you're doing?
Confused even more than before,
Jeff Livingston
*more juice = less than too much but more than before
*exactly = not exactly more or less but just about exactly inbetween
*otherwords - not those words, but the other ones
*second nature - the one after first
*first nature - the one before second
Hopefully the above and some meditation elucidates the rest for you.
peace
-egg
*exactly = not exactly more or less but just about exactly inbetween
*otherwords - not those words, but the other ones
*second nature - the one after first
*first nature - the one before second
Hopefully the above and some meditation elucidates the rest for you.
peace
-egg
chefjeff said:
Skeezicks said:
The tip is on the ball for about one millisecond on a center-ball hit and
about two milliseconds when extreme spin is used, according to the results
obtained by Bob Jewett and others of the Jacksonville Project (high speed
photography). This time varies according to how hard or soft the tip is:
the harder the tip, the less time it stays in contact with the cueball.
The only way you can lengthen the contact period is by hitting a softer
shot, which I think defeats the purpose of why you would want to
lengthen the contact time in the first place! In other words, the contact
period actually decreases as you hit harder (higher cue speed) or apply
force during the impact.
People mistake the extra action they get on the cueball when they extend
their strokes as due to increased contact time, when in fact just the
opposite occurs. What really happens is that their cue speed has increased,
for reasons discussed earlier in this thread.
It's a pretty natural way to think of it though. I can almost feel the tip
grabbing and holding on to the cueball when I extend my follow through.
Jim
chefjeff said:
I think what Egg McDogit is saying is that you can't accelerate the cue
during the contact period, which is true, and therefore we shouldn't take
the phrase "accelerating through the cueball" too seriously. Fair enough,
but you can (and will) accelerate the cue before and after impact if you're
still applying force to it in the positive direction. So, in this sense, you are
"accelerating through the cueball".
In fact, the cue accelerates in the positive direction after impact even if
you're not applying force, as high speed photographs (Jacksonville Project)
have shown. It happens as the cue, which was slowed down to about half
its speed by the collision, catches up with the hand which is now moving
faster than it.
Jim
Jal said:
It's only different in how far the stick moves before it reaches its peak. I think the shape of the velocity vs. time curve is substantially the same, unless you are making some very strange changes in the acceleration curve.
my bad I thought you were being sarcastic in your last post lol
peace
-egg
peace
-egg
chefjeff said:
Bob Jewett said:
It is, more or less, but it is a different curve and I'd guess you'd have to
plot out a family of curves to see that as you increase the stroke length,
the cue's speed increases but becomes ever more insensitive to changes
in the length of the stroke.
If you differentiate the velocity relation with respect to "w", the angular
frequency, you get a maxima corresponding to an impact occuring at
wt=113.14 degrees. This is a true maxima (not a minima or inflection
point) and a speed increase of 20% over an impact occuring at wt=pi,
the nominal case.
Like any maxima, it also is the point at which the cue's sensitivity
to changes in w is zero, by definition. You'd have to increase your stroke
length to three times its nominal length to get there, so it's impractical,
but any increase has the advantages mentioned, I believe.
These things are true (I'm asserting) if the force as a function of time
is a pure sine wave. Distortion with harmonics changes the numbers a
bit, but not too much, depending of course on the magnitude of the
harmonic content.
I'm not pushing accelerating through the cueball, but it does seem to
have its place as a specialty shot.
Jim
No, it's a lot more like hitting a stack of hay bales. There is no reason to accelerate after or even during the impact. If you needed to hit the hay bales at exactly 30MPH, how would you go about it? I'd accelerate up to 30 and more or less coast into the bales.RichardCranium said:
RichardCranium said:
Picture the force you're applying to the cue from the start of your stroke
to the moment of impact. Whenever you're applying a force, by the way,
the cue's speed is changing, increasing or decreasing (accelerating
positively or negatively), which I'm sure you understand.
What typically happens is the force starts off at zero and increases gradually
to some maximum roughly half way through the stroke. Then it begins
subsiding and reaches zero around the moment of impact. Even though the
force is diminishing during this period, the cue's speed is still increasing
because the force is still in the forward positive direction and nonzero.
Shortly after impact the force turns negative (i.e, you begin pulling instead
of pushing the cue) and the cue eventually comes to a stop.
I'm not sure this follows your analogy too closely but I hope it's clear so
far.
I'm saying there are some benefits to hitting the cueball while the cue
is still accelerating positively (its speed is still increasing). They are:
increased cue speed when you need it, and decreased sensitivity to
some errors that can occur during the stroke. This has absolutely nothing
to do with the fact that the cue is actually accelerating during impact, but
with what you have to do during the stroke to get it to do so. It's a
consequence of the shape of the force vs time curve from the very start
of the stroke up until the time of impact.
To achieve this you have to lengthen your stroke, either by changing your
muscle timing or by gripping the cue further back.
Obviously, Bob Jewett doesn't agree with this, which gives me some pause
because he knows a lot, but I've spent so much time working on this I'll be
amazed if it's not true.
To address what I think you were getting at, one of the errors that tends
to diminish is the sensitivity of the cue's speed to changes in the length
of the stroke due to variations in muscle timing. This is pretty surprising
since you would think that some error, say 10%, in stroke length should
be ever larger as stroke length increases. While this is true, the effect
on cue speed still manages to diminish. It is not at all obvious that this
should occur, but according to my calculations, it does. And the reason
is that the shape of the force vs time curve is generally flatter (less steep)
for a longer stroke.
Hope this helps. If you understand it, please explain it to me again after
Jewett gets done working me over.
Jim
bruin70 said:
I mean the actual stroke length, keeping everything else the same:
bridge length, how far you draw the tip back, the peak force you
apply to the cue, etc.
One major disadvantage to accelerating through the cueball is that
errors in cue speed due to variatiations in bridge length increase.
Please see the other message I just posted for more details if you're
interested.
Jim
i don't know what you used to gauge your observations, but i must say that i can't see what you say........
"What typically happens is the force starts off at zero and increases gradually to some maximum roughly half way through the stroke."
i don't see this happening. i feel an increase in speed, starting at zero, and reaching maximum JUST passed half way, and THAT is moment of impact.
i do not understand your "Then it begins subsiding and reaches zero around the moment of impact.",,,, because i don't see impact at the point when the cue decelerates to zero. how can one propel a cb when speed has reached zero,,,unless by zero you mean a point at which the cue is neither accelerating nor decelaerating? that either makes no sense, or i am misinterpreting you.
"Shortly after impact the force turns negative (i.e, you begin pulling instead of pushing the cue) and the cue eventually comes to a stop."
i don't see this either. i think a good player strokes evenly through the cb. if there is deceleration, it is only near the end of the stroke, not after impact. the only players i see "pull back" are bad players who poke at the cb.
there is an iteration of the obvious in this whole acceleration theory, because acceleration/deceleration is part of the natural movement of things. so i think to try and break this down in a stroke that occurs in a span of 6-8 inches is almost pointless.
and if acc/dec is the natural flow of movement, then what is left is the timing...at what point does the cue contact the cb. this is true in all sports,,,that sweet point when the club or bat or cue impact the ball perfectly. in pool, both changing the length of your bridge and/or changing where you grip the cue will affect the timing of the hit.
i think it is a VERY bad thing to be conscious of the acceleration/deceleration of one's stroke...mainly,,,,,it can't be helped. i don't think one can consciously accelerate his stroke without totally screwing up his rhythm.
"What typically happens is the force starts off at zero and increases gradually to some maximum roughly half way through the stroke."
i don't see this happening. i feel an increase in speed, starting at zero, and reaching maximum JUST passed half way, and THAT is moment of impact.
i do not understand your "Then it begins subsiding and reaches zero around the moment of impact.",,,, because i don't see impact at the point when the cue decelerates to zero. how can one propel a cb when speed has reached zero,,,unless by zero you mean a point at which the cue is neither accelerating nor decelaerating? that either makes no sense, or i am misinterpreting you.
"Shortly after impact the force turns negative (i.e, you begin pulling instead of pushing the cue) and the cue eventually comes to a stop."
i don't see this either. i think a good player strokes evenly through the cb. if there is deceleration, it is only near the end of the stroke, not after impact. the only players i see "pull back" are bad players who poke at the cb.
there is an iteration of the obvious in this whole acceleration theory, because acceleration/deceleration is part of the natural movement of things. so i think to try and break this down in a stroke that occurs in a span of 6-8 inches is almost pointless.
and if acc/dec is the natural flow of movement, then what is left is the timing...at what point does the cue contact the cb. this is true in all sports,,,that sweet point when the club or bat or cue impact the ball perfectly. in pool, both changing the length of your bridge and/or changing where you grip the cue will affect the timing of the hit.
i think it is a VERY bad thing to be conscious of the acceleration/deceleration of one's stroke...mainly,,,,,it can't be helped. i don't think one can consciously accelerate his stroke without totally screwing up his rhythm.
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bruin70 said:
I see the same. Actually at impact the stroke slows down not because you are pulling back, your not, your still going forward. Hitting the cue ball is a bit of friction that causes some slowdown and then afterwards you begin to reach the end of your stroke, much like a swing that loses energy and begins to fall backwards.