more squirt for harder shots? -Miz cue from Hell

[Jal]

If it helps, a softer tip will cause increase contact time translating to more grab resulting in more spin. Harder tip requires a much softer stroke to acheive the same. (Harder tips will tend to skid more off the CB)

Thank you Pete. There was something about the way you put it that helped me to come up with an intuitive argument for this. But Mike Page's explanation is much more convincing than mine, so I won't go into it.

Jim

 

[Jal]

One way to see it is to imagine the hard tip is extremely hard and that its contact time is extremely short. Hit a ball with with this tip at an offset of, say, 10 mm. The contact time is so short that the force both during compression and during decompression is acting at 10 mm. You will get a cueball with a spin/speed ratio characteristic of a 10mm offset.

Now hit the same shot with a normal tip with a 1 ms contact time. After compression of the tip the cueball has attained about half its forward speed and about half its spin. It's also moved forward some and rotated some so that the compressed tip has an offset of 10.5 mm instead of 10mm. Then the rest of the acceleration of the ball, during decompression, is occuring at offsets between, say 10.5 and 11.0 mm. I think this cueball, struck at 10 mm will have a spin/speed ratio characteristic of perhaps a 10.5 mm offset. Go now to a somewhat softer tip and the effective offset might increase to 10.6 mm.

If you ignore this effect, then I agree a soft tip and a hard tip give the same result: it's the impulse--the area under the force versus time curve--that matters.

mike page
fargo

Thanks again Mike. You've pulverized whatever mental block was preventing me from seeing this. I even considered the near rigid body collision, but it didn't help.

Jim

 

[Jal]

I wonder if part of the reason many players are convinced that harder shots lead to greater squirt is the effect harder shots have on throw. That is, at high speed, throw is significantly reduced.

Excellent point. I think many players don't appreciate this or just how much the throw is reduced. It gives me fits all the time.

I don't know if you're familiar with this article on throw. It's one of the best on the subject. If you don't want to wade through the math, the graphs are very informative, although non-technical people might scratch the heads over the axis labels.

http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-14.pdf

Jim

 

[pete lafond]

This, imo, has been as well known and as well established as the idea in 2003 that Iraq had an advanced clandestine WMD program.

mike page
fargo

Didn't need that. What I should have said is "Is has been believed that the harder the shot the more squirt."

Also, on SJM's 14.1 break shot I will normally shoot this shot by slightly jacking up my back hand, making absolutley sure I am using parallel english and driving the CB into to felt. (no, my back hand is not raised in the air rather it is up a mere 1" than normal)

My interest is to hook the CB with a hard and fast dive off the rail so that it hits low on the pack hitting the corner ball. A little more swerve than a normal hard shot because I am hitting it high and down occurs even though I pay more attention to the squirt because I'm hitting it hard. I have to do this way because otherwise I will miss the shot excution desired. Also what changes for me on this shot is also how the felt has been reacting.

 

[Colin Colenso]

Excellent point. I think many players don't appreciate this or just how much the throw is reduced. It gives me fits all the time.

I don't know if you're familiar with this article on throw. It's one of the best on the subject. If you don't want to wade through the math, the graphs are very informative, although non-technical people might scratch the heads over the axis labels.

http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-14.pdf

Jim

Yes, I'd seen the graph before and was intrigued by the significant reduction of throw at higher velocities.

As it can account for around 2-3 degrees of difference from dribble in to power shot speeds, on wider angles, it deserves attention and adjustment for.

 

[pete lafond]

Yes, I'd seen the graph before and was intrigued by the significant reduction of throw at higher velocities.

As it can account for around 2-3 degrees of difference from dribble in to power shot speeds, on wider angles, it deserves attention and adjustment for.

Here is an easy way to prove this. Have two balls touching as shown in the wei table. Hit one hard and then set it up again and hit the next one soft. The one you hit hard will hardly throw and you will miss, the one you hit soft will pocket. This will translate to a single ball as well which proves the above, putting two balls together lets you see it better. (yes even though there are two balls here, both balls are thrown together even though the first travels on a different path)

START(
%Aj9J6%BL7P8%CJ5O4%DL7N1%El1J0%FK6P1%GK6N8%HM7N8%IL7O4%JK6M5
%KJ5P7%LJ5N2%MK6Q4%NJ5R0%OJ5M0%Ph1V2%Wj3L6%Xh4U2%Yr5D3%Zl9I5
%[s3E9%\l9I5
)END

 

[Colin Colenso]

Here is an easy way to prove this. Have two balls touching as shown in the wei table. Hit one hard and then set it up again and hit the next one soft. The one you hit hard will hardly throw and you will miss, the one you hit soft will pocket. This will translate to a single ball as well which proves the above, putting two balls together lets you see it better. (yes even though there are two balls here, both balls are thrown together even though the first travels on a different path)

START(
%Aj9J6%BL7P8%CJ5O4%DL7N1%El1J0%FK6P1%GK6N8%HM7N8%IL7O4%JK6M5
%KJ5P7%LJ5N2%MK6Q4%NJ5R0%OJ5M0%Ph1V2%Wj3L6%Xh4U2%Yr5D3%Zl9I5
%[s3E9%\l9I5
)END

Yes Pete,
That is a very good way to prove this effect to people / students!

 

[mikepage]

Didn't need that. What I should have said is [...]

Sorry, I was being flip.

mike page
fargo