Break Speed vs Hand Speed

Masayoshi said:

I would also guess that 18 oz wouldn't reflect the total weight applied to the object ball because your hand and possible more of your body is also connected to the cue. Not to mention that if your cue is not perfectly aligne to the vertical and horizontal center of the cue ball (which is impossible due to the rails) you will have energy loss due to the cue striking the ball at a different vector than the cue ball will travel and due to energy used in creating english.

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The vertical component of the angle of the stick does mean that some of the energy is transferred to the table.

The reason that most neglect the hand/arm in the equation is because the contact time is very short and relative to everything else, out hands are basically gelatinous blobs that allow the cuestick to basically float during the contact time. Long story short, we simply cannot grip the cue solidly enough to make much of a difference in the impact mass of the cue.

Bob Jewett said:

A.D. Moore, who wrote a paper about Willie Hoppe's stroke, measured the actual speed ratio in 1940 or so by suspending stick and ball on strings (like a swing) and then measuring how high the ball swung up compared to how high the cue stick started. He got 130% of the stick speed compared to the 150% you would expect for a perfect collision.

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Interesting. For anyone doubting the physics behind all this, that's pretty much exactly what you'd predict using the formula and a tip with a COR of 0.87 (150% x 0.87 = 130.5%), which is what Dr. Dave said Coriolis used in his book (I don't have the Coriolis book). It appears that real-life experiments yield the same results as the predicted values.

Who'd a thunk?

Sloppy Pockets said:

Thanks, but it's really Dr. Dave (and others) that worked all this out for us over the years. I'm just a student of the game.

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I didn't mean you were the first to correctly apply physics to this question; I just meant you had it right.

If we're deferring credit to the innovators in this field, we'll have to go back at least as far as Newton.

-Andrew

CSykes24 said:

uhhhhhhhhhh wat

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Apparently it wasn't as dumb as it sounded.

FWIW I am re-posting those graphs I posted in the other thread because there seems to be a lot more activity/interest going on in this thread.

The graph on the left shows what happens to the CB speed as progressively heavier cues are swung at the same speed. The vertical axis represents the factor by which a 6oz CB's speed changes as the cue weight varies, the horizontal axis represents the cue weight in ounces.

Notice that for a 6oz cue striking a 6 oz CB (green line on left), the factor on the vertical axis = 1. This means that there is no increase or decrease in CB speed. This is equivalent to the transfer of momentum involved in a perfect stop shot using two balls of equal mass, where the OB leaves at the same speed as the CB that hits it, the CB stops dead in its tracks, and momentum is completely conserved.

The green line in the middle is for a "standard" cue of 18oz, or 3X the mass of the CB. Neglecting any energy losses involved in this collision, the CB departs at 1.5X the cue speed (which continues in a straight line after contact at half its original speed). Again, momentum is conserved (MV 1 = MV 2).

The green line on the right represents a 24oz cue, which will impart a slightly faster speed to the CB at the same cue speed (1.6X faster).

The second graph shows what would happen as you continue to increase the mass of the cue while swinging it at the same speed. You can see that as the cue approaches infinite weight, the CB will never move faster than 2X the cue speed after impact. IOW even a Mac truck hitting a CB at 5 MPH will never send the CB away faster than 10 MPH.

So the real question is can one swing a 15oz cue FASTER (@ CB contact) than say a 20+ oz cue enough to over come the difference in the amplitude multiplier related to the mass/energy exchange of a heavier cue stick. This would require an individual study of the 'fast twitch striated muscle fibers' involved in a the break shot for 'that individual' for a real answer for that individual. Everybody is made different.

think Pan Xiao Ting. 9-ball.

https://www.youtube.com/watch?v=DjSGwYrZLzA

Andrew Manning said:

But the cue would keep moving forward after contact with the CB, even if you weren't touching it. If you completely let go of it the instant before impact, it would still follow the CB down the table after impact.

High school physics (conservation of momentum and conservation of kinetic energy) tells us that when a heavy moving object strikes a lighter stationary object, the light object moves forward faster than the heavier object was originally moving, but the heavier object also continues moving forward.

Or in other words, take Sloppy Pockets' word for it, because he clearly knows his basic physics.

-Andrew

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Yes it would follow even without more force behind it, but because there IS more force behind it though you arm, it should not be used as an example of the effect without some detail, which is why I said you need to set up the cue in a pendulum and swing it down at the ball in a natural ark without the external energy of your arm changing things. You can't just say there you can see there is more force in the cue after it hits because the cue moves forward because in a regular break shot your arm is still pushing forward on the cue after it strikes the cueball.

It would be like trying to measure the average speed of a fish but only measuring it when there is a shark chasing it.

Bob Jewett said:

High-speed videos have shown that that hand-cue coupling/attachment is so soft that the hand and arm can be ignored during the tip-ball contact. This is very, very hard for many to believe, and we'll probably see some contrary comments here, but such disbelievers should look at the videos. Seeing is believing. More importantly, seeing allows you to measure various things like the tip-ball contact time and (indirectly) the hand-stick Hooke's constant.

For some discussion and measurement, see http://www.sfbilliards.com/articles/1999.pdf -- page 10 in the PDF.

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I think it's been hard to accept such things for many of us because it just feels so much like your hand and arm are adding to the force felt by the CB. Just recently I've been playing a ton with a jab stroke. It's hard to believe you can generate so much power over such a small distance with just the weight of the cue. The hit feels crisper, the ball seems snappier, the balls react differently, they even sound different to me. The whole game just seems as compact as the stroke.

And yet, I have seen the videos and I have to accept that this is just perceptual, and not based upon some sort of voodoo pool physics.

Absolutely correct, and for those of us not blessed with an abundance of these types of muscle fibers we would have to develop them.

Of course the timing and technique in breaking the balls hard helps too.

rhatten said:

So the real question is can one swing a 15oz cue FASTER (@ CB contact) than say a 20+ oz cue enough to over come the difference in the amplitude multiplier related to the mass/energy exchange of a heavier cue stick. This would require an individual study of the 'fast twitch striated muscle fibers' involved in a the break shot for 'that individual' for a real answer for that individual. Everybody is made different.

think Pan Xiao Ting. 9-ball.

https://www.youtube.com/watch?v=DjSGwYrZLzA

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BarTableMan said:

OK pool scientists, help me understand this: a pitcher moves his hand at 90mph so the baseball moves at near 90, but how fast does the break hand/cue move compared to the speed of the cue ball to the rack? There must be a ton of loss. 50-70% loss in speed transfer? Example: is the hand moving at 50mph and the cue ball 20 mph? Thoughts...

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The Pitcher isnt hitting the baseball with his hand, he is throwing it, so his hand is moving near 90mph... As far as a break shot a 20mph break shot the cue stick is moving aprox 13-14 mph....

Tony_in_MD said:

Absolutely correct, and for those of us not blessed with an abundance of these types of muscle fibers we would have to develop them.

Of course the timing and technique in breaking the balls hard helps too.

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Tony, what is you opinion about strength training for pool players to increase the percentage of fast twitch muscle? I notice that a lot of top players are looking pretty buff these days. I'd worry that it might make some players less able to have fine cue control even if it did possibly improve their break speed.

Do you know of specific exercises that would accomplish this goal? When I studied martial arts as a young man, my sifu was big into weight training. He didn't push heavy weights as much as he did doing the reps as explosively as possible. This was the key to developing both striking power and speed in his opinion, rather than just brute strength developed by using increasingly heavier weights.

I have posted on this before in the Instructors section. I am a believer in weight training for everyone. When I was a young man I competed in weight lifting events and spent more time in a gym than I would like to admit.

To develop fast twitch muscle fibers, heavy weights and low reps 3-5 should be used. The lower weights and long reps 8-12 build endurance which slow twitch muscle fibers are used for. You want the reps to be explosive and quick. you will need to work those muscle groups involved in the break, biceps, shoulders, your core, hips and legs.

A good all around exercise that hits just about every muscle are power cleans. https://www.youtube.com/watch?v=ePdfXwyjyHw

Doing these and a few other exercises, curls, lat pulldowns, crunches leg-extensions and leg curls, (stay away from back and front squats for now) would be enough to start. Remember you are training to improve your pool game, not to compete in Mr Olympia.

I don't believe that weight training promotes a loss of touch. You need to spend the time at the table to further keep that aspect of your game as you get stronger.

Sloppy Pockets said:

Tony, what is you opinion about strength training for pool players to increase the percentage of fast twitch muscle? I notice that a lot of top players are looking pretty buff these days. I'd worry that it might make some players less able to have fine cue control even if it did possibly improve their break speed.

Do you know of specific exercises that would accomplish this goal? When I studied martial arts as a young man, my sifu was big into weight training. He didn't push heavy weights as much as he did doing the reps as explosively as possible. This was the key to developing both striking power and speed in his opinion, rather than just brute strength developed by using increasingly heavier weights.

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Bob Jewett said:

High-speed videos have shown that that hand-cue coupling/attachment is so soft that the hand and arm can be ignored during the tip-ball contact. This is very, very hard for many to believe, and we'll probably see some contrary comments here, but such disbelievers should look at the videos. Seeing is believing. More importantly, seeing allows you to measure various things like the tip-ball contact time and (indirectly) the hand-stick Hooke's constant.

For some discussion and measurement, see http://www.sfbilliards.com/articles/1999.pdf -- page 10 in the PDF.

Click to expand...

Thanks for posting these excellent articles.