OB Throw Video for the Physics Nerds

[Colin Colenso]

Thanks for the mention Jsp and Colin. It's so rare when I get something right and somebody notices.

I thought the video was about as clear an exposition of throw as you can get. It takes pretty good shooting to demonstrate the various effects since being a degree off here or there will significantly affect the results. It looks like yours were pretty consistent with the general theory, which testifies to the care in which you set them up. .

I want to also thank you for the snooker videos (should've done it sooner, sorry.) It was great to see snooker at all, much less at this level. I'm wondering what usually ends a 147 break for players of this skill, a flat out miss or having to go for something other than the black because of poor position?

Jim

Thanks Jal,
I think you're pretty spot on with just about everything you've had to say on pool physics that I've seen!

Regarding snooker 147's, early in breaks the player will take the easiest color that is available and so potting the first 8 reds with blacks is pretty rare. It's only around the 8 reds and blacks break stage (64 break) that the player is likely to take risks to try to keep getting position for the black. When a player gets to about 72 points, they have pretty much locked up the frame win, so can try anything.

There are nearly always a few reds which are quite inconvinient for gaining position on the black, and also, the player may risk a tourney high break prize if he takes unnecessary risks to try to keep getting on the black when a pick or blue would make the high break more likely.

When the player does commit to the 147, which is pretty rare, they usually mess up on a pot after not getting a good positional angle. Sometimes they do everything right but just tighten up and make unforced errors towards the end of the break.

The 147 always creates a lot of excitement and a huge roar from the audiences. It is a special feature of snooker. I don't think pool has an equivalent thrill. Maybe running 10 racks woud go close, but it doesn't have that resonance of a Perfect Game as the 147 does.

A 9-dart finish in darts is a comparable sporting achievement that gets a huge audience reaction. But it doesn't build the amount of tension of a 147 which requires 36 shots to build up.

Edit: hehe....I see you just beat me to it Dave The more feedback the better

 

[Gabber]

This follows up on a discussion about OB throw as it is affected by draw a couple of months ago.

This video shows my tests which were done by putting a couple of dimples in the cloth.

I was pretty careful with alignment and have tested these angles quite a lot. The video shows the averages of my testing.

It may shock some of you to know that the OB can vary up to 13 inches on a 1/2 ball shot over 7 feet. That's around 3 full pocket widths, depending on what kind of spin the OB has.

Taking Slow Roll Follow as a medium standard, other spins and speeds vary as follows:
Soft Stun = +3.7 degrees
Hard Follow, Draw and Stun = -1 degree
Inside English = same (-1 if hard)
Outside English = Up to -4.3 degrees for 2 tips.

Enjoy the video here:
http://www.youtube.com/watch?v=D-xtzn4vbiQ

Good video Colin but I dont think the the shots with OE are correct. I just dont see that much throw on that particular shot. There is no way to tell if you are hitting the ball a little thinner than you think you are.

A thought. If squirt is an angle, I dont think it cant be changed by speed. All it means is that the harder you hit a shot with E, the farther it will travel along the squirt line before it begins to swerve and straighten out. Any experiment that relies on a human stroke must be ultimatley flawed.

Gabber

 

[MacGyver]

Certainly it can...

squirt is caused by the tip not getting out of the way fast enough so the ball pushes against it..

At different speeds there are going to be different forces at work between the tip and the ball, causing it to be stiffer or weaker(depending on how the material reacts at certain segments of time) as well as having a different force between the ball and the tip, possibly lowering or magnifying the sideways force on the ball and tip.

If you are right that squirt is a set angle then speed wouldnt affect it, but since it is just a measurement of the reaction between a tip and a cueball, speed is definatly a factor.

 

[Colin Colenso]

Good video Colin but I dont think the the shots with OE are correct. I just dont see that much throw on that particular shot. There is no way to tell if you are hitting the ball a little thinner than you think you are.

A thought. If squirt is an angle, I dont think it cant be changed by speed. All it means is that the harder you hit a shot with E, the farther it will travel along the squirt line before it begins to swerve and straighten out. Any experiment that relies on a human stroke must be ultimatley flawed.

Gabber

Hi Gabber,
I'm actually very confident that the OE shots as shown are accurate.

The CB and OB are only seperated by an inch and I hit along the same line quite precisely on every shot.

For the OE, I have also done the test dozens of times bridging at about 20 inches which is way beyond my cues pivot point, meaning that the contact point would be slightly thicker...but still I get almost identical results.

This is because the squirt over 1" is nearly insignificant as is swerve.

 

[Colin Colenso]

For some of those who saw my recent video which relied on a lot of BHE aiming, I thought I'd bump this thread for their interest.
Colin

 

[JoeyA]

Colin, how much distance is there between the cue ball and the object ball in the video?
Thanks,
JoeyA

This follows up on a discussion about OB throw as it is affected by draw a couple of months ago.

This video shows my tests which were done by putting a couple of dimples in the cloth.

I was pretty careful with alignment and have tested these angles quite a lot. The video shows the averages of my testing.

It may shock some of you to know that the OB can vary up to 13 inches on a 1/2 ball shot over 7 feet. That's around 3 full pocket widths, depending on what kind of spin the OB has.

Taking Slow Roll Follow as a medium standard, other spins and speeds vary as follows:
Soft Stun = +3.7 degrees
Hard Follow, Draw and Stun = -1 degree
Inside English = same (-1 if hard)
Outside English = Up to -4.3 degrees for 2 tips.

Enjoy the video here:
http://www.youtube.com/watch?v=D-xtzn4vbiQ

 

[Colin Colenso]

Colin, how much distance is there between the cue ball and the object ball in the video?
Thanks,
JoeyA

The balls were tapped into dimples and the edges of the balls were one inch apart.

I aimed the CB to a spot on the rail on each shot, being careful to align through the center of the CB. And then pivoting as required for spin with a bridge length close to my pivot point...so ball contact on each shot should me very similar.

 

[JoeyA]

I once played the "Nasty Little Napoleon" some one pocket (when I didnt' know who he was) and the cue ball and the object ball were 1" away from each other and he had an "impossible" cut where he used outside English to cut the ball at an angle that looked like it was impossible to successfully pot the object ball but he was successful. A whoop & wow went up from the stunned crowd and a audible gulp from me as well, as me and my money parted company. The object ball was several feet from the pocket and had lots of distance to take advantage of the OE effect demonstrated in your video.
Thanks,
JoeyA

The balls were tapped into dimples and the edges of the balls were one inch apart.

I aimed the CB to a spot on the rail on each shot, being careful to align through the center of the CB. And then pivoting as required for spin with a bridge length close to my pivot point...so ball contact on each shot should me very similar.