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Sorry. Just making myself something to eat. I'll have a look at those links now MF.
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cheers. just the first one ...
the index link has got toooooooooo much stuff for tonight at least lol. |
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Yep, good links those MF.
I have actually corresponded with the chap responsible for that site when I worked as a billiard columnist for an American magazine. Clever man, his name is David Alciatore. What those videos clearly show, however, is that no overspin (topspin) is present in the cueball as it approaches the object ball. And, after collision, where the cueball spins on the spot, what we are witnessing is a form of backspin as the ball's momentum tries to force the ball in the direction it was travelling before it was stopped dead. The key point to note is that this action happens when the ball is just rolling naturally. In its approach there is clearly no overspin actioned on that cueball. The same thing would happen if it was originall struck middle ball from a few feet away. Thank you very much for the link sir. |
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Im agreeing.. But with the marked ball and table.. isnt that showing an intial top spin.
So putting topspin on a cueball is possible.. but simplistically, just not enough topspin to 'do' anything. Must try sleep now.. gn |
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Coincidentally, going back to my discussion with Burt earlier, had you promoted much of what David has proven on that website a few years ago, you would have probably found yourself being burned at the stake as a witch.
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Just back from the boozer and a little tiddly. Was thinking about this and had a quick glance at thread when I got home. I now buy into the backspin rather than topspin theory. Reverse backspin if you will.
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You're referring to the split second that the tip overcomes the static friction of the ball on the cloth?
Hmmm! Does it show the tiniest fraction of overspin before the ball starts rolling? I'm not so sure at all. I think David was trying his damnedest to show this very reaction, MF, and probably picked the one clip of many that might possibly be interpreted as such because it was quite a hot topic in the billiard world when that film was posted. For me, that clip shows no overspin. And if it appears to do so for one 100th of a second before the ball begins to roll, I would easily attribute that to skipping over the tiniest of blemishes on the felt. The other players he mentions on his site, Bob Jewitt and Robert Byrne agree with me, by the way, and they are both highly respected in their fields of expertise. |
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Anybody who enjoys cards should enjoy watching Ricky Jay, an absolute master of card control.
Stick his name in the youtube search box, you may be there for over an hour on different vidoes, but you will be amazed. |
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Good morning Easter. :)
I am glad to welcome you in from the Dark Side, sir. |
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Yep, he is amazing Charlie. The one where he continually deals out four aces from the pack, all the while shuffling them, is indeed an art in itself.
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Time to officially close this discussion, gentlemen. I'm off to bed and probably will not be back online for some days.
Many thanks for all contributions to the debate this evening. Goodnight. |
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http://www.engr.colostate.edu/~dga/pool/technical_proofs/new/TP_A-30.pdf
Interesting P.. ^ ? gn for real.. :) |
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^^^^
Nice find! 4-2 contains the important calculation: that the centre of percussion (i.e. the point of horizontal cueing which will cause the ball initially to roll without slipping or sliding) is 2/5 of the ball's radius vertically above it's centre. Cueing above this point will cause the ball to slip initially (topspin), cueing below will cause it to slide initially (screw). |
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just copied this entire thread and sent it to my work email. will read it later and give you all the correct answer when i return this evening.
:) |
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i think pokermonster must be wrong here but i will try out the blue ball thing at the golf club today and report back tonight.
and sorry for the fishing comment last night mate, i hadn't bothered to look through it properly. I have now read all through the post again and it is a great thread. |
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I don't suppose Pokermon would put something up like this unless he was absolutely sure. Reckon you could do a phD in the physics of a snooker ball.
I think he is right though, how could you possibly make something spin in the direction it is moving. You would need a lot of friction between cloth and underside of ball I suspect, in fact I suspect it is impossible to do for a sphere on a flat surface regardless of the materials. To spin backwards, the surface of the ball touching the cloth has to be moving backwards across the cloth while the overall movement of the ball is forward. It can be done if you were to pick it up with you hand and spin it backwards then dropping it with a forward motion onto the table I think. But think of the amount of backward force you would be putting on the underside of the ball to achieve this (in tandem with a forward thrust on the top of the ball). No way you could replicate this with a cue for forward thrust on the top of the ball, and just friction working against the bottom of the ball. Can't be done. Except if you pick it up and give it a tweak. Pretty sure this is outlawed in the modern game, perhaps poker or someone could clarify on this matter. |
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pokermonster is correct
The truth is incontrovertible, malice may attack it, ignorance may deride it, but in the end; there it is." -- Sir Winston Churchill |
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... how could you possibly make something spin in the direction it is moving...
What about spinning the driving wheels of a car by giving it too much gas when pulling away? |
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I may be convinced of the PM argument here. The sandpaper vid conclusion is fairly clear cut.
Might be similar to : A pushbike held upright with cranks vertical. a rope tied to the bottom pedal is pulled backwards, does the bike go forward or backwards. (goes backwards) |
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The best you can do is make sure the cue ball is spinning fast enough to ensure it is not slipping on the cloth, then after impact the rotational momentum will keep it moving forward. If you hit a ball hard it has to be hit with top to make sure it is spinning fast enough but it will not be spinning faster than it is rolling. WP Pokermonster.
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Question..a top-class snooker player strikes a cue ball sweetly at the top 10 times, and 10 times the ball spins (not rolls) forward after contact with an object ball
He strikes it with equal force and skill at the bottom of the cue ball 10 times, and 10 times the ball spins (not rebounds) backwards after contact. I hope we're in agreement that would happen? Apologies if that has been covered somewhere, but why would that be? |
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The ball always has the same linear momentum not much quibble.
I also has rotational momentum. No evidence on topspin argument so far that rotational momentum can be imparted greater than that associated with no slip forward rolling. Negative rotational momentum is evident if struck below centre. |
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I may be convinced of the PM argument here. The sandpaper vid conclusion is fairly clear cut.
That was pretty smooth sandpaper, why didn't they use a heavier grade? |
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What was it 600 grade polishing paper?
I can assure you that is pretty smooth. |
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Right I have just got back from the golf club and, wait for it, I am totally astonished to report pokermonster is right and I am wrong. :(
I tried out that blue ball test thing. It took me a few goes to get the blue to land in the same place but when it did the white ball stopped in exactly the same place no matter how much topspin I put on it!! I tried several more times to make sure and it works every time - if you hit it at the same pace the white travels the same distance whether you hit it middle ball or with loads of topspin. Unbelievable to me, but there you go. Give that man a medal. |
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The friction of the surface has nothing to do with initial motion of the ball, i.e. whether it rolls, slips, or slides. It does, however, determine how rapidly the rolling condition will be achieved after striking.
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how does that effect pan out in the test i did today?
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Friction. Determines everything
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what does that mean?
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Thanks for posting gentlemen. :)
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munch man 20 Jan 17:12
Right I have just got back from the golf club and, wait for it, I am totally astonished to report pokermonster is right and I am wrong. :( I tried out that blue ball test thing. It took me a few goes to get the blue to land in the same place but when it did the white ball stopped in exactly the same place no matter how much topspin I put on it!! I tried several more times to make sure and it works every time - if you hit it at the same pace the white travels the same distance whether you hit it middle ball or with loads of topspin. Unbelievable to me, but there you go. Give that man a medal. please post instructions again, i , lazily, cant be bothered to trawl through this thread again. i wanna try this. Nice post. |
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There is a simple test that proves this point:
Start with the cueball on the brown spot and the blue on its own spot. These are the only two balls on the table. First shot: Send the white into the blue at an (almost) full on collision, sending the colour up over the pink and black spots and back to baulk, coming to rest within two inches the baulk cushion. If the blue bounces back into the white, start again. This first shot should be played plain ball. Note where the white finishes. Second shot: Replace the balls and try again using as much topspin as you can muster. You can even move it closer to the blue if you like. Keep trying until the blue finishes in the same place as before; this is your proof that you have not inadvertantly struck the white harder. Note where the white finishes. It will be in the same place as with the first plainly struck shot. Good luck, sir. |
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ty, i will report back as soon as required. it may be some time, but i don't care and i am sure you don't.
bedtime for me now gn. |
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Goodnight.
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To be continued in Feb edition of "Angling Times",lol.
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An interesting read I stumbled upon.
Thanks PokerMonstor |
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Pokermonster even....
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If you could have a quick read through the thread, Ned, you will see that I was in no way fishing, sir.
Furthermore, many posters, perhaps even the majority, agreed with me towards the end. |
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You're very welcome Pjay; glad you found it of interest, sir. :)
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A pleasing thread. Well done, Pokermonster. Vey well done, indeed!
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