I guess I should say that I meant unintentionally. I mean a single clean stoke as if to move the cueball two or four feet, depending on conditions. I'm really asking about the feeling, or noise, of the shot. Like a slight ferrule or joint imperfection, but only some times.sjm said:Not sure what physics has to do with it, but the answer is yes, you can double hit the cue ball even when there is no object ball near the cue ball. Obviously, the danger of doing so is far less in this situation.
longhair said:I guess I should say that I meant unintentionally. I mean a single clean stoke as if to move the cueball two or four feet, depending on conditions. I'm really asking about the feeling, or noise, of the shot. Like a slight ferrule or joint imperfection, but only some times.
Yeah, I know. But I really don't think that's what it is. I'm not doing a very good job of asking a question. Have you ever felt a slight vibration, on a very soft follow shot, with a cue that is otherwise completely solid?Rodd said:Maybe that's what you have, a loose ferrule , tip not completely glued on (common), loose weight screw or butt rubber plug.
Rod
longhair said:Hey Bob Jewett and all the other physics types:
If you hit very very softly, especially with a follow stroke, sometimes you might hear or feel a funny vibration. Is it possible that this is actually a multiple contact?
longhair said:Yeah, I know. But I really don't think that's what it is. I'm not doing a very good job of asking a question. Have you ever felt a slight vibration, on a very soft follow shot, with a cue that is otherwise completely solid?
longhair said:Thank you for your replies.
It sounds like other have felt this and understood it the way I did.
DaveK,
how did you stop making double hits in your exercise? Did it just take a smoother stoke?
cheffjeff,
I don't suppose you know where I can find that article online? As I type this I realize I haven't even checked the BD website yet. lazy.
mjantti said:This has been covered in a few books:
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If you have the cueball near the object ball and you're cutting it maybe half ball or thinner(cue direction is the red arrow) using heavy outside english, you might hit the cueball twice quite easily. The problem of perceiving this foul is the fact that there isn't much difference between the double hit speed and the legal hit speed. Only thing that changes is the path of the cueball, legal shot will have the cueball travelling along the tangent line (green arrow)and the foul shot will have the cueball travelling more towards the first cushion (blue arrow).
Any opinions on this shot ? Grady ?
Nope. Most shots are single hits. Hal Mix related a third-hand story of an ultra-high-speed video that was made (on real film) a long time ago, but the details of the experiment are not known. My suspicion is that for that film, the shaft was directed at the ball by an air gun or a small cannon. See "Dr. Dave" Alciatore's high-speed videos for more recent results.chefjeff said:Bob Byrne (or was it Jewett?) did an article in BD a few years ago and talked about an experiment a college student did that, using high-speed photography, showed without a doubt that the cuetip hits the cueball at least 5 to 6 times on every shot....
longhair said:DaveK,
how did you stop making double hits in your exercise? Did it just take a smoother stoke?
Bob Jewett said:Nope. Most shots are single hits. Hal Mix related a third-hand story of an ultra-high-speed video that was made (on real film) a long time ago, but the details of the experiment are not known. My suspicion is that for that film, the shaft was directed at the ball by an air gun or a small cannon. See "Dr. Dave" Alciatore's high-speed videos for more recent results.
For an amazing on-line demo clip that shows a tip hitting a ball, see Windows Media Video filechefjeff said:Thanks for the clarification, Bob....my memory must be playing tricks on me.
Jeff Livingston
Bob Jewett said:For an amazing on-line demo clip that shows a tip hitting a ball, see Windows Media Video file
http://www.bskunion.at/efler/Faszination_Dreiband_Windows_Media_9.wmv
Note that if your browser doesn't know what to do with a WMV file, you probably will not see anything useful.
There is only one contact. On the Jacksonville Project video, there was some indication that there were multiple hits on side spin shots, but I think that was due to the way Iron Willie held the stick.
The video that the clip is from was shot and produced by a group in Austria. I think the player was Andreas Efler. The part of the cue ball that rubs on the cloth is heated and the cloth is heated in masse shots. (The false-light videos are infrared (heat) not ultraviolet (black) light.)mjantti said:Very cool video ! It seemed the temperature of the cueball increases slightly on a heavy masse shot ? Also, on a hard shot (I presume), part of the chalk disappears before the tip hits the cueball... at least one shot closeup showed a chalk cloud around the tip before the impact. Wow.