New videos from Dr. Dave and Bob Jewett

dr_dave

dr_dave

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FYI, Bob Jewett and I filmed a bunch on stuff together a couple of weeks ago, and I finally got everything edited and posted. The first stuff we shot dealt with some pool physics topics:


Most people will probably be more interested in the rules quiz we put together. We have 100 shots for you to call "fair" or "foul," in quiz format. Here's the scoring sheet. Here's the quiz video:


Here's the quiz answer summary sheet with all of the correct rulings (we think). Don't cheat ... take the quiz before looking at the answers. Here is a video that also contains all of the answers:


Again, don't cheat!

Please let us know how you did, and let us know if you have and comments, suggestions, or questions. Also, please let me know if you spot any errors. I put many, many hours into the quiz stuff, and there are bound to be errors.

Enjoy,
Dave
 
I haven't had a chance to view anything, but a special thanks for the effective mass of the rack video, and a general thanks for all. They promise to be very interesting.

Jim
 
Bob & Dr Dave,

I only got an 81, and feel fairly ashamed of my score. I thought I would do much better.

I want to thank you both for your excellent work putting this fine quiz together. It is obvious that it took a great deal of effort and the results are outstanding. I have no idea how many pool players will watch this, but I believe virtually all of them would learn quite a bit if they did so.

What I liked the most about your quiz was that it teaches how to call the shot correctly even though the shot itself takes place so fast you can't possibly see it in detail. This kind of thing is known by such a small percentage of players. They could be purposely hiding their knowledge because the call goes against them, but I prefer to give them the benefit of the doubt and say they are just lacking in the appropriate knowledge.

I've seen many people play at being a ref who have no idea how to call a shot properly. Maybe this will set them right. With my low score I guess 20% of the time I was one of those people and I know it has helped me to make far fewer errors going forward.

Thanks again to both of you for this wonderful quiz.

For those of you who like quizzes, I've got two on my blog, one on the 8 Ball rules and one on the General rules. They not video, though, just text questions. Just click on the quizzes link on the upper right hand corner of my home page.
 
Good quiz. I got 70 :l
The push shots are the most difficult shots to call. I would like to take a ref course eventually just to expand on my own knowledge of those shots. Thanks for posting.:thumbup:
 
I generally agree with your quiz, but no. 1, 15,22 where CB and OB are frozen I don't agree. The tip stays too much on the cue ball, due to the opposition of the OB so it is a push shot,there for a foul.
6.8 Push Shot
It is a foul to prolong tip-to-cue-ball contact beyond that seen in normal shots.
 
I generally agree with your quiz, but no. 1, 15,22 where CB and OB are frozen I don't agree. The tip stays too much on the cue ball, due to the opposition of the OB so it is a push shot,there for a foul.
Click to expand...

This has been examined on high speed videos, and it's clear that the tip does not stay on the cue ball more than a normal amount of time.

No foul.

pj
chgo
 
I have downloaded the Media Player but cannot get the topics to open. Any help would be appreciated from this friendly and knowledgeable group.

EDITED: Sorry about this post--My computer is just a little slow in loading. All is OK.
 
Last edited:
Klopek said:
Dr. Dave,

In "HSV B.47 - effect of shaft endmass and squirt on miscue limit", (in the final test), couldn't the increased squirt be directly related to the greater english applied?.
Click to expand...
That's a good point. With more tip offset, you get more squirt. However, if you watch all of the shots in the video, you will see that the cue with the added endmass had much more squirt than the cue without the added endmass, much more than can be explained by a small difference in tip offset. Also, with more squirt comes less English (for a given tip offset) because the effective offset is less. If you look at the stripe on the ball in the super-slow-motion clips, you will see that the CB actually has slightly more English with the low-squirt cue (due to a larger "effective tip offset"), even though the "actual tip offset" is slightly greater with the added-endmass cue!

Regards,
Dave
 
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Jal said:
I haven't had a chance to view anything, but a special thanks for the effective mass of the rack video, and a general thanks for all. They promise to be very interesting.
Click to expand...
Jim,

I look forward to your comments and questions. I'm also curious to see how you and others do on the quiz.

Regards,
Dave
 
Grampa000 said:
I only got an 81, and feel fairly ashamed of my score. I thought I would do much better.
Click to expand...
81 is probably pretty good for a typical player, but I'm not sure. That's why we are hoping lots of people can take the quiz (and help spread the word), so we can see what scores are typical. I would hope a typical referee could do a lot better than 81, but I'm not sure if that is the case or not.

Grampa000 said:
I want to thank you both for your excellent work putting this fine quiz together. It is obvious that it took a great deal of effort and the results are outstanding. I have no idea how many pool players will watch this, but I believe virtually all of them would learn quite a bit if they did so.

What I liked the most about your quiz was that it teaches how to call the shot correctly even though the shot itself takes place so fast you can't possibly see it in detail. This kind of thing is known by such a small percentage of players. They could be purposely hiding their knowledge because the call goes against them, but I prefer to give them the benefit of the doubt and say they are just lacking in the appropriate knowledge.

I've seen many people play at being a ref who have no idea how to call a shot properly. Maybe this will set them right. With my low score I guess 20% of the time I was one of those people and I know it has helped me to make far fewer errors going forward.

Thanks again to both of you for this wonderful quiz.
Click to expand...
You're welcome. Please help spread the word about the videos so more people can improve their knowledge. I plan to put out a set of detailed instructional videos (with added super-slow-motion video) to help people better understand exactly what to look for with different types of shots. I'll announce when the new videos are posted.

Grampa000 said:
For those of you who like quizzes, I've got two on my blog, one on the 8 Ball rules and one on the General rules. They not video, though, just text questions. Just click on the quizzes link on the upper right hand corner of my home page.
Click to expand...
Thanks for the info. I'll check them out.

Regards,
Dave
 
Dr. Dave,
You are the best!
Thanks for your efforts and contributing your information to others.
 
djpstacked03 said:
Good quiz. I got 70 :l
Click to expand...
Thank you for sharing your score. I hope others do also.

djpstacked03 said:
The push shots are the most difficult shots to call. I would like to take a ref course eventually just to expand on my own knowledge of those shots. Thanks for posting.:thumbup:
Click to expand...
Bob plans to use the videos when he teaches ref courses. I think the videos are also useful for players to improve their ability to make the right calls when a ref isn't around.

Regards,
Dave
 
madfox said:
I generally agree with your quiz, but no. 1, 15,22 where CB and OB are frozen I don't agree. The tip stays too much on the cue ball, due to the opposition of the OB so it is a push shot,there for a foul.
6.8 Push Shot
It is a foul to prolong tip-to-cue-ball contact beyond that seen in normal shots.
Click to expand...
Some leagues disallow frozen CB shots, but these shots are allowed under World Standardized Rules. As PJ has pointed out, there is no prolonged contact with a normal stroke into a frozen CB. Here is an example:


Regards,
Dave
 
Tennesseejoe said:
I have downloaded the Media Player but cannot get the topics to open. Any help would be appreciated from this friendly and knowledgeable group.

EDITED: Sorry about this post--My computer is just a little slow in loading. All is OK.
Click to expand...
All of the video links I provided go to pages with embedded YouTube videos. You shouldn't need the Media Player for these. Some people cannot view YouTube videos (e.g., because there is a firewall preventing people from wasting time at work). For these people, I provide an alternative interface which gives you direct access to WMV files, which can be viewed with the Media Player (so you CAN waste time at work). You can access the direct videos by going to the "alternative interface" links on my main video pages here:


Don't waste too much time (if you are at work),
Dave
 
Neil said:
You got me with the two unintentional miscues. I looked at them as scoop shots. Hard to differentiate without being there I think. You also got me on 4 of the frozen to the rail shots. The WPA rules don't seem to be very clear on the issue. At least, I couldn't find it. I remember that the cb had to hit the rail, or the ob be driven to a different rail. The same long rail, even across the side pocket, did not count for a different rail. Seems that in the WPA that is allowed, although it is not clear in the wording. Anyway, I scored a 91. (Would have been a 97 without those mentioned.:()
Click to expand...
Good job! This is the best score so far.

Concerning rail contact, the only requirement is that some ball (any ball) make contact with a cushion after OB contact. (A ball frozen to a cushion can't "make contact" unless it first leaves the rail and comes back). It doesn't matter if it is the same rail or not.

Regards,
Dave
 
Neil said:
On shot #37, I have to disagree with you. You called it a foul because the cb went too far forward. (jump-draw shot). I had called it good, then when I saw your ruling, I watched it about ten times hitting the pause button and play button as fast as I could. I agree it went a little forward on the shot. But that could also be due to the speed of the shot. I could not see a double hit. When in doubt, it goes to the shooter, correct?
Click to expand...
You are correct ... you cannot "see" the double hit, but Bob and I both agree the double hit is obvious with this shot. The cue is not elevated enough, and the gap is too small to allow the CB to hit the OB high enough to allow the CB to go forward that much with a single hit. With a single hit at that cue elevation and gap size, the CB would go forward very little. Try it out (with a jab or nip draw stroke). I think you can also hear the double hit in the video. Listen closely ... it sounds like the ferrule or shaft hits the CB.

Regards,
Dave
 
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