The physics analysis assumes that not only are the balls elastic, but also that there is no friction between them. Even in a good poolroom that cleans their balls often, there is a little bit of friction which causes the "throw" effect. So for a half ball hit, at the time of impact the centers of the balls are aligned at 30 degrees from the initial direction of the cue ball, but because of the throw effect it will end up traveling about 27 degrees relative to the initial direction of the cue ball. This can vary depending on how dirty or greasy the balls are. So the balls separate at about 87 degrees (assuming no inside or outside English). Sorry for nitpicking; this is a great demonstration, and the 90 degree rule is still a good approximation to be very useful at the table.

OMG!! My inner nerd practically lept out of me when you said "vector"! What an EXCELLENT explanation with the most mathematically, geometrically and physics correct terminology! Thank you!!

Definitely can't argue with the evidence provided here!!! Either by mathematical expression or diagram illustration, one backs the other ... awesomely great visual tool to see what is actually going on --- with result. In general -- the "resulting" ACTION is exactly what can be EXPECTED (very similar result). Brilliant my friend --- Priceless info!!!!

Excellent!

Those were *excellent* graphics and explanations!

Great experiment and illustration 👍🏻👍🏻👍🏻

Thanks so much for putting the time and editing effort into this. Explained for me why my soft shots weren't ending up at the end of the tangent line.

@brett6314

9 ай бұрын

Watched again; so much content to absorb. This time I'm debunking the rolling ball "peace sign" to predict cb travel. The way Dr Dave has it shown is from the ghost ball center. Really the roll should be up the tangent line with the distance depending on speed. His experiments showed an overall range of angles that are mostly at 30 degrees. Your examples add to it.

Thanks sir, that was really helpful for me to do my calculus assignment!

It's a well known method to use running english to allow for a thicker hit so that you can draw more straight back and so on. However, I think it's less common to see people doing the opposite to allow for a thinner hit when that's needed. Stunning with a hair of inside would allow a thinner hit if you find yourself too straight on a ball. I use it from time to time.

Hey Bob , great video ..Dr Dave’s wagon wheel drill a great exercise for this

One has to account that then using low right or left with the same force, the draw spin is lessen by that compared to just draw at the same low spot but without English.

Bob, Howdy; Interesting video, I'd like to see what the results are after you've shot at least 10 of each. chuckle. Inital direction may be 90* however, as each variant moves more then the first 1-3 inches they then assume their own track. I was also very happy to see that you were not using a line from the edge of the Object Ball, but were starting the Tangent Line from the center of the cue ball as a lot of folks don't realize. Good Positive reinforcement so they can plan more accurate shots.

great visuals! That last part with the star wars reference got me laughing! XD

@ShortstopOnPool

4 ай бұрын

Star Wars nerd here. LOL

Fantastic video. Liked, subbed!

@ShortstopOnPool

Жыл бұрын

Thank you!

Pool is a 4D visual intuitive game.. I use the tangent line, "ghost ball" all the time👻🎱

You should represent your slow "stun" shot hit with some low english, to where it is sliding on impact. That would make it a true stun shot, and follow the tangent line for the remainder of the roll.

Im a fan

the very first example (and subsequent shots), the cue ball was rolling, which is why it didn't go down the tangent line.

Fact.

Hey Bob you always shoot pool barefoot 🦶 !!! @7:45

@ShortstopOnPool

Жыл бұрын

Usually I wear socks! LOL

@tmangan327

Жыл бұрын

@@ShortstopOnPool 😆 🤣 I wear house slippers

This was good and as expected. I would point out that I believe a bar box cue ball is heavier than the object balls because of the magnet in the middle.

@ShortstopOnPool

2 жыл бұрын

Back in the day they were even bigger and heavier. We called them "mud balls". Shooting with draw the cue ball would roll forward before the backspin took and it came back. LOL

@markinjhawkland724

2 жыл бұрын

@@ShortstopOnPool yes they’re still around. Cue ball is 1/4 inch larger diameter and a lot heavier. I won’t mess with them.

@RadioTom103

2 жыл бұрын

On modern tables the magnet is in the table. The cue ball has a metallic coating under its outer skin. I don't believe the weight of the cue ball is different from the object balls. This would be easy to verify with an accurate scale.

Bob, I think it’s more important to feel the shot than know the the physics of numbers for cue ball response as there are more. Important things to be thinking than numbers and degrees etc…etc….while stroking the cue ball.. One’s kinesthetic senses rule over technical knowledge in this game of pool. I know you can’t do without some knowledge, but practice rules.

@SenseiNatePlaysPool

2 жыл бұрын

I think nearly everyone would agree with this statement- but I don't think Bob is saying not to rely on the feel of the shot. He's simply making a case for the points he's making- which you can't do by saying it "feels" right.

@ShortstopOnPool

2 жыл бұрын

What Nate said. I agree with you 100%. But beginners often have trouble understanding the tangent line. Having the foundation of this video helps them when practicing and building up that "feel".

@brett6314

2 жыл бұрын

Idk, I've been pretty baffled why my shots aren't following the tangent line. Now I see why. I'm a soft to medium hitter. The cue ball is picking up forward because of the speed for me.

Hi Bob. I appreciate your videos. No matter how many years I’ve played and improved, I practice humility and review aspects of pool I “already know” on KZread and on the table. I wonder if you could follow up with shots utilizing an elevated cue. (I vaguely recall a Buddy Hall video depicting interesting effects). And, how are those shots utilized on shallow and sharp angles into a rail for position play? (I have used inside English on shallow angles to reduce rebound off the rail.) Also I see pros make certain shots that I can’t explain. Not just draw but follow into the rail that opposes the natural path. (Excuse me if you already have a video on this.) PS: The Z shaft isn’t relatively a popular shaft but I also play with one. I really like the precision but have a bit of dislike with the relatively lesser power transfer and unforgiveness with straight shots. (Left-handed, right eye dominant, my stroke crosses left to right) Thanks for the great videos.

@ShortstopOnPool

Жыл бұрын

Gonna have more time and better setup to address more topics....soon....

Nice job Bob! Put those naysayers to rest! lol. My ONLY question this this. With OUTSIDE spin on a MAXIMUM draw shot, you'll always get less backspin because the striking zone on the cueball is circular. The more to the side you strike, the more you're forced to strike higher on the ball. I'm sure there's no argument against that. So the question is...How confident are you you're hitting maximum spin on that pure draw shot vs draw with outside? I get that the spin induced throw allows for a fuller hit, but are you saying that fuller hit is enough to counteract the backspin you lose because of the altered tip placement? I also understand this depends on the stroke, elevation, consistency, cleanliness of ball, cloth, etc...

@ShortstopOnPool

2 жыл бұрын

Yeah, good questions. I tried to keep this video basic to make it accessible to everyone. And honestly, I need to do more research before the next video.

@SenseiNatePlaysPool

2 жыл бұрын

@@ShortstopOnPool Totally understandable...Can't wait for the next one!

The 90 degree rule is one of the great myths of pool. Thus is because the collision is not perfect (physics). The accompanying myth is the center ball hit. In realty the cue ball must be struck very slightly below center to yield a perfect 90 degree tangent.

Great video, thanks. On all pool tables I play in the UK the cue ball is smaller then the play balls, how does that effect the angles?

@ShortstopOnPool

Жыл бұрын

The geometry is the same no matter how size of the balls.

@b18craz

Жыл бұрын

As long as the cueball and object ball are the same mass…

In your example, you said you were using inside English but then you said that you put right hand English on the shot. If you are cutting the object ball to the left, then inside English would be left hand English. Correct?

@ShortstopOnPool

Жыл бұрын

Sometimes I have verbal dislexia. Try to correct it but sometimes miss it. Yes, a cut to the left means left is inside English.

@midnightmadness406

Жыл бұрын

@@ShortstopOnPool thank you! I just wanted to clarify. Thank you for your videos!

It pays to have paid attention in physics and geometry.

Yeah, some pool teacher he is.. can't even tell a 9 ball from a cue ball!.. jk. Wish i was good. Just got an 8x4 Olhausen and trying to hit the cue ball where i want to pocket the object ball is very difficult. It's much easier in pool video games.

Hey Bob, could you tell me wich glove you are wearing and where to buy it? Good video again, cheers :)

@ShortstopOnPool

2 жыл бұрын

It is a 3 Seconds glove. After three months of use the top of the glove still looks and feels brand new. But the bottom is now wearing through like every other glove I have owned. I like the way it fits and the fingers are better than any other glove I've tried, only now just starting to separate a bit at the ends. So it has lasted twice as long as any other brand, but they still need better materials, IMO.

@mr.lootybutthole

2 жыл бұрын

@@ShortstopOnPool thx for the response :) yeah i was wondering, because i am on a years long quest to find a durable pool glove, like probably everyone else :D

@ShortstopOnPool

2 жыл бұрын

@@mr.lootybutthole I can only assume they want them to wear out so you buy another. So even though I love the 3 Seconds glove, I won't spend more than $10 anymore.

@mr.lootybutthole

2 жыл бұрын

@@ShortstopOnPool i think you are right. I really appreciate your videos btw. I always loved 14.1 but, my skill didn't match with my rotation performance. Since i started applying your tips, i skyrocketed. Made a new high run and just a couple of hours ago, made my first race to 125 in 9 innings winning against our strongest player in the club (also first time). I owe this to you man :) looking forward to buying your book.

So if the cue ball is bigger then the object ball, there is a different result?

@ShortstopOnPool

2 жыл бұрын

Oh, yes.

The tangent line doesn't change at all. The English your putting on the ball stuck, is manipulating the tangent line which it always does and is the reason we use English while playing billiards