The Science of Curveballs
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- เผยแพร่เมื่อ 8 ก.ย. 2024
- For more info, please see www.physics.usy...
In baseball and cricket the best pitchers and bowlers know how to make the ball move due to the effects of aerodynamics. If one side of the ball is rough, the ball swings towards that side because turbulent air 'clings' to that side of the ball and is deflected. Although baseballs and cricketballs appear symmetric, they can be made to fly through the air with a smooth or rough side by judicious angling of the seams combined with the axis of rotation.
Steve Smith and David Warner liked this
Lol
Lolll
Lolllll
And put it to the test!
They are cheaters
I find this person quite relaxing.
2:30 This is why in baseball you will sometimes see the catcher hand the ball to the umpire who will look at it and give it back to the catcher, or more usually, give the catcher a replacement ball.
No, it isn't. Catchers hand the ball to the ump after a pitch goes in the dirt, because players don't like using balls that have been marked up by dirt. They never just hand a ball back to the ump. They're asking for a new baseball because the one in play is dirty.
This professor is so good all sports leagues have banned him
I tend to think it has to do with capillary action (or something like it). For a mechanical pump there should be no difference because pressure is independent of area.
????
@@the.aayushya thats how you reply to comments in the olden days
@@a1daid67 Thanks big brother
@@the.aayushya there was no reply button like today back then
But thrust varies with area
@bibabuzze No, they're due too the Magnus Force - check out our earlier video on this topic.
@jonasianbuddy Rod Cross, Emeritus Professor at the University of Sydney
Why there is no reply to this comment?
@@confused.cat.
@@confused.cat. Because "reply" doesn't exist when this was made
@@joerionis5902 Really? I didn't knew that.
@@confused.cat. Can't tell if thats sarcastic or true, lol
I know it's cheesy, but this video filled me with joy!!!
André Moraes that's ri8 bud....am a huge fan of cricket.....swing and seam always excites me
that's looking from the back - it's curving toward the rough side on the front.
Special appearance by zahir khan and R Ashwin
This video made so much sense! Cricket seems more sensible now!
@c3vzn Oh, the complications. Rod and I discussed this but you always have to limit the scope of a video. I think it involves the flow on both sides becoming turbulent.
ashwin? 1:46
@tanner9449 The diameter shouldn't matter but it did seem to be easier with 3mm (when we did the 6m attempts). For the 10.3m attempt, we tried the 5mm because we felt that was more in line with a standard straw.
its crazy how this only has 2 likes and no replies!!
This was a great video. Thank you. It would have been nice to have "reverse swing" dealt with. In cricket, with an old ball, some bowlers can get it to swing the opposite way. Any idea why this might be?
When you say "the opposite way" do you know what that means? Most people show that they are confused about it by saying stuff like "It swings towards the smoother side". That's not true. A ball ALWAYS swings towards the rougher side.
But in normal swing, this "rougher" side is the side with the seam. So the ball swings in the direction of the seam. Imagine an older ball (with one side smoother than the other) being bowled at the batsman with an inclined seam (as shown in the video). What happens with the older ball is that the rougher side, when facing the batsman, causes the air to become turbulent BEFORE it encounters the seam.
So now, when the already turbulent air hits the seam, it literally bounces off. So now, what WOULD HAVE BEEN a delivery that swung towards the seam swings AWAY from it TOWARDS the rougher side.
It's called "reverse swing" because without changing ANYTHING about their bowling actions, normally inswinging bowlers can make the ball swing away from the batter and vice versa. I hope I was clear with this explanation.
Unless most of a ball is uniformly rough except for a smooth patch, of course.
this guy seems to so positive, I just want to listen to him for ages.
Rod is just so full of charisma and smarts, must be an excellent person to hang out and chat with. Thanks for the awesome video!
golf balls and ping pong balls curve due to the Magnus force (check out our video on this) and the reverse Magnus force (haven't made one on this yet).
And as a further aside. I am Australian, that played baseball, that also went to Sydney Uni and this was one of my Physics lecturers while there.
So this video really resonates with me.
What you explained with the cricket ball was the conventional swing. Can you please provide an explanation for reverse swing that happens once the ball gets older?
the bowlers maintain one side by polishing it and allow the other side to deteriorate and become rougher. They can then choose the direction of the swing by just deciding to have the smooth side on the left or right.
+Dinsdale Drummond that's not correct reverse swing is when the ball usually a ball of around 50+ overs old will start to swing the opposite direction e.g. Towards the shine and away from the rough side. As far as I'm aware no one has been able to comprehensively explain this phenomenon.
Jon bell this video just comprehensive explained it
no, this video explained conventional swing with regard to the cricket ball - it did not explain why after becoming old a cricket ball starts swinging towards the shine - do you play cricket ?
@@Jonno_B251 I think the reason might be that, by that time the rough side would have shed a lot of material that the smooth side will be heavier in the air. So this weight difference might override the turbulence effect explained here, as the ball gets older.
i recently realized that this described a curve i throw in slow pitch softball... you finally helped me solve the riddle of why this pitch curves since i don't crank it at all... i knew something else was at work and now i know what it is...
i started out to hold a clinc to teach what i do without knowing why it works... and in researching it i found your video which i had seen before but didn't realize what it meant to me... once i realized... i started figuring out what i could do to make it work better and more consistently... and it assisted me in teaching it to others at the clinic...
you should look into this...
thanks again... 8|
wow, as someone who played baseball for most of my life, this blew my mind. The different baseball pitches and how they worked always seemed pretty straightforward, but then there were times you'd hear about a particular pitcher having a lot of movement on the fastball or having "late movement". And this effect could probably partially explain why. So many intricate air flows going around a baseball.. this also sheds some light on the knuckleball, too. And it's making me think of the long-derided "gyroball" from japan..
How is this doens't have 1 million views😌👏 just brilliant👏👏👌👌👌👌👌
Brilliant - you said you'd do this and you have! I think at last I'm understanding how Shane Warne produced his ball of the century and it seems that swing (Seam bowlers) and Drift (Spin Bowlers) both optimise the laminar flow and boundary layer factors to get the ball as Grimmett would have called it to "Swerve".
When I used to play baseball, I had a lot of movement on my slider.
I am right-handed and I had my fingers such that if you hold the baseball in front of you, so the seams makes a "U" shape, I positioned my fingers together just on the inside of the right part of the U and threw the ball with a slight wrist tilt on release, which produced the rotation shown.
At the time, I didn't realise what it was I was actually doing. So I'm glad this video finally explained it to me many years later!
Can’t believe you’ve been doing it for 10 years! Amazing
Science + excellent presentation x amazing guest speakers + epic beard = fantastic show !
Just to get the baseball jargon correct: The "curveball" that they talk about at 2:07 is actually not a curveball but a slider, which breaks mostly laterally. The curveball's dominant movement is downward, due to the top spin imposed on the baseball by way of the pitcher's delivery, which basically pulls down at the front of the ball when he throws it. Some curveballs do have lateral movement, but the essential break is downward.
The purpose of a knuckle ball is to give very little spin to the ball.
So the perfect knuckle ball initially has no spin.
If the ball is perfectly round and smooth it would move normal.
A ball isn't perfectly round and smooth, it has all sorts of bumps, scrapes or seams.
This, together with drag, will make the ball rotate. Also the bit from 2:50 on is still valid.
So the ball will swing away from the smooth side, which will change as the ball is rotating. Which makes for a erratic flight path
High five, Derek! Great job!
I used to play baseball all the time and they told you at least how to hold it to get it to either be a slider or a curve, etc.. but they never explained why. Cool video.
What is the ideal angle for a spin bowler (in cricket) to spin the ball on to get optimal swing/drift?
How does the amount of revolutions on the ball affect the amount of swing/drift?
Swing is a subtype of fast bowling swing bowling is to get the cricket ball to deviate sideways as it moves through the air towards or away from the batter
@DreJr a football ( i am assuming you mean the spherical one, if not then its just aerodynamics i think ) then the magnus effect is responsible for 'swerve' , air has friction, and the side spinning with the headwind is the direction of motion. (im 17 so sorry for poor vocabulary and explanation)
Great youtube channel. I subscribed a few months ago, and since then there have been several gems. Keep them coming.
reverse swing is caused by the rough side of a cricket ball becoming lighter than the shiny side because of the material lost off the ball. he ball will fall towards the shiny/heavier side
Great video. The professor is a joy to watch and learn from.:-)
This is excellent. We will use this in future BallsAustralia exclusives.
Plus with an aircraft's wing in a wind-tunnel it can easily be demonstrated that NON-laminar air detaches from the surface quicker (hence stalling and so on).
Found your channel tonight. Love it. Thanks for putting something educational out there. I love science and physics... I’d like to get my daughter in love with it too.
what about reverse swing?
You reverse the ball. It's a bit hard to explain this way via writing but changing the shiny side and seam direction makes it happen. That's just the ABC. Usually bowlers change the shine direction during run up to confuse the batsmen on striker and non striking end. It's not rocket science but not easy to explain here either. Hope this helps.
Works on the same pricipal at 1:48 ...just that the seam of the ball is parallel to the wickets when viewed from the bowler's end..
although at the point in the flight where the arrows are displayed the forces may be about equal, and as the orientation of the ball changes later in its trajectory the side force increases causing the ball to curve "late".
I could watch this all night xD It's almost 1:30 pm... Alright, last video! :D
Totally agree with you still, but check out a knuckleball in slowmo! That's where it gets truly mindblowing to me.
I'm sorry if I sound dumb, but what about the Bernoulli's principle?
If the air passes through the rough side of the ball, then it will meet greater resistance, right? (I'm actually not sure about it).
Then, according to Bernoulli's principle, the fluid(In this case, air), must exert a greater force on the ball than the smooth side.
This should make the ball swing towards the smoother side.
Could anyone please tell me why this approach is flawed or if the assumption I've made is wrong?
exactly what i was thinking and what i had been learning from other vids.
No its not flawed, both effects are in place of course.
Same is the case with the aerofoil, you have Bernoulli and the Third law together gives the lift!
Your understanding of Bernoulli's principle is a little off. What it says is (in the case of the ball) the air will travel faster because of the roughness (roughness can be attributed to friction, but nor really in this case) causing more terbulance, meaning air traveling faster.
This will cause low pressure on the side which is rough and and the ball moves in that direction.
Remember, the key is that on the smoother side air travels slower creating more pressure and pushes the ball causing it to swing.
I would like to start by clarifying the deference in resistance, applied on a ball, between a laminar flow and a turbulent flow.The laminar flow creates a bigger wake behind the ball than the turbulent flow, resulting in a larger drag force applied on the ball. A smaller wake behind the ball also explain the longer period in which air ''sticks'' to the ball (the difference in separation point). Another very important thing to note is the misconception around the Bernoulli's principle. Firstly is that you CAN NOT apply Bernoulli in turbulent flow. The assumptions of Bernoulli's principle are: STEADY FLOW, IN-COMPRESSIBLE and IN-VISCID. In this case the flow is NOT steady, it is also NOT in-viscid. It is dangerous to apply Bernoulli if you don't understand it properly. Usually Bernoulli is used for finding values around the real ones and that is mostly because of the in-viscid assumption. The Magnus effect is given because of the curvature of the flow that creating a change in momentum of the flow and that resulting in a force on the ball. No Bernoulli just change in momentum.
0verkilled you have just said the opposite. bernoulli's principle - increase in speed will lead to decrease in pressure, vice versa to achieve lift, wings are designed in such a way to more wind speed on top of the wind compared to bottom.
You talk to such interesting people over interesting thing!
Really interesting! Excellent explanations for a complicated phenomenon.
Btw, in the presentation text:
defelected -> deflected
We need more scientists like this nice gentleman!
Curveballs generally do not have lateral movement. While there are a ton of breaking pitches and even more ways to blur the lines between all of them, the curveball is generally meant to mean a pitch that breaks from 12-6. It is thrown by providing top spin and making the laces tumble consecutively. As proven by a ton of other ball mechanics, top spin provides more drop off in trajectory. The pitches shown and discussed in this video are more akin to sliders. This difference is the reason why curveballs are what ruin pitchers rotator cuffs more so than any other pitch. To produce the top spin, you align your index and middle fingers on a single seam and as you throw the ball, you turn your wrist sideways and yank downwards. Very few curveballs have perfect top spin and are usually rotating at an angle. This leads to the famous "red dot" that batters will see while the pitch is on the way.
this bloke is so australian
Okay, the pitcher at the end of the video clearly has a splitter grip, and the action is what you'd expect from a 3/4 or sidearm split-finger fastball. I always thought, though, that the splitter did what it did because there was less backspin (magnus effect) keeping the ball afloat than a usual fastball, without too much dip in speed. However, that seems like it only explains the action from a 12-6 overhand throw. Or is the action more similar to the gyroball? I'd love to hear from a pitcher about what I'm seeing there. Fascinating stuff nonetheless!
i think he's explaining why the cricket ball swings, ping pong balls and golf balls are made from different materials and dont have a seam around the equator of the ball and requires a lot of force to create sidespin. Its an apples and oranges kind of deal.
It's called a xistera. It's used in the game "Jai alai".
en. wikipedia. org/wiki/Jai_alai
Your videos are awesome. Just need to be more clear on left and right otherwise it does get confusing. I have seen this in more than just this video of yours.
Let's not invoke the classic "why does a mirror switch left and right but not up and down"....no wait, lets do! Make a video on that for fun.
Bernoulli's Theorem works off the streamline flow of an ideal fluid, which air definitely isn't. If it were, the air would just pass straight over the ball, seams and all, and carry on as it was out the back. And due to the balls symmetry, there is no real difference in distance, and therefore pressure on either side of the ball. Any effect from Bernoulli would be outweighed by the large amount of drag produced by the seam.
how to curve a ball?
simple. just throw it like you normally would. the coriolis effect will curve it either right (on the northern side of the globe) or left (on the southern side of the globe)
@pinkybrain6 I would of thought it would be due to the fact that more friction is caused by air running over a rough surface e.g its hard to walk on ice due to lac of friction so you "pass over quickly" whereas its easier to walk on a pavement as there is more friction as it is rougher so you "stick" to it. I hope that makes some sort of sense.
Waseem Akrim is famous for roughening up a side of a cricket ball and using it to achieve reverse swing. Most world class fast bowlers also have a specific gripe for reverse swing. When we play a cricket match, our team makes sure the ball bounces as little as possible and we always shine the side with the logo. I am curious as to how this effect would affect a spin bowler. Anyone have any idea?
Rod seems a really nice chap and very intelligent too!
Hey Derek, who is your go to cricket player?
Very cool!
people still asking about "reverse swing" clearly didn't pay attention to the video. It's all the same effect, just that in the reverse swing case, your seam is not as prominent, and the swing is caused by one side being rougher than the other.
Lol, this video is right at the intersection of my interests: mechanics and baseball. Derek obviously knows a lot about the former, but probably not much about the latter. As such, here are some corrections:
2:06: A curveball doesn't usually spin on a vertical axis. Though every pitcher is a little different, the term "curveball" refers to pitches that have some degree of topspin. So, with some variation, the axis is horizontal, and because they have topspin, they fall faster than gravity pulls them. They also move in varying degrees to the pitcher's glove side, so to the left if thrown by a right-handed pitcher. A curveball that moves to the pitcher's arm-side is called a "screwball". I think they are called "curveballs" because their movement is most noticeable, because their movement is consistent with gravity. The fastball, on the other hand, resists gravity, due to backspin.
2:33 In major-league baseball at least, they put a new ball in play if virtually anything touches the ball, other than the pitcher and catcher. Pitchers don't have much opportunity to scuff or smooth a baseball, because they're almost always using a new ball.
3:18 lol "baseball match"
Joe Alias Yeah I was very surprised to see that cricket balls stay in play the entire game! And I'm glad someone made those corrections :P
Joe Alias I've always thought of the prototypical curveball to be the 12-6 curveball.
Ben That sort of curveball I think is often considered the "ideal" curveball, but rarely do pitchers ever throw that pitch exactly. Almost always, a curve has some sort of horizontal plane as well, making it more of a '11-5' or '1-7', as people say. Some of the best curveballs in baseball, like Adam Wainwright and Jose Fernandez right now, have significant horizontal movement.
Soccer Ball swings because of bernaulli effect. And it swings towards the laminar flow. You seem to suggest that cricket ball has opposite effect.
OMG! This man, is awesome
please correct it.. for cricket ball, the rough surface side generates high air pressure, smooth surface side generate low air pressure, so high pressure pushes the low pressure, and ball swings in air in smooth surface side.
@bibabuzze Remember Jabulani, from 2010 World Cup? That ball was tricky...
3:39 lol. Dude your vids are great. Thanks for the good job you do!
The explanation takes more room than a TH-cam comment allows. Follow the link under the video, click on the picture of the baseball then the link to an article on knuckleballs.
Would like to know the guests' name!
A few people have mentioned that a pitch with a vertical spin axis is a slider. Actually, that's not quite correct. Most sliders have an axis that is parallel to the direction of motion, sort of like a corkscrew, or a bullet. This makes them move somewhat close to how a thrown ball would move in a vacuum, at least more so than any other pitch.
A few pitchers throw sliders/curves with a vertical spin axis, like Sergio Romo or Adam Ottavino, but they tend to have nearly sidearm deliveries. It's very hard for a pitcher who throws overhand to get that kind of spin.
However, there is another pitch that tends to have a vertical spin axis, but with the spin oriented the other way: a circle changeup. Most circle changes move way more to the arm side than sliders move to the glove side.
Joe Alias I played houseleague baseball a few years back, and aside from a fastball those two pitches (the one shown and a circle change) were the only two I knew how to throw with any effectiveness.
MrYeshi412 that's cool, a circle change is usually pretty hard to throw.
It felt really weird in my hand and took a while to get a hang of, but my brother showed me it when I was a kid so I had quite a bit of practice
thanks for the true information guys
could you explain how reverse swing works? wasim akram and waqar younis were the first to demonstrate this very effective tactic in the 1980's
In the sister video to this one, you used the term "parabolic" when you described the tennis ball falling. So much of this universe ends up following a parabola or shaped liked one. Why not have a video about what they are and how so much ends up having one or moving in its shape?
golf balls and ping pong balls both show curvature due to spin and neither have a rough surface. The symmetry of a baseball is such that the seam makes no difference. I went through every comment and nobody is questioning the science in the video. Am I crazy? (I liked the video)
Found it (using Shazam) for anyone wondering, the song is Opus Magnum Phase - Le Dernier Orage
Bancroft has entered the chat.
You just nailed it
3:40 that was so wholesome
@SteinPapier Because the flow of particles is deviated and less smooth :)
Thanks, I just bowled out my friend in cricket multiple times using this video. Hint: He was VERY mad...
this was put up on my b-day :D great vid btw
With the Magnus force, why would the "speed" (or spin) change how much curve the baseball has?
Let me c it this help me in my game... Tnx for the info Prof.
In regards to Cricket, which way should I spin the ball, (I am a Leg Spin Bowler) with the shiny side facing the batsman or the rough side?
You don’t necessarily need to, but I’ve bowled spin with a tape ball, and it kinda… reverse drifted. Might have been the breeze though.
thank you for sharing this amazing video
I would suggest coloring the cricket ball differently based on the side that is smooth, because the game is biased in favour of pitchers and bowlers.
Can you make a video explaining why a plane is affected by turbulent air and why it's bad for a jet to fly in the path of another jet?
Hooray for learning!
This old guy is a genius.
Awesome accent :) Love it ^^
I'd say it'd depend on weight, fabric, speed of the ball thrown.
i love cricket
did I hear them correctly? If the seam is not rotating parallel with the motion of the cricket ball the ball swings to the smooth side and if the seam is rotating parallel the ball swings to the rough side? 1veritasium, can you put annotation arrows on the diagrams? I'm confused.
a spit ball has been around for quite a while though.... I assume that is 'smoothing one side" not causing drag...
I think that was Aswin in India - Australia Match
I love your whitecaps FC jersey. One question I have is what about curling stones. Because they rotate the same direction as the spin. Is this from having a smooth side or because of a different effect?
I have that same fusion poster @ 3:14 !!!
Why doesn't Bernoulli's principle work in this case? As pressure will decrease on the smooth side due to the increase in velocity, so why doesn't the ball curve towards the smooth side?
May they be well and healthy.
Clearly, the pitch being thrown at 3:21 is a split-fingered fastball. That is NOT considered a breaking pitch. It is more of an offspeed pitch that has movement due to LACK of spin, much like a knuckleball. It's a slip pitch! In essence, a split-fingered fastball is nothing more than are REALLY fast knuckleball. A knuckleball may have 1 or less rotation from release to the catcher's glove. A fastball or curveball is going to have over 10 rotations (or more). An extreme version of the split-fingered fastball is the forkball. That pitch has even LESS spin.
The pitch in the video makes about 5 rotations on its way into the catcher's glove which makes it a hybrid between a high-rotation pitch (fastball/curveball) and a low-rotation pitch like the knuckleball.
It's a bad example for what they are talking about in this video. It would be like showing behind-the-pitcher shots of Tim Wakefield pitching. You would see dramatic movement of the ball but it certainly wouldn't be because of the Magnus Force.
David Emerling I think you're almost right. Split-fingered fastballs tend to spin less than most pitches, but not nearly so little as a knuckleball. A knuckleball, by having so little spin, is inherently unpredictable in its movement. The is no consistent axis or orientation of the seams, meaning that the ball may move in different directions in one trip between the pitcher and the catcher. This is why catchers hate catching knuckleballers; not even the pitcher knows what direction the ball is going to move.
Splits are not quite so unpredictable. They spin, but just not nearly as much as a fastball. Fastballs spin a lot, with a lot of backspin, which gives them rise. Splits, which are sometimes considered a type of fastball, travel almost as fast, but less spin leads to less rise. This means they tend to "drop" relative to the fastball. If the pitch looks like a fastball coming out of the pitcher's hand, that difference in movement can disrupt the batter. However, they do spin enough that they are not quite as unpredictable as a knuckleball. The knuckleball can cut, tail, rise or drop, whereas a split tends to tail a little bit and rise a little bit.
David Emerling In reference to the example, the pitch is a splitter, but the rotation axis and the seam-orientation is the same as for a two-seam fastball, which do move the arm-side, or the direction of the Magnus force, as seen in the video. So indeed, the pitch is definitely moving in an unexpected direction.
I would also add that, for these purposes, the distinction of "breaking pitch" is somewhat misleading. Basically all pitches "break" in some direction. Fastballs move upwards to due magnus force, far more than sliders do, for example. Sliders are considered breaking pitches, but their spin axis is actually parallel to the direction of motion, like a bullet, meaning they are less affected by the air than other pitches. The term "breaking ball" refers more to their effect on a pitcher's repertoire than to how they actually move.