The Fascinating Physics of Bowling
A portion of this video was sponsored by Salesforce. This is the biggest, most in-depth video about bowling ever. How bowling balls are made, the best way to throw them, maximize strikes, how the lanes are oiled, what it takes to be a pro and how this sport has continually been reinvented for literally thousands of years, up to the present day. (bowling strikes) This is the science of bowling, the most popular participatory sport in the United States.
I'm super impressed with how that went. - I'm even more impressed than you are. - What is inside a bowling ball? I sent this ball to Creative Electron to get a 3D x-ray scan and this is the result.
What is that? I always expected bowling balls to be, you know, perfect solid spheres, but there's something inside here and it's not symmetric and it's not even centered in the ball. So I went to Storm Bowling, one of only 11 bowling ball manufacturers in the world to find out how bowling balls are made. - Yeah. Basically when we make bowling balls, we always start in the center and the center part of the bowling ball is the weight block.
And as you can see this is an example of an asymmetrical shaped weight block, so it's actually a different shape about the X, the Y and the Z axis. (serene music) - The weight blocks are embedded in a core of lightweight glass beads. - That is so silky-soft. I feel like I have not felt anything this soft. What's the difference in density between this sort of filling material and this core? - It's quite a bit. About two and a half to three times more dense in the inner weight block than it is in the core material.
- If you were to look for example at this actual core. Number one, it says 9 6 0 which means that it weighs 9.60 pounds. And then the description here underneath, which is a 0 3, this indicates what type of a weight block is inside of it. - What happens over here? - So this area right here is our urethane area. So basically what we have are a number of different tanks that are set up. So there's a chemical reaction that occurs once it actually fills the mold and we pour that cover stock material around the pour.
It gets extremely hot in just a matter of minutes. You go right down here, she's actually pouring the pin material inside the tops of those cores. So you can see for this particular bowling ball, it's a bright orange type of a material, and she's actually filling that hole with that plug material.
We've got the lane at the right here which is where we take the balls that come out of the mold. And then they actually spin almost 2000 RPM. On top of there there's the blades that come around and it actually makes the balls perfectly round. So they'll actually trim those up. - [Derek] Since the balls are not symmetric, they are heavier on one side than the other. - And you can see there the last four or five pumps of air, where it actually floats the air then it stops and pauses, that the ball has completely settled.
And then basically a needle will come out from the bottom part and all of a sudden it'll shoot it up. And then it'll be where the center of gravity is on the surface of the ball. - When it comes right off the lane, right here, it is extremely porous and very, very dull, and there is a ton of friction between the ball and the lane at this point. So every ball from right here will be smoothed up, it's just a matter of how much it's gonna be smoothed up in order to get what is the desired finish. - [Derek] But before they can use these balls, they have to be drilled. But that is specific to each bowler.
How many balls are you making a day? - [Steve] We're making over 3000 balls in a day now. they come out of this plant right here. (smooth calm music) - Wild. I found the bowling ball equivalent of clickbait. "You won't believe your eyes", "The mind bending hook". - Right? - Yeah.
It's how you have to sell your stuff. I get it. - Exactly. Yeah. - [Derek] But how did it come to be this way? Well, bowling seems to be an ancient game.
Archeologists have found wall drawings of a sport that looks like bowling in an ancient Egyptian tomb dating back 7,000 years. In Germany, bowling was used as a religious ritual. Pins represented your sins, so you're a good Christian if you could knock them all down. Martin Luther himself was apparently a bowling fanatic and fixed the number of pins at nine.
When the game made its way over to America, nine-pin bowling was banned because it promoted gambling. The legend goes that people cleverly came up with 10-pin bowling to get around the law. Whoa, totally different game. Today in the US, nine-pin bowling is only played in Texas because it was the one state that didn't ban it, instead, charging it tax. Bowling lanes are about three-and-a-half-feet wide and 60 feet long down to the headpin. I'm using Imperial units here because that's actually how they're defined.
The lane is made of 39 narrow boards that bowlers number for reference. They used to be made of maple and pinewood, but these days, most lanes are synthetic and made of fine particles coated with melamine resin. One game of bowling gives you 10 frames with two throws per frame to try to knock down all 10 pins. The highest score you can get in a game without a strike is only 190, but strikes allow you to double count your next two throws, so a perfect game with all strikes gives you a score of 300.
If you're anything like me, the whole game is just trying to throw the ball as straight as you can down the middle of the lane, hit the headpin and try to take as many other pins down with it as possible. Do you wanna give me any tips or- - I've watched LeBron bowling, you won't be worse than him. - You say that now you. (Chris laughs) - See, that's what I would normally do. And I would normally be like reasonably happy with a shot like that. But for pro-bowlers like Pete Weber or Chris Barnes, - [Narrator] For a perfect game, - Yes! - [Derek] The game is different.
And not just because they are way better than me. - [Narrator] And he get it! (crowd cheering) - Who you think that you are? I am. (crowd continues cheering) Hitting the headpins square on is not the perfect strategy. If you hit the headpin square on going straight, you're unlikely to knock down all the pins. You could end up with a split where the ball goes through the middle, or with the ball deflecting off to one side after hitting the headpin. Chances for a strike are much higher if the center of the ball hits the pins just to one side of the headpin.
Board 17 and a half. In which case the ball takes out the 1, 3, 5, and 9 pins, which take out the others. - So we want the ball to hit the 1 pin, the 3, the pin behind the 1, which is the 5 pin.
And then the 9 or the 8 and the 9. - [Derek] You want the ball to hit all of those pins? - [Chris] Yeah. - Now the pins don't always fall this way, but the pin shape helps.
Pins roll in circles like eggs, which help knock down the others. - That's right baby! Come on, don't miss. You wanted it, you got it. - [Derek] But to have an over 90% chance of getting a strike, the center of the ball has to hit with an error smaller than half a board. Needless to say, throwing a ball 60 feet straight at a target smaller than a dime is a tough task.
Especially to do it consistently. Luckily there is a better way. - Now, if we look at the pins and as you look at them from here, from straight on, the spot between the headpin, the one that's in the center, and the 3 pin which is just right at that, that gap's pretty narrow. But as the ball hooks more, now we basically shift over, and now that space is considerably wider.
- [Derek] If you can hit the pins not head-on, but at an angle of six degrees, you dramatically increase your chances of knocking them all down. Now the margin for error is greater. The ball can be coming in anywhere from board 17 to 18 and a half, that is a board and a half of room. And that still gives you greater than a 90% chance of a strike. Now, six degrees may not sound like a lot, but it's actually extremely difficult to hit.
The problem is, if you wanted to throw the ball straight at the pins and hit them at six degrees, you would have to be bowling from 3/4 over on the next lane. And that is impossible. Well, with the two gutters in between and all. So the solution is you've got to curve the ball on one lane. I feel like I have never spun a ball. Is that, (Derek laughs) Is that hard? - So if you've got it under your hand and the ball's underneath, and you're trying to spin it, that's especially the motion that players use these days.
- [Derek] This really became a big part of the sport by accident. - The wood gets beat up with the damage from all the balls going into it. And so they basically created slip agents, lubricants much like oil on a car so that the lanes didn't get damaged so quickly. - [Derek] So the original idea was to protect the wood.
- The original idea was just to protect the surface of the lane. It was not to manufacture anything for my competitive-scoring type environment. - But applying oil to protect the wood meant that balls no longer grip the lane and roll without slipping down to the pins. Instead they could skid, rotating not in their direction of travel. Now, I've been to a lot of bowling alleys before making this video and I noticed it was a bit greasy, but I always thought that was just the nature of bowling alleys.
Like the stinky rental shoes. I didn't know they intentionally put oil on the lanes. Vox has a great video specifically about oil patterns. These days, there are machines specifically for applying oil to the lanes.
- [Chris] And then as proprietors went, "Huh, well yeah, it does make the ball skid. Well, if I put more in the middle than the outside my baller's bowl a little bit better and they're happier." And then as technology advances like everything does now we have $30,000 lane machines that can put a specific amount of oil on each board.
- [Derek] They work kind of like dot matrix printers. They can lay the oil on with varying degrees of thickness across the lane and extend the oil pattern different distances. There are hundreds of different patterns that can be used. Usually the oil extends about 2/3 the way down the lane, so to around 40 or 45 feet. But there's always a dry patch of wood before the pins that increases the friction with the ball, getting it to start rolling without slipping.
And this leads to the three parts of any pro bowler's throw. The skid, the hook and the roll. When a bowler releases the ball, it can be going 20 miles an hour and spinning at 500 RPM. That's nearly 10 full revolutions per second. Right-handers typically throw the ball to the right on the lane while spinning it to the left. During the skid phase, the ball slides down the lane spinning but not rolling.
As it comes to the end of the oil, the friction increases and the ball accelerates to the left. It hooks because of its spin, and the spin starts lining up with the direction of travel, leading to stage three, roll. The ball is rolling without slipping as it barrels into the pins.
Ideally, as close to that six degree angle as possible. Like the ball starts on the left side of the lane, goes straight across almost rightmost. Then hooks like at the last minute, rolls in there. So that's almost like a perfect shot, right? straight in the pocket there. - Close. - Yeah. That's where you want to hit the pins. Yeah.
(ball hits the floor) - My very first game, it was ABC back then, American Bowling Congress. I filled out the application to bowl in men's league. Dad gave them the letter saying that I could, and the first game of bowl was 300 and they handed me a hundred dollars too, and it was like, yeah, making money now.
And actually, my first, my sixth, my ninth, my 13th, 17th, 20th were all 300 games. I like, seven or eight 300 in my first year of men's league. - [Derek] How do you explain that? - To shoot 300 you have to get lucky somewhere along the line. Like that. (Derek laughs) Like that.
It came in to hit the 1 3, 5, 9. And that that's what we call the perfect shot. - I mean, you just keep hitting them.
That's almost the identical shot. Look at that, that yellow and the purple, they're almost exactly on top of each other. - Oh, it just goes a little bit straight.
- That one, the purple one was just a little bit higher on the head pin, but it still hit the 1, 3 and the 5 and the 9. Can't get much better. - [Derek] This type of throw is only possible because of the oil. If you try to throw a ball the same way on an unoiled lane.
Oh no. It just doesn't work. Can I actually ask you to bowl like you normally would, but on the dry lane? I know it's crazy.
I just want to see what like a normal shot would look like If there was no oil. - No oil. It's gonna hit the lane and go in the left gutter. - That's what I want to see. - All right. You're gonna throw it just like it's a regular lane.
- Yeah. - All right. - Oh yeah, there's no oil on the lane so the ball can't get down. As soon as it hits the lane, it's going to start hooking, you know? 'Cause if you do this, who's skidding a ball on this.
- So they want the oil. - Yeah. We need the oil. If we didn't have oil, this is what it would be. And nobody would have fun. This is not fun. - The bowling sucks,
We don't want to do this. (Derek laughs) - For pro bowlers, the oil on the lane is a key part of the game. - Oh whoa.
- Wow. Hey. - Do you look at the oil? Are you trying to scope it out or are you just kind of guessing? - I usually don't look at the oil. I let my ball be the guide. You know, I know some guys that are, you know, they get down like this and they look in and it's like, oh, you know, they're seeing the same thing I do when I sit down, I go like that. Nothing. I see absolutely nothing.
- Whether you can see it or not, figuring out the condition of oil on the lane can make the difference between a strike and a miss. As the game wears on the bowling balls move the oil around, pushing it further down the lane and stripping it off the most common paths. So players have to adjust to the changing conditions. Some people say left-handers have an advantage because right-handers aren't playing on their side of the lane. At most bowling alleys, they use a pattern of oil that is thicker in the middle and thinner out toward the edges.
This is a forgiving layout because balls that drift too far out start to hook earlier, while balls going straighter can continue down the lane for longer before making their turn into the pins. But for pro bowlers, the oil conditions vary and players have to adjust their games to the conditions. Some people seem to think that like league bowlers are better than they are, maybe, 'cause they say like, "Oh, this league bowler can shoot two 10, and I just saw pro shoot two 10." - That's why they call it league because you bowl on the same shot every week. Because each week on tour, I'm bowling on a different condition. Not the same condition every week.
We have Cheetah, Chameleon, Scorpion, shark, one more. - Bear? - Bear. Yeah. - [Derek] But it's not just the oil on the lanes that is transformed bowling. It's also the balls themselves.
- Hard rubber bowling balls was what I started with. Maybe mid 70's and then the Yellow Dot, the Columbia Yellow Dot, which is a plastic ball. And then they came out with urethane bowling balls. I won a lot of titles with the urethane stuff.
And then they come out with the reactive resin bowling balls. - [Derek] Reactive resin is just a modified polyurethane with a more porous surface, which gives it more grip in the oil. It's the most popular surface or cover stock for bowling balls today.
Balls started out as perfect symmetrically-weighted spheres. And when you go to a bowling alley, the house balls there are still just that. But when you drill holes in the ball, you take some weight out of one side.
So to rebalance it, ball manufacturers added a small pancake weight on the same side as the holes. But then ball manufacturers got the idea, they could add different weights inside the ball to improve their performance. You can have two balls that look identical from the outside, weigh exactly the same amount, and yet roll differently. If the mass is more concentrated around the axis of rotation, say you have a dense cylinder inside the ball.
Well then it has a lower moment of inertia. And this means for the same amount of energy input, it will spin faster. In bowling, they prefer to talk about an analogous concept. Radius of gyration or RG.
If you were to concentrate the entire mass of the ball onto a hoop with the same moment of inertia, it's radius would be the radius of gyration. So smaller radius of gyration just means lower moment of inertia, which translates into more rotation that a bowler can get on the ball. - Some people are lower leverage it just spins faster, like, eh, it's of crazy, and then somebody finally did a study on that. Yeah, it turns out, yeah, it's like 8%, you know, for every 0.05. And so it depends on what your leverage is. Can be fairly significant.
- [Derek] An ability to spin the balls faster, gives a bowler the ability to hook the ball more sharply further down the lane, giving them a better chance of achieving that six degree entry angle. What was amazing for me to learn is that the weight blocks in these balls aren't even centered. There's a heavy side and a lighter side on purpose, and you can find and mark this side by letting the ball spin freely on a cushion of air, until it comes to rest, heavy side down. They showed me a great demonstration of how the position of the center of gravity can affect the movement of the ball. When the center of mass is on the left side of the ball, it pulls in the same direction as the spin, helping the ball hook to the left, into the pins, - Same exact ball, same numbers, just different static and balance basically. - [Derek] But here is a flipped bowling ball where the center of mass is on the right.
Now the ball starts to hook into the left, but at the end, something weird happens. The center of mass pulls it over to the right. This effect is only really noticeable when the ball is thrown slowly. These days, there are tons of different weight blocks that go inside bowling balls and they can be grouped into two categories, symmetric and asymmetric. For all these weight blocks, the minimum moment of inertia or in bowling terms, the smallest RG axis is identified by a pin, which is visible on the outside of the ball. It will spin most easily about this axis.
For the symmetric weight blocks. The ball doesn't change as you rotate it about this axis. So the maximum moment of inertia is rotating about any axis that passes through the equator of the ball. I certainly didn't expect bowling balls to have asymmetric cores, but it turns out what looked like perfect spheres, actually have three different principal axes of rotation.
Minimum moment of inertia, maximum moment of inertia and intermediate moment of inertia. - So this right here is our Dark Code. This is one of our asymmetric ball that has the Rad 4 core in it. So this has a preferred spin axis. And what we're going to do now is we're going to put it onto the determinator and show how it actually will spin it and find it no matter how we position it on there.
- [Derek] So you spin them up on this machine until they settle into the way they like to spin where the bowlers call their preferred spin axis or PSA. But why would you want a ball to be an asymmetric top? Well, professional bowlers drill their balls so that at lunch the axis of rotation is somewhere between the minimum and maximum moment of inertia. And as a result, as the ball goes down the lane spinning, it precesses like a gyroscope. The axis of rotation rotates around causing the point of contact between the ball and the lane to change. This precession means that different parts of the ball contact the lane.
And you can see this when the ball back by the spread-out lines of oil on the ball surface. Bowlers call this track flare, and it's desirable because it means once the ball hits the unoiled part of the lane, it gets traction faster and hooks more dramatically back to the pins. This is what asymmetric cores are used for. They have larger differences between their moments of inertia in different axes or what bowlers call RG differential, which makes the ball precess. If you spin a ball around it's minimum or maximum moment of inertia, it processes less and there's much less flair, meaning oil builds up on one part of the ball.
This reduces the friction over the dry part of the lane so the ball hooks less. - See the oil there, very faintly, but it's pretty much next to the finger, right next to the thumb, and it just continues to be right that way all the way around the ball. - [Derek] But how important are each of these factors in actually getting the best shot? Well, the US Bowling Congress, or USBC, the governing body that sets all rules and regulations for US bowling. They did a landmark study in 2008, trying to tease out the most significant factors that affect ball motion. In order to determine the impact of each factor, they had to make sure that throws were identical. So they turned to Harry, at the time, the most consistent bowler in the world.
He is a robot. Bowling robots are designed to be able to throw hundreds of identical shots. In fact, the robot Earl, Harry's successor in 2011, actually lost to Chris Barnes when he debuted in part because his throws were so consistent. He wore away the oil in a single part of the lane. So his shots hooked too much. The people managing him did their best to adjust to the oil conditions, but few people are Chris Barnes.
The USBC ball motion study used Harry to throw thousands of shots with different bowling balls. And they found that the center of gravity affected the ball motion relatively little. Around the same level as environmental factors like room temperature or humidity.
RG, and RG differential, essentially the moment of inertia and difference between maximum and minimum moments of inertia. That affected the ball motion significantly more. But the factor that affected ball motion the most was the surface of the ball. The top five individual factors were the amplitude of surface roughness, meaning the height of microscopic spikes on the ball, the coefficient of friction with an oiled lane, the surface roughness by spacing. That is the distance between microscopic spikes, the coefficient of friction with the dry lane, and how quickly the ball surface absorbs oil. Now, bowlers recognize just how important the surface of their ball is.
They pay close attention to what it's made of and how it's finished. Rougher finishes, give the ball more traction in the oil and get it to start hooking earlier. This is useful for long oil patterns and slower axis rotation. - Sometimes maybe I'll go to a little more sanded ball or a little more ball surface to get it into a roll quicker for me, because they use a lot of oil.
- These two shots are thrown identically. The only difference is the ball on the left has a rougher surface. Rough surfaces act like winter tires, helping to dig into the oil and give the ball traction. They also act as badly as winter tires on a clean road on a totally dry lane. They actually have less friction because their rougher exteriors mean that less surface area is touching the lane. You can get many different levels of smoothness up to a near mirror shine.
This is better for short oil patterns to prevent the ball hooking too much, too early. Ultimately, pro bowlers carry many different balls to each competition. - I'm not afraid to change balls in the middle of the game. I go to the game and I've got like a spare, a spare, a spare. All right. It's time to change balls.
- [Derek] Yeah. - So now I gotta find the right ball to get down the lane again and find the proper, which usually I have a pretty good idea. - [Derek] So they select their ball a little like a golfer selects their club, to suit the conditions. But does all this tech actually make people better bowlers? Well, over the last 20 years, average scores have increased by more than five points. Plus the number of perfect 300 games bowled per year per thousand bowlers has increased dramatically since the 1980s.
This graph shows the percent change year over year. In 1976, soaker balls, balls chemically softened to absorb oil and hook more, were banned, and there was a dip in perfect games. But the same year a new rubber ball was introduced, the Brunswick LT-48 and more 300 were hit in the years that followed. In 1991, reactive resin balls were introduced and there was another significant jump.
Now, obviously there were other improvements in equipment and natural variability, but some of the big changes do correlate with the introduction of new ball technology. So yes, the wild bowling ball technologies out there, especially anything to do with surface, significantly affect ball motion and your bowling game. But ball motion is likely minutely affected by hundreds of other factors. Even the color of the ball can have a small impact.
A USBC study in 2016 found that different pigments absorb oil at different rates. Bowling is the sport of re-invention. That goes back to ancient Egypt, but has transformed many times. Now, when you get up to throw a single shot, you have to think about the oil pattern on the lane, the stage of the game and how the pattern has shifted, the weight block in your ball, whether you want symmetric or asymmetric, which axis you'll spin it about to affect precession, where the center of mass is to pull the ball to the left, to the right, what the cover stock is made of and whether it's rough or smooth, all to make a shot that skids, hooks, and rolls to the pins between boards 17 and 18 and a half at as close to a six degree angle as you can master. Now do that again 12 times in a row and you have a perfect game. (techno sound effect) Hey, this portion of the video was sponsored by Salesforce.
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2021-09-26 20:45
