physics of bowling

It’s been a while since I’ve seen pro bowling on tv, but I seem to recall these pro bowlers (who can nail strike after strike) usually putting a lot of “English” on the ball, so that it rolls out toward the gutter and then curls back into the center.

Why? Why does this work better than simply rolling the ball straight down the center of the lane?

Actually, they generally don’t roll the ball towards the gutter and make it curve in - they release the ball along the gutter edge and then let it curve in. Before I answer your real question, let me tell you why it won’t work the other way.

The bowling lanes are oiled. They are heavily oiled near the release point and gradually less and less oiled near the pins. This is so that a curve will be mostly ineffectual until it starts to near the pins and so the ball doesn’t lose it’s spin in the early stages of the bowl. A good curve ball starts on the edge of the gutter and starts to break about 2/3 to 3/4 of the way down the lane. It strikes the head pin at about a 35 to 40 degree angle.

Why? Two reasons. One, it’s nearly impossible to consistently hit strikes with dead on balls straight down the alley. A perfectly centered ball will consistently leave pins standing, usually in some sort of split configuration which then makes it harder to pick up the spare. Unfortunately, the physics are difficult to explain without drawing some pictures; you’re just going to have to take my word for it. Second, when you hit the pins from the side you get more “pin action” from the pins bouncing off the sides. Watch a straight bowler for a while, then watch someone with a good curve. What you’ll notice is that the guy with the curve is often knocking down pins on the right side of the lane with pins that bounced off the left wall.

I bowl with a very aggressive curve. Only my thumb goes in a hole, the rest of my fingers are palming the ball. This is so I can get a lot of spin on the ball without wrecking my wrist. I get so much spin and such a hard curve that it’s not uncommon for one of the pins to come spinning out into the lane, though normally I prefer them to be spinning in and amongst the other pins.

Actually, Joey is pretty close to correct, but there are some things that need to be clarified, IMHO.

First of all, when a modern professional bowler releases the ball, he often WILL aim at the gutter, since the spin placed on the ball and the speed of the ball down the alley won’t allow the ball to start straight along the boards next to the gutter. Earl Anthony had a straight down the alley release, but often today the ball is released at the second arrow or further in, and rolls out to about the 2 or 3 board before it snaps back to the pocket.

Now, to answer the original question: Why do the balls get thrown with spin instead of straight into the pocket?

There are two reasons for a curved ball being better. One reason is that a greater angle of attack can be achieved, which is preferable as you will see. The other is that a curved ball often still has a component of spin, which helps make the pins mix up more as they are knocked off the end of the lane.

The angle of attack thing, though is the main reason for curves. To understand this best, you have to draw a mock up of the pins and the ball. A ball coming at a relatively straight angle can’t send the One or Three pins back in as effective a combination of angles, nor can it then continue through to take out the five pin and eight and nine pins as easily. A ball with a large curve will come into the one and three pins with an angle that sends the one into the two, off the side and into the four and seven, the three into the six, which one HOPES will then take the ten, and allows the ball to drive on through the five and take out the nine while the five takes out the eight, or vice versa. The most typical leaves on such a ball will be the ten, when the three sends the six around the ten, or the seven, or even the four-seven, when the two is sent too wide.

All good and and correct from both parties, except for where the ball is aimed.

It is aimed wherever it works. That depends on the bowlers style and lane conditions. Someone who is a real “cranker” will play a different line (and subsequently aim at a different area on the lanes) then someone who is what is called a “down & in” player - someone who plays a ball with less hook.

Also, dry conditions (where the lanes have not been oiled recently and the oil carried down and dissapated) obviously will make for more hooking, so the line has to be adjusted accordingly. In addition, WHERE the oil is layed out will mean a different line as well.

Oh, and you don’t EVER aim for the gutter no matter who you are or where you are. You pick a spot on the lanes closee to you - usually one of the first sets of dots - and aim for that.

Why? Well, it’s easier to hit something a few feet away than all the way down by the pins. You then adjust accordingly. Lock in, rinse and repeat!

By the way, my highs are as follows (though I no longer bowl):

Game: 257
3-game series: 672
Average: Somewhere in the 180’s one season

Yer pal,

Looks like you guys have this handled.

Satan, you’re just a piker.
High game: 300, twice.
High Series: 754.
Average: consistenly in the high 190’s.
String of strikes: 18.

Not too bad for a once a week bowler.

One complete set of morals for sale to highest bidder, new in box.

I took Bowling in College for my PE class and they definitely taught the ‘down and in’ technique. The second ball, if you need one, was an even more of a straight shot unless you had a split going. Got an ‘A’ in the class but to be honest don’t remember to much about it. Hey my diminishing brain cells were needed for Macroeconomics.

Tenacious, like a coonhound tracking a poodle in heat.

Good answers. Just want to clarify a few things.

Joey, The angle the ball enters the pin pocket (the area between the 1-3) is more like 15-20 degrees (looks greater from where you’re standing, but I watched it from the other end for 10 years.) Also, just a note, unless you are doing something really unorthodox, you should get better control and lift from using your fingers (w/ or w/o thumb).

DSYoungEsq, The angle is critical. The greatest probability of a strike is (IIRC) ~17 degrees. When graphed, there is a high sharp peak at that angle, low probability outside, and lower, wider peaks further out (greater and lesser angles). There is also a substantial peak on the “brooklyn” side (between 1-2 for RH bowlers).

Satan, Very good point about WHERE the oil is applied. Most people assume it is uniform across the lane. Actually it is heavy in the middle and tapered torard the edges. The ammount of taper, and volume is also varied lengthwise down the lane, and the back 20 feet or so are left dry. This “pattern” can very much affect the performance of the ball. A good “christmas tree” pattern can give scores 20 or more pins greater than a “flat” one.

Funnee, This is still the preferred method for average bowlers. It is much easier to control for changing lane conditions. But it’s hard to get the really high scores consistently.
(and lets face it, to the bowling type, more hook = bigger man ;))

As I said above, I worked in a bowling center (they don’t like to be called “alleys” anymore) for quite a while. So, any other bowling questions?

I don’t buy the notion that spin on the ball is significantly transmitted to the pins and increases pin action. In a collision like this, very little spin will be transferred, and almost certainly not enough to make any difference.

You can try this with billiard balls. If you put extreme english on a cueball, it will transmit some percentage of spin to the ball it contacts, but that ball won’t transfer any measurable spin to a 3rd ball. And a cueball is spinning VERY rapidly compared to a bowling ball, and the spin will hold on the second ball much longer than it would hold on a bowling pin.

I don’t think anyone here implied that. The spin on the ball (about an axis approximately parallel to the lane CL) only causes the ball to hook.

What we are saying is that hitting the pins at an angle (because the ball is hooking) gives more “action”. Instead of being forced straight back, the pins are forced into other pins or into the kickbacks (the walls on the sides of the pindeck) and back into the mix.

Any spinning of the pins is caused by collisions with other pins or the kickbacks once they are in motion. (Actually, spinning pins are usually despised because all that energy went into a spin rather than a lateral movement that might knock down other pins.)

I was responding to this:

It was the second half of this statement I was taking issue with.

The second half of the statement is also true, albeit less true than the part about hitting the pins from the side. You have to remember that your billiard balls are moving over (an almost) two-dimensional plane and transferring not small amounts of their energy to the felt. If you can impart some of the spin from that bowling ball to pins one and two (1&3 for us lefties), you can send that long, skinny, bottom-heavy thing flying and tumbling pretty good as it moves across and back. (Although it sometimes gets to spinning along its lateral axis while sitting on the alley surface without moving across or back, a bad thing as pmh mentioned) It doesn’t have to impart its spin to the other pins, it just has to hit them in funny places, like from behind or high up or whatever. The pin-hit pins will get more action on their own.

Livin’ on Tums, Vitamin E and Rogaine

Manhattan: The billiard balls transfer very little spin energy to the felt. Try this: Use a striped ball as your ‘cue ball’ so you can see the rotation speed, and another striped ball as the object ball. Hit the ‘cue ball’ with extreme side spin so that it contact the other ball directly. The cueball will stop dead, but will be spinning like mad. The second ball will only pick up perhaps 10% of the spin, and probably a lot less than that.

The main reason is that the balls are very hard and fairly smooth, and the collision is inelastic, so there just isn’t a lot of energy transfer other than the momentum of the cueball, which is completely transferred to the object ball.

If you do the experiment with three balls, the third ball will have no spin on it at all (or at least very, very little), no matter what combination of cueball spin and speed you use. And after the collision the cueball will still be spinning like mad, perhaps for 10 seconds.

A bowling ball that is spinning has perhaps 1/100 of the angular velocity of a highly spinning cueball. I just can’t believe that a significant amount of spin would transfer to the pins.

This thread is proof positive bowling can be a thinking person’s game. Too bad the sport of thumbs has gotten so damned expensive you don’t wanna take the kids out on a Saturday afternoon. (I do find the gutter guards provide an interesting billiard-like challenge, though).

Dhanson: I guess I was thinking of backspin on billiard balls, which I don’t often see lasting the length of the table (well, OK, I can’t make it last that long). You’re right of course about the transfer of English from ball to ball and about the non-transfer of “perpendicular” rotational spin to the felt.

On the bowling balls, it only takes a little of transfer. I also want to say that you’d be surprised how much rotational energy is transferred. But first I have to be confident that I’m right. Lot of mass to that bowling ball, and a big outside surface area, but you raise a valid point. Let me spend a few days with a physics book and a bowling ball, and I’ll get back to you.

Livin’ on Tums, Vitamin E and Rogaine

If the billiard pin has a rubber bumper around it, it will pick up more spin. But the ball still won’t transfer all that much, because the rotational inertia of the ball is much greater than the total frictional force between the two objects for the duration of the collision.

I don’t know of an easy way to show this in the case of bowling balls and pins, but it’s easy to see with billiard balls. And if you think about it, billiard balls should transfer more spin between each other than a bowling ball and pin, because the pin is sitting on a flat base that has a lot of friction in the rotational axis, and a billiard ball is sitting on a point and is very easy to spin.

DSYoungEsq wrote:

On every lane I’ve ever bowled, if I released the ball in the direction of the gutter it would enter the gutter long before it ever attained enough friction to begin its curve towards the pins. I tend to have quite a bit of forward velocity. People are always coming up to me and saying they’ve never seen anyone with as much velocity or as dramatic a curve or as much activity in the pocket…
pmh wrote:

Definitely unorthodox. I’ve never seen anyone bowl like I do. I used to use a “finger tip” ball, but found that I was starting to suffer from “Repetitive Strain” type symptoms. I stopped bowling for a while, sold my ball. Then my kids got older and I started bowling again. Alas, most bowling alleys (err… centers) don’t have balls that fit my hands and especially not with a wide enough finger spread to finger tip bowl. So I adopted this ad hoc palming style thinking that I would never be able to get serious with it anyway, due the inevitable wrist pain… but the pain never came, so I’ve stuck with it.

As for spin transferred from the ball to the pins… certainly not in the way that was implied. If you hit a pin dead on, it just gets pushed ahead in front of the ball. If the ball transferred some spin to this pin, you’d never notice. There’s no advantage to a pin spinning about it’s central (vertical) axis. The more oblique the strike the more the pin will pitch to one side and will be more likely to take on a propeller like spin. This is the kind of spin that makes a difference to the other pins.

Also, pmh wrote:

You may be right about them being despised, but personally I think a spinning pin is better. I think of it this way. If a pin hits another pin latterally, it’s more likely that this is the end of the collision chain. If a spinning pin strikes another pin, it’s more likely to place the second pin in a lateral spinning position, making it more likely to strike a third pin and so on.