Why do bowlers curve the ball?

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It looks cool and it seems like everyone who is actually good at bowling will make the ball spin and curve.. My question is why?

Again, I’m not good at bowling but why aren’t people just smashing it in the middle? If you’re gonna dedicate countless of hours to practicing, why not master the most consistent type of throw? Is there some physics aspect that makes the pins go down easier when hit by a ball that has a sideway rotation

In: Physics

7 Answers

Anonymous 0 Comments

As others have pointed out, trying to roll the ball straight down the middle will tend to clear the middle pins but leave the outer pins on both sides standing. So not only does that stop you throwing a strike, but it also makes it almost impossible to clear the remaining pins with your one remaining throw, to hit a spare. You could throw straight and more to the side, but that will tend to only clear one side, with zero chance of a strike.

To throw a strike, what you want is to hit somewhere between the pin that is at the tip of the triangle, and the pin next to it, either to the left or the right. Let’s assume you pick slightly right of center. You then want the ball to be coming in diagonally from that point, cutting leftwards across the triangle rather than going parallel to the bowling lane. But how do you do this? There is no straight line from where you throw the ball that lets it cut diagonally across the pins. You’d have to “steer” the ball around a bend somehow, so that it can approach in one direction, and then hit the pins in another direction.

This is where spin comes in, but there’s a crucial element that other answers have left out (or else I’ve missed it): the surface that the ball rolls on is **oiled**, which makes it slippery. And this oil isn’t applied evenly across the lane. There is more oil at the beginning than at the end. This means that, just after you release it, the ball tends to slide across the surface more than roll, and so its spin doesn’t impact the ball’s trajectory at this stage. It just slides in the direction that you released it in. But then, usually about 2/3 or 3/4 of the way along the lane, the oil cuts out and the ball experiences a lot more friction with the ground, which means that its spin now starts to impart a force, and thus steers the ball in a different direction. And that’s how you can get a bowling ball to go around a curved trajectory.

An important part of high-level bowling is that different lanes have different oil patterns, either by design or due to wear from usage. So a good bowler has to understand the oil pattern they are dealing with, and how to adjust their throw.

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