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  • If you've ever watched tennis, or you've ever played it, you may have wondered why is the

  • tennis ball fuzzy?

  • Why are tennis balls fuzzy?

  • So why are tennis balls fuzzy? No ones really asked me that question.

  • Alright, cause I got to ask you the same question I asked everybody else: Why are tennis balls

  • fuzzy? Its to slow them down

  • Tennis balls are fuzzy cause it cuts down on the aerodynamics of the ball

  • It slows down the wind resistance.

  • Its almost kind of like the fuzz slows the ball down. The fuzz slows the ball down? Yeah,

  • it slows it

  • You know, today's times since the rackets and the strings have become more powerful,

  • they put a heavier felt on the ball to kind of slow things down.

  • See the fuzziness makes it so they don't go through the air quite so fast, otherwise even

  • the world's best players wouldn't be able to return a serve or something like that.

  • So one thing that everybody that I talked to said was that fuzz on a tennis ball was

  • to slow it down. See when a tennis ball hits a racket, it creates a lot of momentum, and

  • an otherwise smooth ball would go really fast. But its not just about speed, there's more

  • to it than that. Its about control.

  • The tennis ball's being fuzzy how you control the speed. Cause they're easier to bounce

  • off of, its easier to make them bounce. It also gives you more control over spin and

  • things of that nature. With the fuzz it definitely, like, you can control the ball a lot more.

  • So speed and control. But there's more to it than that when it comes to the fuzz on

  • a tennis ball.Its a little bit of history and its a little bit of physics. So I went

  • to the University of Tulsa to hang out with the tennis team and the physics department

  • to find out the physics to the fuzz.

  • I think first of all its fuzzy because just the origins of tennis. Back in the 16th and

  • 17th century when court tennis was first getting started they would cover cork with cloth and

  • wool and hair and you don't want to mess with tradition so its maintain the fuzz even to

  • today. But there's several performance reasons why you would prefer fuzz on the ball.For

  • instance, top athletes can hit the ball over 150 miles an hour on a service, and on a forehand

  • they might hit it 70 to 80 miles and hour. That coming so quickly, its almost at the

  • edge of athletes ability to react to it. And so the hair actually can slow down the ball.

  • It increases the drag much in the same way that barnacles on ship will slow the ship

  • down, and so every good yachtsman knows that if you want to speed up a ship you get the

  • barnacles off the hull. In the same way, the fuzz will slow down the ball. Another thing

  • too is that the fuzz will increase the effective spin. Tennis is a game of putting spin on

  • the ball. That's due to a force called the Magnus effect.

  • The Magnus effect, or Magnus force was named after German physicist H.G. Magnus. See when

  • a tennis ball spins, the fuzz on the ball catches air particles and it creates a boundary

  • layer around the ball.

  • Anytime a ball is rotating in an air stream, it kicks some of the air upward, and there's

  • a basic law of physics that says if that's going to happen then the ball's going to have

  • to move downward to compensate. So a tennis player that puts top spin on the ball, the

  • ball will move down as a result. Or if they put backspin it will tend to float, hang up

  • in the air a little bit longer. So the presence of the fuzz will increase the effect of spin.

  • But really the only way you're going to know for sure is to actually get a tennis ball

  • that doesn't have any fuzz on it.So I took a ball out of the same can as this one and

  • with a belt sander just shaved off all the hair and then let tennis players play with

  • it.

  • Well, playing with the rubber ball, which has no fuzz on it, the ball bounces a lot

  • more. So, if you put any amount of spin, the ball's going to bounce way higher than when

  • the ball's fuzzy. So that makes it a lot harder to play. Also without the fuzz, the ball's

  • smaller in size and lighter, so when it's lighter it has a tendency to fly easily, like,

  • you hit a ball and even if you hit it a little harder than usual its just going to fly off

  • the tennis court. And hit the ceiling? Yeah, hit the ceiling, hit the fence, hit people,

  • I don't know.

  • Now one of the first things you notice is that it's much bouncier, harder to see, and

  • when you play with it, it's harder to adjust to it, harder to pick it up, harder to get

  • it to spin the way you want.

  • Did you like the not-fuzz? Was it fun? Was it just frustrating cause it was hard to control?

  • It was just different.I wouldn't say it was more fun or anything. It wasn't comfortable

  • though.It's not comfortable, no. No it wasn't comfortable.I would hate playing with the

  • ball which had no fuzz on it. It would be horrible.

  • Now when it comes to tennis, there's more factors about controlling a ball than just

  • spin. There's different kinds of tennis courts. There's hard tennis courts like this one,

  • there's clay courts, and there's grass courts, and a tennis ball will react differently depending

  • on the kind of court that you're on. So players have to adjust on how they control the ball,

  • depending on where they play.

  • So there's a number of performance reasons.For instance, I didn't realize that tennis balls

  • come with different size fuzz on it, depending on what altitude you're going to play at. If

  • you're playing at a high altitude, then you need more fuzz on the ball to slow it down

  • through that thinner air.

  • So that's some of the physics of why tennis balls are fuzzy, but why the yellow color?

  • Probably some horrifying experiment in the 1960's I would imagine. Otherwise I don't

  • know.

  • Why yellow? Cause it picks it up, its much easier to pick it up.

  • In the color spectrum, yellow is the easiest color for the human eye to see, and certain

  • shades of yellow are so luminous that we can see them even in dark situations.

  • And this is also the reason why a lot of modern day tennis courts are dark. It's to contrast

  • that yellow ball and to make it more visible and easier to follow.

  • But it hasn't always been that way. See before the 1960's and 70's, tennis balls were either

  • white or black, depending on the what kind of court you were playing on.But with the

  • development of color cameras and broadcasting and recording these tennis events, they realized

  • that yellow is the more visible color that can be picked up by these cameras. So in 1972,

  • the first yellow tennis ball was introduced, and we've been playing with them ever since.

  • So there's a number of performance reasons why you want fuzz on a tennis ball, but ultimately

  • it goes back to that's the way they've always done it. Tradition? Yeah.

  • If you want to see another video about the Magnus effect, go check out Veritasium's video

  • here.

  • So the next time you're playing tennis and you look at a ball, and wonder why it's fuzzy.

  • Now you know why.

  • So the first question is why are tennis balls fuzzy, with a helicopter noise in the background.

  • Well, tennis balls are fuzzy *laugh*

If you've ever watched tennis, or you've ever played it, you may have wondered why is the

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Why are Tennis Balls Fuzzy?

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    Brandon posted on 2015/01/29
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