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Why are Tennis Balls Fuzzy?

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 your 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*

David Frank



  1. Doope Johnson Posted on May 8, 2014 at 7:19 pm


  2. Sportology Posted on June 24, 2014 at 3:21 pm

    Very cool sport-science video! I'm adding this to our playlist on "Great sport science videos on the web" !!! Love it. We should collaborate on something sometime. 

  3. Ayishm Shahzad Posted on July 7, 2014 at 6:21 am

    This is so useful, It's exactly what i was looking for it's perfect for my Physics research 

  4. Steven fenton Posted on May 27, 2018 at 10:24 pm

    They look more Green to me

  5. Yangtze Posted on July 24, 2018 at 12:13 am


  6. Edward Santoro Posted on August 22, 2018 at 11:08 am

    Without the felt, it wouldn't be tennis; it would be racquetball.