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*