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View Full Version : What's a "fast court" or a "slow court"?

BigForehand
02-09-2009, 09:49 PM
I've heard many contradicting opinions on this. What does it mean to be a fast court or a slow court?

What makes a court "fast" or "slow"?

To me, a fast court is one where the ball does not get slowed down in the horizontal direction, so the linear speed is fast, but, the bouce gets absorved very quickly. This makes it bounce a lot of times and very fast. So on a fast court, a ball will travel, say, 80mph across the surface and bounce 3-4 times inside the court before bouncing out.

Slow court for me means the opposite, ball bounces high (easy to return) and the horizontal speed gets reduced on bounce.

What does fast/slow REALLY mean? I've heard all kind of ideas, but how's right? Am I right?

Dilettante
02-09-2009, 10:05 PM
What does fast/slow REALLY mean?

http://www.rago.nl/sesamstraat/~images/grover.jpg

Bottle Rocket
02-10-2009, 08:59 AM
I've heard many contradicting opinions on this. What does it mean to be a fast court or a slow court?

What makes a court "fast" or "slow"?

I'll give a quick response, since I've don't have a whole lot of time, but I wanted to get something out there. I'll check back later and make sure what I said actually makes some sense.

What makes a court surface fast or slow is the friction between the court and the ball. Another less important factor, is the coefficient of restitution (COR) of the court. This is the amount of energy lost because of the softness of the court, energy lost beacuse the court surface "gives". I'll foccus on the friction between the ball and surface, which accounts for most of the differences in court speeds.

One of the most basic principles of physics and engineering is conservation of energy. When a tennis ball is hit, it carries a finite amount of kinetic energy. This is in the form of rotational energy (spin) and translational velocity (pace). Once the ball hits the court, because of the friction between the ball and the court, there is an interaction.

If the court is a high friction surface (grainy, sand, clay, brand new hard courts, maybe rough grass) this makes for a high coefficient of friction between the ball and the court. This decreases the pace on the ball after the bounce, but this energy must go somewhere. It is not totally lost, as energy is conserved. This energy contributes to a higher bounce of the ball instead. This is a slow court.

On the contrary, if the court surface is smooth and fast (old hard courts, smooth courts, carpet, slick grass, etc...), the the coefficient of friction between the ball and the court is much lower. The allows the ball to maintain more of its original pace after the bounce. The trade-off is that the bounce will not be as high. This is a fast court.

Given identical shots, you cannot have both a relatively high bounce and high speed. You cannot have a relatively low bounce and low speed.

Energy is conserved and energy cannot be created nor destroyed.

It must go somewhere. There are obviously other losses caused by many different things, such as wind resistance, balls, humidity, temperature, and the COR of the court surface, but on the most basic level, it all comes down to the roughness of the court.

There are in fact pretty well established methods for testing court surface speed, and it even comes from the ITF! Check below for information and to see the machine used, they even have some videos.

http://www.itftennis.com/technical/research/lab/courts/

Geezer Guy
02-10-2009, 09:51 AM
Pretty impressive BR.

But I gotta wonder... Is there some plageriz'in going on?

Bottle Rocket
02-10-2009, 04:11 PM
"plageriz'in" from where? The ITF website at the bottom of my post?

This is basic stuff (conservation of energy, COR, energy loss, friction, etc...) for a freshman/sophomore level engineering (even civil engineers) or physics student... I don't think my old professors would be too thrilled with me if I coudn't explain something as simple as this.

BigForehand
02-10-2009, 04:24 PM
If there is a high coefficient of friction, this doesn't mean the ball will bounce higher. The velocity in the x-direction will simply be converted to rotational kinetic. If a flat shots hits the ground, it will start spinning because there is a torque on the ball (friction is the force, distance is the radius of the ball).

So you cannot apply the law of conservation of energy here.

Some courts can "give" in when the ball hits it, so it means the ball is doing work on the court meaning that the ball loses energy in the y-direction, making it bounce lower.

But how is grass a fast surface? I would think that the grass blades slow the ball down a ton, so it would put grass on par with clay.

The fastest surface i can think of is ice or polished hardwood. Grass seems slow, and carpet slow too (lots of friction between ball and carpet)

So this is what doesn't make sense....

Bottle Rocket
02-10-2009, 04:57 PM
But how is grass a fast surface? I would think that the grass blades slow the ball down a ton, so it would put grass on par with clay.

The fastest surface i can think of is ice or polished hardwood. Grass seems slow, and carpet slow too (lots of friction between ball and carpet)

So this is what doesn't make sense....

Grass is actually a low friction surface, some grass is more grippy than other grass. The switch they made at Wimbledon a few years ago made it slower, but I don't know much about grass and what kind of grass they had or what they switched to. As far as tennis is concerned, the length of the grass, the type of grass, what is under the grass, how dense the grass is, and the moisture level are all important factors. I'm sure there are others.

I found two coefficient of friction values for the sake of discussion, 0.72 between a car tire and asphalt, and 0.35 between a car tire and asphalt ( http://hypertextbook.com/physics/mechanics/friction/ ). Grass is slick stuff. The carpet they play tennis on is not like the carpet in your home. It is also, in comparion with a hard court and especially clay, is slick stuff.

Polished wood would be fast.

woodrow1029
02-10-2009, 05:09 PM
http://www.rago.nl/sesamstraat/~images/grover.jpg

That is so funny. I laughed a lot when I saw this picture.

Today's thread is brought to you by the letters F-A-I-L

S H O W S T O P P E R !
02-10-2009, 05:10 PM
Let me put this in the simplest terms possible so a noob would understand: fast courts are where the points are faster due to some factor (ie grass, the ball bounces low which makes it easier to win a point if you are underpowered but have good touch and volleys. Your big forehand would be a good weapon, but it wouldn't be super effective on grass.) Slow courts are where the points take longer to end due to some factor (ie clay, the ball bounces high and slow making it easier to retrieve points. You big forehand wouldn't be a major factor on this court either. Then again, I doubt you have a big forehand.)

BigForehand
02-10-2009, 06:03 PM
if you play tennis on hardcourt with a raquetball instead of a tennis ball, would that make the game faster?

By your definition, it would be slower because more friction between ball and surface (raquetballs are rubber, tennis balls have felt, rubber friction >>> felt friction).

And also racquetballs bounce higher, so your definition would say this makes the game slower.

Somehow I feel like playing with a racquetbal is faster. And all these "fail" posters and "noob" posters don't have a clue themselves on what fast/slow means (in tennis terms).

So if you "pros" can provide me with a bullet-proof, working definition, I would like to hear it.

150mph_
02-10-2009, 06:05 PM
racquetball doesnt have air sealed in the ball...
it have very little bounce

Bottle Rocket
02-10-2009, 06:35 PM
And also racquetballs bounce higher, so your definition would say this makes the game slower.

So if you "pros" can provide me with a bullet-proof, working definition, I would like to hear it.

This is actually an important point, that, uhhh, we're talking about tennis balls.

The balls themselves, in fact, may be more significant in many cases than the change in surface. I think the ball change Wimbledon made had a huge impact on the speed of the game.

I would take more time here to try and answer your questions (which would involve doing some more research), but your attitude is annoying, and this seems like a waste at this point - even if your last reponse wasn't directed towards me.

BigForehand
02-10-2009, 06:48 PM
This is actually an important point, that, uhhh, we're talking about tennis balls.

The balls themselves, in fact, may be more significant in many cases than the change in surface. I think the ball change Wimbledon made had a huge impact on the speed of the game.

I would take more time here to try and answer your questions (which would involve doing some more research), but your attitude is annoying, and this seems like a waste at this point - even if your last reponse wasn't directed towards me.

It was directed at the two who called my post "FAIL" and called me "noob" even though this is a legit post.

Doesn't matter if racquetballs don't have air sealed, I'm saying that a higher bounce can lead to faster points. So is high bounce part of slow courts or fast courts?

Bottle Rocket
02-10-2009, 07:39 PM
You were comparing what a racquetball ball does to what a tennis ball does. This makes no sense and doesn't prove anything.

If you take a racquetball ball and play the game of tennis with it on all the surfaces being discussed, the effects depend on the coefficient of friction between the ball and each individual surface - same as a tennis ball. I suspect the order of slow to fast courts would be the same as for the tennis ball, as well.

High bounce is part of slower courts, such as clay.

This is interesting and it depends strongly on the spin on the ball. If you drop a ball straight down onto clay and another straight down onto a hard court, the ball on the hardcourt will bounce higher (saw this mentioned in another thread, but the physics says this is what will happen - all about the COR). If you hit an identical top spin stroke on each surface, I suspect you will find that the ball bounces higher on the clay surface? Uhhh..... I'll have to come back to this some other time... My brain is about to explode.

I just can't stay away from this thread. It just keeps dragging me back in. It might have something to do with its powers of distraction...

Rickson
02-10-2009, 08:23 PM
The bounce isn't necessarily high on slow courts because on red clay the bounce isn't that high, but it is more vertical than horizontal. The ball doesn't zip by you so it appears as though the court is playing slowly. Slow courts suck for net players because the passer almost always has time to get a decent look at a passing shot.

BigForehand
02-10-2009, 09:01 PM
I think the spin affects bounce because the angle it hits the ground. Top spin makes a sharper angle with the ground (closer to pi/2) while a slice will make the ball come in shallow.

The y-vector of velocity is what really counts on the bounce, so sharper angle means more velocity is directed dow*****, meaning more bounce.

But I think that in some cases it will be harder to play with higher bounce, but only if the ball also travels fast horizontally. Imagine trying to reach a ball that's bouncing fast and high... hard to do.

So here is what I have for a "fast" surface, in other words one that will make quicker points:

Low friction, low bounce
Low frictio, high bounce

And here are slow surfaces:

High friction, high bounce.

Thinking about high friction - LOW bounce, i'm not sure if this is a fast surface or slow. Seems like it would be easy to slice/dropshot the ball when the opponent is at the baseline, and they wouldn't make it in time to hit the ball back before 2 bounces. So is high friction - low bounce a fast combo or slow?

TenniseaWilliams
02-11-2009, 08:05 AM
Every court has two speeds, a vertical speed and a horizontal speed.

Vertical speed is mostly the court coefficient of restitution, (COR) a fairly stable ratio of incident ball speed vs rebound speed. There are variations at different angles of incidence, (surprisingly COR goes up for oblique angles) and with exceptions is not effected by ball speed or court friction.

Horizontal speed also depends upon material coefficient of restitution, but is heavily dependent on court coefficient of friction, (COF) and incident angle of the ball. The ITF pace rating is essentially the COF, and does not directly indicate how much the ball will slow when it hits the court.

Grass courts have high horizontal speeds, but lower vertical speeds. Hard courts have widely varying horizontal speeds, but usually have a high vertical speeds. Clay courts generally have a high vertical speed, but low horizontal speed. Two court surfaces can have nearly the same horizontal speeds and produce different shaped bounces from the same incoming ball, due to the ratio of vertical to horizontal speed, and ball spin.

The effects of spin on different court materials varies widely. Clay courts allow material to build up in front of the ball, slowing the ball horizontally and changing the ball rebound angle. Surfaces with lower COF allow the balls to slide longer on the court before bouncing. Balls at very low angles of incidence can bounce before "gripping". Balls with underspin, compounded by large incoming ball speed, can exaggerate the effect. Balls that slide throughout the bounce have measurable less resultant topspin, and much lower vertical COR and horizontal COF.

The speed of the returning shot is generally lower on courts with higher coefficients of friction, which is why the horizontal speed is more generally referred to when overall court speed is mentioned.

peter
02-11-2009, 09:22 AM
Polished wood would be fast.

When I was growing up we had a local indoor city championsship that was playing on just that. And yes, it was insanely fast. It was basically serve. Serve. Serve... And an occasional return of serve winner :-)

mikeler
04-26-2012, 04:49 AM
I'll give a quick response, since I've don't have a whole lot of time, but I wanted to get something out there. I'll check back later and make sure what I said actually makes some sense.

What makes a court surface fast or slow is the friction between the court and the ball. Another less important factor, is the coefficient of restitution (COR) of the court. This is the amount of energy lost because of the softness of the court, energy lost beacuse the court surface "gives". I'll foccus on the friction between the ball and surface, which accounts for most of the differences in court speeds.

One of the most basic principles of physics and engineering is conservation of energy. When a tennis ball is hit, it carries a finite amount of kinetic energy. This is in the form of rotational energy (spin) and translational velocity (pace). Once the ball hits the court, because of the friction between the ball and the court, there is an interaction.

If the court is a high friction surface (grainy, sand, clay, brand new hard courts, maybe rough grass) this makes for a high coefficient of friction between the ball and the court. This decreases the pace on the ball after the bounce, but this energy must go somewhere. It is not totally lost, as energy is conserved. This energy contributes to a higher bounce of the ball instead. This is a slow court.

On the contrary, if the court surface is smooth and fast (old hard courts, smooth courts, carpet, slick grass, etc...), the the coefficient of friction between the ball and the court is much lower. The allows the ball to maintain more of its original pace after the bounce. The trade-off is that the bounce will not be as high. This is a fast court.

Given identical shots, you cannot have both a relatively high bounce and high speed. You cannot have a relatively low bounce and low speed.

Energy is conserved and energy cannot be created nor destroyed.

It must go somewhere. There are obviously other losses caused by many different things, such as wind resistance, balls, humidity, temperature, and the COR of the court surface, but on the most basic level, it all comes down to the roughness of the court.

There are in fact pretty well established methods for testing court surface speed, and it even comes from the ITF! Check below for information and to see the machine used, they even have some videos.

http://www.itftennis.com/technical/research/lab/courts/

I'd hate to see your "long" response!

sphinx780
04-26-2012, 07:47 AM
When I was growing up we had a local indoor city championsship that was playing on just that. And yes, it was insanely fast. It was basically serve. Serve. Serve... And an occasional return of serve winner :-)

I'll go ahead and confirm this, polished wood is very fast. Our college home courts were crossover basketball courts...not full wood, but a polished hard rubber. I've never played anything quicker. Serves and a good slice were deadly.

So, to me a 'slow' court = not polished wood. I like to keep things simple ;-)

Fuji
04-26-2012, 05:16 PM
I'll go ahead and confirm this, polished wood is very fast. Our college home courts were crossover basketball courts...not full wood, but a polished hard rubber. I've never played anything quicker. Serves and a good slice were deadly.

So, to me a 'slow' court = not polished wood. I like to keep things simple ;-)

I'd love to play on a wood court. Sounds like it'd be lots of fun!

I love faster styled hardcourts, I think they are great to hit on. :)

-Fuji

LeeD
04-26-2012, 05:27 PM
Fastest court I've ever played was a grass court in Kahala, Oahu. It had rained for 3 days straight prior to our time, and was soooo slick we couldn't even run without slipping, first serve skidding calf high. It was located right at sea level, about 9' below the street in front.
Slowest was a Q match at the CowPalace, SF, when they first put the second court down (carpet). Most groundies bounced right at my head level, came to almost a complete stop. My shots had no penetration.