Quantcast
nodot nodot
Tennis SET
January 2007 Article

Latest Tennis SET Article

Tennis SET Archive

Send a message to Jani

Tennis Server
HOME PAGE

Do You Want To Be A Better Tennis Player?

Then Sign Up For A Free Subscription to the Tennis Server INTERACTIVE
E-mail Newsletter!

You will join 25,000 other subscribers in receiving news of updates to the Tennis Server along with monthly tennis tips from tennis pro Tom Veneziano that won't be found on the web site.
 
Best of all, it is free!

Player Profiles:
 
Top Pros (Women)
tennis ball Serena Williams
tennis ball Maria Sharapova
tennis ball Petra Kvitova
tennis ball Simona Halep
tennis ball Eugenie Bouchard
tennis ball Agnieszka Radwanska
tennis ball Ana Ivanovic
tennis ball Caroline Wozniacki
tennis ball Na Li
tennis ball Angelique Kerber
 ... more profiles
 
Top Pros (Men)
tennis ball Novak Djokovic
tennis ball Roger Federer
tennis ball Rafael Nadal
tennis ball Stanislas Wawrinka
tennis ball David Ferrer
tennis ball Tomas Berdych
tennis ball Kei Nishikori
tennis ball Marin Cilic
tennis ball Milos Raonic
tennis ball Andy Murray
 ... more profiles
 
Tennis Features Icon TENNIS FEATURES:

BETWEEN THE LINES - Ray Bowers takes an analytical and sometimes controversial look at the ATP/WTA professional tour.
 
PRO TENNIS SHOWCASE - Tennis match reports and photography from around the world.
 
TURBO TENNIS - Ron Waite turbocharges your tennis game with tennis tips, strategic considerations, training and practice regimens, and mental mindsets and exercises.
 
TENNIS ANYONE? - USPTA Pro John Mills' quick player tip.
 
WILD CARDS - Each month a guest column by a new writer.
 
TENNIS SET - Jani Macari Pallis, Ph.D. looks at tennis science, engineering and technology.
 
MORTAL TENNIS - Greg Moran's tennis archive on how regular humans can play better tennis.
 
MENTAL EQUIPMENT - Explore the mental side of the game with Dr. John Murray.
 
TENNIS WARRIOR - Tom Veneziano's Tennis Warrior archive.
 
HARDSCRABBLE SCRAMBLE - USPTA pro Mike Whittington's player tip archive.
 
TENNIS EQUIPMENT TIPS.

Tennis Community Icon TENNIS COMMUNITY:


Tennis Book, DVD, and Video Index
 
Tennis Server Match Reports
 
Editor's Letter
 
Become a Tennis Server Sponsor

Explore The Tennis Net Icon EXPLORE THE TENNIS NET:

Pro Tennis Calendar & Event Links
 
Tennis News and Live Tennis Scores
 
Tennis Links on the Web
 
nodot
Tennis SET
 
Green Dot
 
Tennis Warehouse Logo
 
Green Dot

 
nodot
Court Surfaces - Rebound Ace at the Australian Open

Jani Macari Pallis, 
Ph.D. Photo
Jani Macari Pallis, Ph.D.

Happy New Year Everyone!

With the Australian Open just a few days away, there is tremendous interest in the Number 1 and 2 seeds on the men's side: Roger Federer and Rafael Nadal. Federer dominated the men's game last year with three Grand Slams in 2006 (the US Open, Wimbledon and the Australian Open which he also won in 2004) and runner up to Nadal at Roland Garros. While Nadal had a terrific first half in 2006, the latter part of the last year had some significant disappointments.

The speculation is, of course, who will make it to the finals for the 2007 Australian Open.

There has been a lot of positive speculation regarding Nadal's performance on the Rebound Ace court in Melbourne. Jim Courier, a two time Australian Open champion himself, noted, "Australia suits Rafa's game the best. The surface really accepts his heavy topspin and accentuates it. The ball will have a lot of extra bite, so the conditions there with the heat and the physicality required to play well down there make this an interesting tournament for him."

Bottom line, the Rebound Ace court will provide high bounce and a slower court.

Can a court surface at a particular facility make that much of a difference? (Same court surface but at a different facility.) Lleyton Hewitt believed the 2006 Rebound Ace at Melbourne Park contributed to his elimination in the second round of last year's Australian Open. He noted "unacceptably slow, bouncy and inconsistent Rebound Ace". However, it's recently been publicized that this year's court will have a faster pace and lower bounce.

Temperature also affects the court surface - some players complaining that the court gets 'sticky' (higher friction). So far, the daily high temperature predictions for Melbourne Park are expected to be between 77-82 °F (with the exception of a high next Wednesday of 87 °F). There may be some showers and thunderstorms next weekend.

Tennis courts are made out of a wide variety of materials. Courts are characterized as 'fast' or 'slow' based on the materials and condition of the surface. As the ball hits the court it rolls or skids across the surface. If the ball skids on the court, we say that the court is fast; if it rolls, we say that the court is slow.

You know what that means to your game: grass is fast, clay is slow, hard courts someplace in the middle. On clay courts you have a little extra time to reach the ball. If you've played on the grass court you know you have less time to reach the ball -- you need to prepare earlier. You also know that you're lunging and bending a lot more since the ball doesn't rebound as high on grass.

Aside from your experience, physics tells us that there is a way to quantify court speed. The two parameters key to this are the coefficient of friction and the coefficient of restitution.

Coefficient of Friction (COF)

When two objects slide across one another they both exert a frictional force against one another. These forces are always tangent to the surfaces. A tennis ball and its interaction with the court is an example of this. The frictional force is opposite the direction that the ball is traveling.

The science of physics gives us the following equation: f = mN for objects that slide against one another; where f, the frictional force is equal to N the normal (upward force that the surface exerts on the ball) multiplied by m, the coefficient of friction. m is not a constant; it will vary with the ball and surface type. The more friction there is between the ball and the court the slower the ball will move after the bounce. Balls that skid on the other hand do not generate as much friction and subsequently do not slow down as much after the bounce. So, the COF tells us how fast (or slow) a ball will reach you in the horizontal direction. The higher the COF is for a court the slower the ball will be after the bounce.

Coefficient of Restitution (COR)

For ball/court interaction, the COR is a ratio of the vertical velocity after the bounce to the vertical velocity before the bounce. The COR indicates to us how high the ball will bounce.

Look at these two trajectories. Let's say that both balls have identical velocities coming off the court. We placed little circles on the graph to mark fractions of a second. Each color on each graph designates the period of time. (Red is 0.1 seconds, Blue is 0.2 seconds, etc.). The x-axis (horizontal) represents distance from the bounce. If you are standing 7 feet from the point that the ball bounced, you can see from the graph that the ball bouncing off court 1 is going reach you sooner than the ball from court 2. Part of what has occurred is the horizontal velocity, the velocity component in the direction that the ball travels, is faster for the ball off of court 1 than for court 2.

graph

Velocity has both a magnitude (speed) and direction component.

In trigonometry we learn that the square root of the sum of the squares of sides of a triangle is equal to the hypotenuse. We can apply this same rule to the horizontal and vertical components of velocity: V= (Vx2 + Vy2)1/2; where Vx is the horizontal distance and Vy is the vertical component. So COF deals with Vx and COR deals with Vy. (This is a simplified equation assuming there's no veering off to the side, otherwise you include an additional term Vz.)

Today, a compact measuring device is used which is able to calculate ball size (radius), the angle and ball velocity before and after the bounce, contact time with the surface, and how far the ball slides when in contact with the surface. The Wassing sestie has been used by the International Tennis Federation, Lawn Tennis Association (the governing body for the game of tennis in Great Britain) and the French Tennis Federation.

The International Tennis Federation's Technical website lists the pace of many specific court surface products.

I'm looking forward to seeing how this all pans out next week at the Australian Open.

Green DotGreen DotGreen Dot

Tennis SET Archive

If you have not already signed up to receive our free e-mail newsletter Tennis Server INTERACTIVE, you can sign up here. You will receive notification each month of changes at the Tennis Server and news of new columns posted on our site.

This column is copyrighted by Jani Macari Pallis, Ph.D., all rights reserved.

Dr. Jani Macari Pallis is the founder and CEO of Cislunar Aerospace, Inc., an engineering and research firm in San Francisco. In addition to her engineering practice, she has led two collaborations between NASA and Cislunar, creating educational materials on the aerodynamics of sports for pre-college students and educators. As the head of NASA's "Aerodynamics in Sports" project, she has led a team of researchers investigating the aerodynamics, physics and biomechanics of tennis. The group has conducted high speed video data capture at the US Open and research of ball/court interaction, footwork, serve speeds, trajectories and ball aerodynamics. Pallis received a BS and MS from the Georgia Institute of Technology, an MS in mechanical engineering from the University of California, Berkeley and a Ph.D. in mechanical and aeronautical engineering from the University of California, Davis. She is a member of the Executive Committee of The International Sports Engineering Association.

Questions and comments about these columns can be directed to Jani by using this form.


 

nodot
nodot
Google
Web tennisserver.com
nodot nodot
The Tennis Server
Ticket Exchange

Your Source for tickets to professional tennis & golf events.
 
Barclays ATP World Tour Finals Tennis Tickets 11/7-11/14
 
Davis Cup Finals: France vs Switzerland Tennis Tickets 11/21
 
Chris Evert Pro-Celeb Tennis Classic Tickets 11/22-11/23
 
2015 BNP Paribas Open Tickets Indian Wells 3/11-3/22
 
2015 Miami Open Tennis Tickets 3/23-4/5
 
2015 US Open Tennis Tickets 8/31-9/13
 

 

Tennis MindGame

 
Popular Tennis books:
 
Smart Tennis by John Murray
 
Winning Ugly: Mental Warfare in Tennis-Lessons from a Master by Brad Gilbert, Steve Jamison
 
The Best Tennis of Your Life: 50 Mental Strategies for Fearless Performance by Jeff Greenwald
 
The Inner Game of Tennis by W. Timothy Gallwey
 
Most Recent Articles:
 
October 2014 Wild Cards: Roger Rolls Through 300; Serena Wins First Championship In Cincinnati by Vince Barr.
 
Tennis Warrior: Five Powerful Tennis Concepts by Tom Veneziano.
 
October 2014 Tennis Anyone: Why Can I Not Poach? by John Mills.
 
October 2014 Turbo Tennis: Momentum Revisited by Ron Waite.
 
October 12, 2014 Between The Lines: Home Stretch 2014 -- On the Hard Courts of Asia by Ray Bowers.
 
Tennis Warrior: In Tennis, Principle Trumps Emotion by Tom Veneziano.
 
September 2014 Tennis Anyone: Things To Do and Not To Do by John Mills.
 
September 2014 Turbo Tennis: The Only Thing You Have To Fear Is Fear Itself!!! by Ron Waite.
 
September 9, 2014 Between The Lines: Dissecting U.S. Open 2014 by Ray Bowers.
 
August 2014 Wild Cards: The Tennis Round Table: Interviews With Jim Courier, Todd Martin & Mark Philippoussis in Arizona by Vince Barr.
 

 

 

 

 
 
Featured events in the Tennis Server Ticket Exchanges:
 
  Featured Tickets:
BNP Paribas Open Tickets Indian Wells CA Tennis Garden
Miami Open Tennis Tickets Miami Key Biscayne FL Crandon Park Center
 

  Featured Tickets:
Western & Southern Open Cincinnati Tennis Tickets Session 5 W&SFG Cincy Mason OH Lindner Family Center Financial Group Masters
Western & Southern Open Cincinnati Tennis Tickets Session 6 W&SFG Cincy Mason OH Lindner Family Center Financial Group Masters
Western & Southern Open Cincinnati Tennis Tickets Session 7 W&SFG Cincy Mason OH Lindner Family Center Financial Group Masters
Western & Southern Open Cincinnati Tennis Tickets Session 8 W&SFG Cincy Mason OH Lindner Family Center Financial Group Masters

  Featured Tickets:
US Open Tennis Tickets Men's Quarterfinals Session 21 New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Men's Quarterfinals Session 20 New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Men's Quarterfinals Session 19 New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Session 18 Men's Fourth Round Women's Quarterfinals New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Session 17 Men's Fourth Round Women's Quarterfinals New York City NYC NY Flushing Meadows Corona

  Featured Tickets:
Sony Open Tennis Session 5 Tickets Miami Men's Singles 1st Round Women's Singles 2nd Key Biscayne FL Crandon Park Center
Sony Open Tennis Session 6 Tickets Miami Men's Singles 1st Round Women's Singles 2nd Key Biscayne FL Crandon Park Center
Sony Open Tennis Session 7 Tickets Miami Men's & Women's Singles 2nd Round Key Biscayne FL Crandon Park Center
Sony Open Tennis Session 8 Tickets Miami Men's & Women's Singles 2nd Round Key Biscayne FL Crandon Park Center
Great American Beer Festival Tickets Denver CO Colorado Convention Center

  Featured Tickets:
US Open Tennis Tickets Session 2 Opening Round New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Session 1 Opening Round New York City NYC NY Flushing Meadows Corona
US Open Tennis Tickets Grounds Admission Pass Flushing Meadows Corona New York NY National Tennis Center 8/26-9/9
Arthur Ashe Kids' Day Tickets Flushing Meadows Corona New York NY
Great American Beer Festival Tickets Denver CO Colorado Convention Center

 
 
"Tennis Server" is a registered trademark and "Tennis Server INTERACTIVE" is a trademark of Tennis Server. All original material and graphics on the Tennis Server are copyrighted 1994 - by Tennis Server and its sponsors and contributors. Please do not reproduce without permission.

 

Tennis Server
Cliff Kurtzman
Editor-in-chief
2323 Clear Lake City Boulevard
Suite 180-139
Houston, Texas 77062-8120
Phone: (281) 480-6300
Fax: (281) 480-7715
Online Contact Form
How to support Tennis Server as a Sponsor/Advertiser
Tennis Server Privacy Policy