Tennis Note #2
Let’s have a conversation about tennis.
As a graduate student with a physics background, I always like to know the back story behind important discoveries and equations. So let us begin with a quick history lesson on tennis.
Great! Now you know why tennis is called tennis. It could be useful on a trivia night at your local bar.
To really get into the basics of tennis, I had my friends ask me a bunch of questions and I am going to do my best to answer all of them. If you have a question, let me know and I will write a sequel to this note.
Why is the scoring system so weird? Where did it originate from?
Well, let’s back up a second for those who do not know the rules of the game. Contrary to belief, it is not a difficult game. In fact the video to the left breaks it down in less than two minutes! Efficient.
Alright, I know the rules of the game, but I still do not understand where this absurd 15, 30, 40 business came from. Why not 15, 30, 45?
Well back in the day, which was a Wednesday, they used a clock’s minute hand to keep score. But remember that win by two business, otherwise known as deuce? Because of that, they decided the scoring would be 15, 30, 40. Then, if both players reach 40–40, the next two points would be 10 each, adding for a total of 60. Make sense?
And where does love come from?
The French, of course! The French word for egg is oeuf (sounds like a French person saying love) and eggs look like zero. Quite obvious. In summary, the tennis scoring system makes total sense.
I heard they change balls every 7 games? Why seven? How did they decide that was the ultimate point of deterioration of the ball?
That is an interesting question that I honestly never thought about. First, let me quote the 2013 grand slam rules. I have quoted the rules because I know you are being lazy about clicking that link. If you do not care about a bunch of jargon, feel free to ignore me for the next minute.
Six (6) balls are to be provided for each Main Draw match and are to be changed after the first seven (7) and thereafter every nine (9) games throughout the tournament. Ball changes and the number of balls used per match shall be the same for all matches throughout the tournament and may be altered only with approval of the Referee in consultation with the Grand Slam Chief of Supervisors.
If a ball is lost or becomes unplayable then another may be added as soon as possible for use in play; when there are fewer than four (4) balls remaining, then another ball must be added for use in play. During the warm-up or within two (2) games after a change of ball, a new ball shall be used as a replacement; otherwise a used ball of like wear shall be supplied. Play must be continuous even if a ball needs to be replaced.
In case of a suspended or postponed match, the balls used in the warm-up will not be the balls used when play resumes.
At least three (3) new balls per day for practice must be available free of charge to each player accepted in the Main Draw or Qualifying competition from the day prior to the commencement of the tournament until he is eliminated. Balls of the make to be used in the Main Draw tournament are to be available for a reasonable period prior to the commencement of the tournament. Players must return practice balls.
Why change at those times? I am guessing it has to do with the rules about the actual ball. Turns out, a tennis ball must pass several tests in this order:
But to really answer your question, I will go straight ahead and quote the ITF (International Tennis Federation):
The effects of nine games of play (i.e. a typical ball change) were established by measuring thousands of new and used balls from tournaments played on a variety of surfaces.
Side note: I now have an insane number of ideas for a senior mechanical lab based course.
Well what happens if a player withdraws from a match? Does the opponent get an automatic win or should the one who lost take his/her place?
If a player withdraws, the opponent gets an automatic win. I do not really have an opinion about if the person who lost previously should take his place. If they had a match between the losers for each round just in case there is a withdrawal, the tournament could last forever. It already is tiresome!
If it is so tiresome, why do the deciding sets not include a tiebreak in the Grand Slams?
Actually, while Australian Open, Wimbledon, and Roland Garros all invoke a rule for the deciding set, the US Open still maintains a tiebreak. In the other three, the player must win by two games. These rules are not set by the ITF but determined by the individual Grand Slams. Technically, had there been a tiebreak at Wimbledon, the longest match in the history of tennis (see note#1) would not have been played. Not to mention the biggest heartbreak I had to sit through in 2009: Wimbledon final. I was cheering for Andy Roddick. Sigh.
Speaking of sets, why are women’s matches best 2 of 3, and men’s 3 of 5?
Technically, only at the slams do men have to play 5 sets. Why is this the case? Honestly, it dates back to when the sport was primarily male dominated. Women were thought of as too weak to play best 3 of 5 sets. Since tennis is a sport of tradition, this is one rule that has not changed. Wonder what they would think if they met Serena Williams back then…
There are a number of articles stating women should play 3 of 5 or men should play 2 of 3. If it means anything, Billie Jean King won 3 sets on Bobby Riggs.
So all these videos above got me thinking, how has racket technology and courts changed over the past 40 years?
Wow. That is a loaded question. Before I get into details, let me introduce the different courts. Currently, tennis features grass, clay, and hard courts, either indoor or outdoor.
Hang on, I watched that video. How exactly does each of the courts affect the speed and bounce?
ESPN Sport Science broke it down for us. Everything always comes back to physics. In fact, if I ever teach dynamics again, I will definitely dedicate questions to the physics of tennis. The ITF takes into account two important properties to determine the speed of a tennis surface: the coefficient of friction and coefficient of restitution. I have plans to really break down the physics but in the meantime, I found this great blog post, explaining it all. The same blog also breaks down the effect of things like temperature, humidity, and altitude on the game of tennis. Alas, another story for another time.
What about my second question about racket technology? Are there any restrictions on racket material that could grip the ball more to effect spin?
Racket technology has certainly changed over time. ITF has certain rules about tennis rackets. The only restriction is on racket size.
As you saw in the first video, rackets were originally made of wood but are now either graphite or aluminum, a much lighter but stiffer material. These materials are easier to maneuver and can handle a lot more vibration as a result.
In order to have a successful racket, the tennis strings must transfer as much energy onto the tennis ball after impact. Tennis players can control material, tension, and gauge. In the tennis world, low tension means more power and high tension means more control. Another hot topic for ‘Tennis Physics’.
Two materials to consider are natural gut or synthetic polyester. Natural gut is made of collagen fiber from a cow’s intestine (insert disgusted emoji). Gut is highly elastic and retains tension much better than polyester, which is stiffer. Therefore, materials will also contribute to this trade-off between power and control. Rod Cross and company did an entire study that is worth checking out! His group also put out another paper on the effects of string tension and racket stiffness on racket performance using beam theory.
We have covered quite a bit but I have a question about challenges? How accurate is hawk-eye technology?
Well first off, for those who do not know, players receive 3 challenges at the beginning of a set. If they challenge a point, and are correct, they keep a challenge. If they guess wrong, they lose a challenge. If the set goes to a tie break, the players receive an additional challenge. If you ask some players, they despise it, mostly stuck in tradition, while others have amazing eyes and are rewarded.
Hawk-eye does 4-D (x,y,z,t) reconstruction of the ball trajectory based on several cameras around the court. Imagine trying to figure out if a ball, like the one in the video, is out. The point of impact would not be clear at the actual speed. We have to slow it down to actually verify. A representative from Hawk-eye explains how the technology works courtesy of the Australian Open.
Alright, enough about physics. I want to know what happened to US tennis? Should we expect to see another dominant force such as the William sisters, Pete Sampras, Andre Agassi, Andy Roddick, etc. in the near future?
Hey now, the William sisters are still at it! Serena is in playing her sixth Aussie Open final this weekend and Venus made the quarter final, only to be defeated by 19 year old American, Madison Keys. The way she played against Venus and then Serena was incredible. The women’s game has plenty of talent. The men’s side for singles tennis is not the greatest but there is some promise. Jack Sock (22) is just breaking ground, but has won plenty of doubles titles for his age. Tim Smyczek pushed Rafa to five sets last week and almost defeated him. The Bryan brothers have 103 doubles titles.
The talent is there, the problem is the game has changed. IBM created two infographics. The first shows how there has been a change in style in order to win Wimbledon. Now this could be because of racket technology and surface changes like we talked about but, I think this is clear at most grand slams. You cannot break serve unless you return well. Granted, if you have poor service you could lose as well. But service is not a problem for American tennis. Take a look at this graphic for American tennis. Most of American tennis focuses on the serve but not the return. Donald Young and Jack Sock, two young talents, may have the highest return games won, but nothing compared to the top ten players. I guess it is better to read an article to about the state of men’s tennis.
The other thing to consider, most American players play college tennis before entering the big leagues. In comparison, Rafael Nadal turned pro at 15 years old and won his first (of nine) Roland Garros titles at the age of 19 years old. What were you doing at 19? I was trying to survive the first year of Cornell Engineering.
These were great questions from my amazing friends. If you guys have more questions, please send them my way and I will try to answer. Until next time, your homework should be to watch the Aussie Open Men’s and Women’s Final this weekend because both should be epic. I would also recommend watching replay of Tomas Berdych v. Andy Murray Semifinal on ESPN3 for pure entertainment purposes or just look at my twitter for an insane number of gifs and vines. Cheers!
P.S. Some academic links above may not be available for non-academics but do not fret, as I said before, I will break down the physics of tennis!
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