Open Tennis Serve
oserver
Professional
What does acceleration have to do with ball speed? Racquet head speed should peak just before hitting the ball so acceleration should be zero.
Like several people have already told you, p=mv is the correct formula when dealing with collisions.
The following is from https://en.wikipedia.org/wiki/Momentum
"Relation to force[edit]
If a force F is applied to a particle for a time interval Δt, the momentum of the particle changes by an amount
{\displaystyle \Delta p=F\Delta t\,.}
In differential form, this is Newton's second law; the rate of change of the momentum of a particle is proportional to the force F acting on it,[1]
{\displaystyle F={\frac {dp}{dt}}.}
If the force depends on time, the change in momentum (or impulse J) between times t1 and t2 is
{\displaystyle \Delta p=J=\int _{t_{1}}^{t_{2}}F(t)\,dt\,.}
Impulse is measured in the derived units of the newton second (1 N s = 1 kg m/s) or dyne second (1 dyne s = 1 g m/s)
Under the assumption of constant mass m, it is equivalent to write
{\displaystyle F=m{\frac {dv}{dt}}=ma,}
so the force is equal to mass times acceleration.[1]
Example: A model airplane of 1 kg accelerates from rest to a velocity of 6 m/s due north in 2 s. The net force required to produce this acceleration is 3 newtons due north. The change in momentum is 6 kg m/s. The rate of change of momentum is 3 (kg m/s)/s = 3 N."
oserver
Professional
Haha, why do you join a party?
ChaelAZ
G.O.A.T.
The following is from https://en.wikipedia.org/wiki/Momentum
"Relation to force[edit]
If a force F is applied to a particle for a time interval Δt, the momentum of the particle changes by an amount
{\displaystyle \Delta p=F\Delta t\,.}
In differential form, this is Newton's second law; the rate of change of the momentum of a particle is proportional to the force F acting on it,[1]
{\displaystyle F={\frac {dp}{dt}}.}
If the force depends on time, the change in momentum (or impulse J) between times t1 and t2 is
{\displaystyle \Delta p=J=\int _{t_{1}}^{t_{2}}F(t)\,dt\,.}
Impulse is measured in the derived units of the newton second (1 N s = 1 kg m/s) or dyne second (1 dyne s = 1 g m/s)
Under the assumption of constant mass m, it is equivalent to write
{\displaystyle F=m{\frac {dv}{dt}}=ma,}
so the force is equal to mass times acceleration.[1]
Example: A model airplane of 1 kg accelerates from rest to a velocity of 6 m/s due north in 2 s. The net force required to produce this acceleration is 3 newtons due north. The change in momentum is 6 kg m/s. The rate of change of momentum is 3 (kg m/s)/s = 3 N."
When Bollettieri started his academy he had several course that students had to take on tennis engineering and physics. This reminds me of that format and how they quantified stroke mechanics overall. IMG still requires students to spend at least 25% of there time writing the formulas for their own stroke as part of the BS (Biomechanial Sciences) courses. They break down everything to to scientific components for improvement.
Don't see it much outside the pros and high ranked Junior players though.
Very cool.
Thanks for posting.
oserver
Professional
Haha, so many "experts" are stuck with this continental serve grip, closed serve stance and flex your wrist myths. There is no comparison there among me and them in term of openness, unfortunately.
S
Sirius Black
Guest
Isn't observer right In this regard? If p=mv and p=ft, then mv=ft, and f=mv/t, and v/t=a, so f=ma.
Excuse the lack of deltas
Excuse the lack of deltas
oserver
Professional
"By the time you make contact, the big and SLOW muscles and joints have well and truly done their task." What a complete nonsense!? You mean during the more or less 4 ms ball in contact with the string bed, "big and SLOW muscles and joints have" did nothing to the ball? What a hilarious statement. You need to stop to embarrass your teammates in this debate. You need to read and understand the following -
http://www.popularmechanics.com/adventure/sports/a2072/4221210/
"THE STRIKE
On a 120-mph serve, the ball is in contact with the racquet strings for about 5 milliseconds, moving up to 5 in. laterally across the string plane, gathering spin. The tip of the racquet moves at nearly 120 mph, though at the point of impact, a few inches closer to the ground, the racquet is moving roughly 22 percent slower. The ball's additional speed comes from both the elastic energy in the rubber, which returns 53 to 58 percent of the force exerted upon it, and the racquet strings (strung at an average of 60 pounds of tension), which stretch about 1 in. during the impact."
What it says implies that there are a de-acceleration phase and an acceleration phase during the ball contact of roughly 4 ms. The incoming ball slowdown the racket speed briefly at first (ball getting deeper into the string bed), the the elastic energy stored in the sting bed (body mass and acceleration before the contact point are factors so the racket will not go to negative acceleration toward the back fence). The second phase is the acceleration or re-acceleration phase; "the big and SLOW muscles" all have contributed in this phase.
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oserver
Professional
Thank you! Back to basics is back to physics. In physical analysis, Federer's forehand and backhand models are the modern standard, but unfortunately, his serve model is similar to Agassi's forehand model; it need some modernization using his forehand model.
jm1980
Talk Tennis Guru
I find it hilarious that you have the audacity to call his serve "nothing impressive" when yours is so much worse
This height and weight bullcrap are just poor excuses. There are many women with your build who serve better than you do. Of course they use proper technique instead of trying to serve with a forehand grip
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This. All the physics in the world won't get around the fact that OP serve sucks. Again - why lecture people who are better then you at something? OP not only has a bad serve - its perhaps the worst we have seen posted in TT history..
There was JackB1 with no racquet drop - but I think he got far more zip on it..
Stretchy Man
Professional
The following is from https://en.wikipedia.org/wiki/Momentum
"Relation to force[edit]
If a force F is applied to a particle for a time interval Δt, the momentum of the particle changes by an amount
{\displaystyle \Delta p=F\Delta t\,.}
In differential form, this is Newton's second law; the rate of change of the momentum of a particle is proportional to the force F acting on it,[1]
{\displaystyle F={\frac {dp}{dt}}.}
If the force depends on time, the change in momentum (or impulse J) between times t1 and t2 is
{\displaystyle \Delta p=J=\int _{t_{1}}^{t_{2}}F(t)\,dt\,.}
Impulse is measured in the derived units of the newton second (1 N s = 1 kg m/s) or dyne second (1 dyne s = 1 g m/s)
Under the assumption of constant mass m, it is equivalent to write
{\displaystyle F=m{\frac {dv}{dt}}=ma,}
so the force is equal to mass times acceleration.[1]
Example: A model airplane of 1 kg accelerates from rest to a velocity of 6 m/s due north in 2 s. The net force required to produce this acceleration is 3 newtons due north. The change in momentum is 6 kg m/s. The rate of change of momentum is 3 (kg m/s)/s = 3 N."
You didn't answer my question. What does acceleration have to do with ball speed?
oserver
Professional
"Again - why lecture people who are better then you at something?" Remember, I hold a coach certificate. Many coaches lecture their students who are way higher in playing abilities, include all elite player's coaches; what's wrong with that? According to your logic, only Federer can coach at this moment, nobody else, and if Nadal take over the #1 spot, only Nadal can coach the entire world, no one else including Federer.
Think about what your are going to write before you write and publish it!
oserver
Professional
Simple - ball goes back because there is a F(orce) exerted on it. The F(orce) = M(ass) times A(cceleration). So the Force is proportional to both Mass (body plus racket) and acceleration (of the racket). On the ball side, with the ball mass being constant, the big the Force, the higher the ball speed.
jm1980
Talk Tennis Guru
This is such bad physics. By this logic, a huge obese man can get immense acceleration swinging the racquet with the same acceleration as an athletic person half their weight
Topspin Shot
Legend
I think you're being serious? Newton's laws are mathematical models, which means you have to apply them correctly and substitution doesn't always work. F=ma is used to see how much steady force you need to acclerate an object. P=mv is for collisions.
Topspin Shot
Legend
Stretchy Man
Professional
Acceleration will be close to zero at time of impact so force will also be zero according to your formula. How do you explain this?
A
Attila_the_gorilla
Guest
See this is your main problem. You cannot communicate. You are either unable to pay attention to detail, or you try to misunderstand things on purpose, hoping to twist words in a way that fits your childish agenda.
The big and slow muscles, eg your legs, trunk, your shoulder, are all inactive by the time you make contact. That is the definition of a whip, or a kinetic chain. When you make contact, your legs are (should be) in the air. Your abs have already pushed you up, your trunk has already turned to face the court, your shoulder has already executed the external and most of the internal rotation. The only active part is the end of the whip, ie the hand. Which happens to be the most flexible and quickest.
What you're talking about is how string displacement contributes to ball speed. Absolutely irrelevant to this topic, and again is just a sign of your inability to communicate.
But if you're desperate to talk about strings and how long the ball stays on the strings, I have bad news for you. Ball speed is not a function of "dwell time". It's about string displacement. In a faster swing (ie faster racket head speed), the strings get displaced further, but it happens quickly.
In a slow swing, the string don't get displaced so much, but it happens slower.
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Attila_the_gorilla
Guest
He's hopeless
S
Sirius Black
Guest
I just have a basic knowledge of physics, but isn't m delta v = f delta t used to in collision problems? As in, an object with a certain amount of momentum will not experience as much force in a collision if the time it takes for them to come to a stop is increased?
And isn't that just derived from f=ma?
A
Attila_the_gorilla
Guest
Whatever happened to good old fashioned common sense...
Topspin Shot
Legend
Yes mdv = fdt is used the way you describe it. While it's dimensionally equivalent to f = ma, I don't like the word derived because it implies you can make all sorts of claims about the physical world just by playing with the algebra. Getting the physical laws right is what's important, not the math in the models.
Went out the window with open 360 and Pomo.
Sent from my SM-G955U using Tapatalk
oserver
Professional
Your are wrong again. An athletic person has muscle strength advantage to accelerate the racket much faster than a huge obese man. Beside, to hit the ball well you need to have trained skills (such as just using wrist/arm to swing the racket versus good coordination between large muscle groups and smaller ones); apparently the huge man unlikely to have.
jm1980
Talk Tennis Guru
No. In a tennis serve you should be gripping the racquet very loosely. Because of that, a negligible amount of the player's own mass exerts force on the ball. Weight should hardly be a factor.
Also, you are the one constantly bringing up height and weight "advantages" when technique is significantly more important, specially for someone your level
Go play a decent 14-year-old junior who is likely going to be both shorter and lighter than you, and see how that works out for you
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SinjinCooper
Hall of Fame
Trolling replaced it, sometime around Internet A.D.
oserver
Professional
"In a tennis serve you should be gripping the racquet very loosely." Completely agree with you in this regard. How can you gripping the racquet very loosely? The only way is to let your grip in the extension state (or close to extension state), just like Federer's forehand. If you flex your wrist, the grip is automatically tightened; you just cannot help it. The current serve model uses a relatively tight grip, but I serve use a loose grip now, plus a passive arm just like Federer's forehand.
BTW, I played trained juniors many times in adult/junior tournaments, most time I won. The most recent was the Memorial Day in May in a club tournament. I paired with a 12 year old boy to beat four other pairs to win the tournament.
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meltphace 6
Hall of Fame
Bunch of masochists.
oserver
Professional
OMG, "masochists", you made a pretty remote connections. Who will you include beside the originator?
A
Attila_the_gorilla
Guest
You can't communicate!!!
You ("the originator") are not one of the masochists. The masochists are your victims that give this pathetic thread our time and energy.
You are a sadist for exposing us to your painful ideas.
oserver
Professional
See below
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oserver
Professional
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Attila_the_gorilla
Guest
The real issue is that you can't communicate, you haven't got a clue, and even worse, you seem to have unwavering conviction about your braindead ideas.
oserver
Professional
The real issue is that you guy can't focus. Give me a focused serve form or technique idea to argue, then start to argue on the point. Don't copy the open 360 rookie guy who can only repeat the "open 360" in one sentence without statements or arguments.
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BlueB
Legend
Oh great, we are going to be introduced to a new Focused Serve Technique (c), very soon! FoSTec (c), bring it on!
Sent from my SM-G930W8 using Tapatalk
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Attila_the_gorilla
Guest
Your ideas have been ripped to sheds methodically and with great focus. Saveme the trouble of quoting my previous posts that have demonstrated with sound arguments why your ideas are nonsense. Your Open serve was proven to be lunacy, then you moved on to wtist extension. It has been demonstrated multiple times why you cannot apply forehand technique to the serve, but you keep parroting the same rubbish.
Now your wrist extension serve has also been debunked, the air is filled with anticipation about your next revolutionary concept. Serving with a two handed backhand?
oserver
Professional
"Your Open serve was proven to be lunacy, then you moved on to wrist extension." You got the later half right, first, I opened stances, then, grips, but still using the closed stance/closed grip techniques. I got some progresses there on forms along without new techniques. Than, by carefully analyze Federer's forehand techniques in comparison to Agassi's, the holy grail came out. That is the wrist extension serves. Nothing new, so to speak if disregard type of strokes. The only thing new was that the forehand techniques were used for serves, not limited to forehand.
Regarding the "anticipation about your next revolutionary concept", I don't have any. But, just the open serve forms and wrist
extension techniques can take a long time to be adapted. Remember, sport things change impatiently slowly. The continental serve grip lasted more than a century now and is still going strong. How do you punch a whole in a well adapted tradition overnight? You cannot. Meanwhile, I just serve with a very relaxed wrist and a passive arm, and answer questions like - "what kind of serve is this?" to satisfy players who have curiosity and ability to spot something new.
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Stretchy Man
Professional
Now you're saying there is no racquet acceleration or negative acceleration. You're all over the place.
I seriously can't not believe you are still at this. Yeah sure technically you do not have to be better at something to teach people about it. But its rare that people are BAD at it. i wouldn't learn music from a guy who is tone deaf. Wouldn't let a blind person teach me to drive etc.
Federer as you point out has coaches who are not as good as him - but they are former pros - like Edberg - who once served quite well!
Your serve is TERRIBLE. Maybe by some miracle you can went 2-1 at 4.0 3 years ago.. But your serve still stinks. So your serve is terrible - it has always been terrible and no person with a good serve on this planet uses your technique!
Now Yandell's serve might not be great (though i'd wager its better then yours) but at least his clients can serve well using his techniques! You live in a fantasy world. The only people using your ****ty technique are 2.5 - 4.0 pancake serves who serves are their weakness. The rest of the world tries to copy pro technique. You just live in a fantasy world and imagine your ****ty technique is better..
Somehow you try to turn the idea that absence of proof that your technique sucks (other then the fact that no one uses it - LOL) is proof that it really works great. This is beyond comical - its almost sad.
It's like Tosh.O is going to make a documentary about you.
Topspin Shot
Legend
Sadly people fall for this sort of quackery all the time. Oserver, bssh and the other TT clowns are so antisocial and comically inept nobody falls for them, but a guy with people skills can do some real damage.
chunlimeyers
Rookie
Wow, I can't believe this thread is still going on!(I read this like a month or TWO AGO and figured it would fizzle out after enough razzing and science proving him utterly wrong!)... The male ego to REFUSE to admit that this open serve SUCKS cannot be stopped, only held on in moronic infamy on this wayyy too long TT thread! Oh man this guy must be more bored than ME right now! HAHA!!
oserver
Professional
"after enough razzing and science proving him utterly wrong!" by who, or which post(s)/posters) have enough science to prove me wrong? Have you tried wrist extension serves? Do you know anybody who proved me wrong have ever tried it? Name it and show some videos, can you? How do you know I was wrong if no one had hands on experiences? Science need experiments, no way to get around it. Where is your experiments?
oserver
Professional
How many posts you devoted on my USPTA certificate issue on this thread and others. How many dubious "knowledge" physics you like to teach here to waste viewer's time? More to come?
oserver
Professional
Sorry, not me, but eventually I'll be there. You too.
heninfan99
Talk Tennis Guru
This reminds me of the spry fellow that claimed to have invented a new type of two handed backhand a few years back.
oserver
Professional
So you know someone taught this type of wrist extension serves? Can you point some videos or lectures. I'm ok to take a backseat in this heated debate.
Doctors whose therapy is unusual and don't cure anyone are quacks. Tennis players/coaches who can't serve well - and whose unusual methods haven't allowed anyone to serve well are..
Well quacks seems like a very good word choice - don't you think?!
It's a strange thing to be a quack on - but I guess the internet brings out a lot of weirdos.
Why don't you write Jeff Salzenstein and tell him he is 'wrong' with how he serves. LMAO. I have seen him advocating for a MORE closed stance..
I love to see a 'serve' contest between you and Salz..
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