Federer-the greatest pusher of all time !!!

Gregory Diamond

Professional
I'll put it once, in casual manner to stay within messageboard format. If you need deeper dive into strict description, I'll leave that to you.

1. Your force formula is for force applied to an object. Consider ball mass and ball acceleration to use it. If you want a formula for racquet-ball interaction, it's energy transfer and E=mc^2. However, in a simple application it doesn't take into account object shapes, elasticity, etc, which are a part of equation for actual physics of tennis stroke. If you had a steel sphere hitting a tennis ball directly center-towards-center, you could more or less consider that sphere mass and approach velocity to calculate E. And compare those of different spheres moving with different velocities.

2. For rotational motions it's the relation between "distance of contact point to pivot point" and "distance of mass location to pivot point" which determines the mass "piece" contribution to the interaction energy. Think baseball bat: hit the ball conventional, or flip the bat upside-down and hit the ball with the handle. Moreover, distance is squared for this equation. Which makes mass located around the contact significantly more contributing. You asked about cutting the racquet - yes, a racquet with lighter handle, but same mass in the hoop, will deliver nearly same power for the hit. So even if we you somehow managed to ensure non-elastic wrist, contribution of arm mass would be diminishing with the distance, significantly.

3. You just cannot ensure the wrist to be firm enough to create a monolith arm-racquet structure. Check it - "lock" your wrist as hard as you can with a racquet and make someone throw a ball onto it. It will give way due to joints and muscle elasticity and inconsistent nature of muscle deformation - muscle fibers are never truly static. Now, there'd be some point of limit for the wrist extra lay-back under pressure of collision with incoming ball, but the ball would be gone by that moment. If 3-4ms figure tells you nothing, whatch slow-mo of shanks by pro-players: even though the racquet twists badly, the ball departs with almost the same direction as for sweetspot hit. All visual twisting happens later. Same for the wrist - it still absorbs the collision, tendons stretching, while the ball is already gone. No "feel of entire body", or even arm, through contact.

4. Once again to the "even if we you somehow managed to ensure non-elastic wrist", there's an arm pivoting at shoulder joint before, during and after contact, which separates it from the torso. Actually, if you want entire body mass to contribute to the contact, you should grip the racquet head with both arms at 9 and 3 o'clock and place it facing the incoming ball at belly level, arms bent 90 deg and elbows fixed against pelvis bones. This would arguably eliminate most elastic joints.

5. Even for linear motions, like straight punch in karate, E=mc^2 works for the fastest moving part. The mass of forearm. The velocity of forearm. All body contributes to the punch with proper technic, but its via building up the speed - either via kinetic chain transfer, or via compound, simultaneous activation. This might be a tad simplified, as joints are not exactly hinges, but still a decent model. While actual physics of tennis strokes still hasn't been fully described and modeled, neither the swingpath, nor the sringbed-ball collision. To many moving parts, biomechanical power sources and elastic interactions.

Disclaimer: I'm sorry for all the impresise terms, being neither English native speaker, nor having studied physics in English. Still tried to cover key ideas in a popular manner.
You are wrong. I`ll give you the best explanation. Imagine we placed the racket vertically on the table(without connecting the handle with the table) and directed fast ball towards the strings. The ball will bounce off the strings(if the speed of the ball is not too great) and the racket fall in the opposite direction. Now we repeat the same but we connect the handle firmly with the table. Ball with the same initial speed will bounce back with much greater speed. There is no doubt. The racket at the end will be in the same place. Racket absorbed the kinetic energy of the ball and gave it back to the ball(not all but a large part of it). In the first example a great part of energy the racket obtained from the ball was wasted. This energy caused the racket to fall back. If we observed what happens during the collision of the ball with the racket in a real stroke but we did it from the point of view of observer moving forward with the speed of the handle we would see the same difference between reaction of the ball and the racket after the stroke. It is easy to explain. The time the ball touches the strings is not the same. It may be short but it differs significantly. Change of momentum = force x time. This formula can be derived from Newton`s rules. It all means that if you want to obtain the same change of momentum of the ball throwing racket at the ball you should do it with much greater speed what has to cause loss of control.

So you can ask what is the best solution. You just have to accelerate the racket(speed of the racket is important factor) but you cant surpass the speed when you cant keep the right wrist laid back.You should be near that point but you cant accelerate the racket more because you will lose control. You can be sure that your results will be the best if you play that way.
 
Last edited:

J011yroger

Talk Tennis Guru
I'll put it once, in casual manner to stay within messageboard format. If you need deeper dive into strict description, I'll leave that to you.

1. Your force formula is for force applied to an object. Consider ball mass and ball acceleration to use it. If you want a formula for racquet-ball interaction, it's energy transfer and E=mc^2. However, in a simple application it doesn't take into account object shapes, elasticity, etc, which are a part of equation for actual physics of tennis stroke. If you had a steel sphere hitting a tennis ball directly center-towards-center, you could more or less consider that sphere mass and approach velocity to calculate E. And compare those of different spheres moving with different velocities.

2. For rotational motions it's the relation between "distance of contact point to pivot point" and "distance of mass location to pivot point" which determines the mass "piece" contribution to the interaction energy. Think baseball bat: hit the ball conventional, or flip the bat upside-down and hit the ball with the handle. Moreover, distance is squared for this equation. Which makes mass located around the contact significantly more contributing. You asked about cutting the racquet - yes, a racquet with lighter handle, but same mass in the hoop, will deliver nearly same power for the hit. So even if we you somehow managed to ensure non-elastic wrist, contribution of arm mass would be diminishing with the distance, significantly.

3. You just cannot ensure the wrist to be firm enough to create a monolith arm-racquet structure. Check it - "lock" your wrist as hard as you can with a racquet and make someone throw a ball onto it. It will give way due to joints and muscle elasticity and inconsistent nature of muscle deformation - muscle fibers are never truly static. Now, there'd be some point of limit for the wrist extra lay-back under pressure of collision with incoming ball, but the ball would be gone by that moment. If 3-4ms figure tells you nothing, whatch slow-mo of shanks by pro-players: even though the racquet twists badly, the ball departs with almost the same direction as for sweetspot hit. All visual twisting happens later. Same for the wrist - it still absorbs the collision, tendons stretching, while the ball is already gone. No "feel of entire body", or even arm, through contact.

4. Once again to the "even if we you somehow managed to ensure non-elastic wrist", there's an arm pivoting at shoulder joint before, during and after contact, which separates it from the torso. Actually, if you want entire body mass to contribute to the contact, you should grip the racquet head with both arms at 9 and 3 o'clock and place it facing the incoming ball at belly level, arms bent 90 deg and elbows fixed against pelvis bones. This would arguably eliminate most elastic joints.

5. Even for linear motions, like straight punch in karate, E=mc^2 works for the fastest moving part. The mass of forearm. The velocity of forearm. All body contributes to the punch with proper technic, but its via building up the speed - either via kinetic chain transfer, or via compound, simultaneous activation. This might be a tad simplified, as joints are not exactly hinges, but still a decent model. While actual physics of tennis strokes still hasn't been fully described and modeled, neither the swingpath, nor the sringbed-ball collision. To many moving parts, biomechanical power sources and elastic interactions.

Disclaimer: I'm sorry for all the impresise terms, being neither English native speaker, nor having studied physics in English. Still tried to cover key ideas in a popular manner.

E=mC^2 has absolutely nothing to do with a tennis racquet hitting a ball.

J
 

a12345

Professional
"If we push on an object in the forward direction while the object is moving forward, we do positive work on the object. The object accelerates, because we are pushing on it. F = ma. It gains kinetic energy. The translational kinetic energy of an object with mass m, whose center of mass is moving with speed v is K = ½mv2.

Translational kinetic energy = ½ mass * speed2

Kinetic energy increases quadratically with speed. When the speed of a car doubles, its energy increases by a factor of four.
A rotating object also has kinetic energy. When an object is rotating about its center of mass, its rotational kinetic energy is K = ½Iω2.

Rotational kinetic energy = ½ moment of inertia * (angular speed)2.
"

Ive taken this text from a Physics website and I look at it like this.

The kinetic energy of transferring energy from a ball hitting another ball is proportional to the speed and mass of both balls. A heavier ball moving at speed V will transfer more energy than a lighter ball moving at speed V, to another object.

The Rotational Kinetic energy merely swaps the variable "mass" with "moment of inertia", which itself is related to mass but calculated differently.

Moment of inertia is the product of the mass and the square of the distance from the pivot point:

Moment of Inertia = mx2 (m=mass x= distance from the pivot point)

(The total moment of inertia for a bat would be calculated by imagining cutting the bat into tiny pieces all connected to each other and weighing those pieces ,with the mass at the end of the bat having more effect.)

The Moment of inertia for swinging a racket or a bat is the mass of the bat but also the mass of your arm and body around the pivot point (lets say the pivot point is the centre of the top of your head). So your body weight adds to the moment of inertia.

So either way if its a transfer of translational kinetic energy or rotational Kinetic energy, the mass of you body and your arm, connected to the racket or a bat, has an effect on the amount of kinetic energy transferred.
 
Last edited:

Gregory Diamond

Professional
If we place a spring between two metal balls and compress it then after releasing the balls they will gain kinetic energy. Ratio of the energies gained by these two balls is inversely proportional to their mass. It means that the ball with the smaller mass gains more potential energy of the spring. So if the real tennis ball interacts only with accelerated racket head then a lot of energy is taken by the racket. It is wasted. If the ball "feels" the whole body (because of laid back wrist during collision) then most of the energy is transfered to the ball. Using the second method you dont need to accelerate the racket so fast to accelerate the ball. You have greater control. You win tournaments because you play where you want.
 

J011yroger

Talk Tennis Guru
If we place a spring between two metal balls and compress it then after releasing the balls they will gain kinetic energy. Ratio of the energies gained by these two balls is inversely proportional to their mass. It means that the ball with the smaller mass gains more potential energy of the spring. So if the real tennis ball interacts only with accelerated racket head then a lot of energy is taken by the racket. It is wasted. If the ball "feels" the whole body (because of laid back wrist during collision) then most of the energy is transfered to the ball. Using the second method you dont need to accelerate the racket so fast to accelerate the ball. You have greater control. You win tournaments because you play where you want.

No.

J
 

Gregory Diamond

Professional
Which part dont you understand ? The part with the spring is just obvious. Potential energy of the spring is transfered as a kinetic energy to the balls. Initial momentum is equal 0 so direction of momentum of two balls have to be opposite and equal in value (principle of momentum conservation ). If you add principle of energy conservation in elastic collisions after simple calculation you can get the answer.
 
Last edited:

J011yroger

Talk Tennis Guru
Which part dont you understand ? The part with the spring is just obvious. Potential energy of the spring is transfered as a kinetic energy to the balls. Initial momentum is equal 0 so direction of momentum of two balls have to opposite and equal in value (principle of momentum conservation ). If you add principle of energy conservation in elastic collisions after simple calculation you can get the answer.

I understand just fine.

You are very wrong.

J
 

J011yroger

Talk Tennis Guru
But F=ma does.
Graphene_structure.svg_.png


J
 

West Coast Ace

G.O.A.T.
My god where do these crazy people come from..
Inbreeding is one obvious possibility. Licking lead paint as a baby....

Comedy gold. Fed the pusher..... guy has over 1200 matches; probably averaged ~40 winners per match.... yeah, pushing wins on the ATP tour
 

jch

Rookie
I will make a thread about inertial tennis, to give a source of knowledge for interested players. Then admins will remove all links and it will be useless. Not my problem.

They found a better solution.

I tried.

You decided.
 

oserver

Professional
We are wasting time talking about one handed forehand but we all know that two handed forehand is the future of tennis.

"we all know that two handed forehand is the future of tennis.", am I outdated? Just like not belonging to "all" in the 3C serve forms/techniques, I don't know two handed forehand would be "the future of tennis". Adding another arm just for depriving the power of large muscle groups below the shoulder?

Federer already diminished the power of his right arm to a minimum by using a passive arm. So what's the benefit of adding another active arm for?
 

Gregory Diamond

Professional
"we all know that two handed forehand is the future of tennis.", am I outdated? Just like not belonging to "all" in the 3C serve forms/techniques, I don't know two handed forehand would be "the future of tennis". Adding another arm just for depriving the power of large muscle groups below the shoulder?

Federer already diminished the power of his right arm to a minimum by using a passive arm. So what's the benefit of adding another active arm for?
You dont understand what left arm does in two handed forehand. It mainly precisely guides the racket to the ball. Sometimes when you have to block very fast approaching ball you use it in a more active way.
 

oserver

Professional
You dont understand what left arm does in two handed forehand. It mainly precisely guides the racket to the ball. Sometimes when you have to block very fast approaching ball you use it in a more active way.

That means you need to train the left hand to be more passive if the incoming ball speed is average or below. Will that make the training harder; at the same time, the two hander reduce the reach considerably, making the legs doing more work than necessary. That's why I was skeptical.
 

Gregory Diamond

Professional
That means you need to train the left hand to be more passive if the incoming ball speed is average or below. Will that make the training harder; at the same time, the two hander reduce the reach considerably, making the legs doing more work than necessary. That's why I was skeptical.
4 years ago when for the first time I tried to play two handed forehand with crossed hands I was holding left hand really tight. It caused an injury of left wrist. For some time I couldnt push the ball using my left hand. I was surprised that the balls went faster and with more rotation.

I can assure you that shortened reach is not a great problem in two handed forehand because usually you play it inside the court hitting balls on the rise. That is where two handed forehend is the best. Because of your left hand you hit the ball in the right place at the right time. You would be surprised how important it is.
 

oserver

Professional
4 years ago when for the first time I tried to play two handed forehand with crossed hands I was holding left hand really tight. It caused an injury of left wrist. For some time I couldnt push the ball using my left hand. I was surprised that the balls went faster and with more rotation.

I can assure you that shortened reach is not a great problem in two handed forehand because usually you play it inside the court hitting balls on the rise. That is where two handed forehend is the best. Because of your left hand you hit the ball in the right place at the right time. You would be surprised how important it is.

'Play inside the court', you either hit in no man's land or close to it. If you watch ATP matches, how many baseline shots are hit inside the court? If you are talking about recreational play, that may be possible, but I don't hit inside the court unless opponent's return is slow or short.
 

Gregory Diamond

Professional
'Play inside the court', you either hit in no man's land or close to it. If you watch ATP matches, how many baseline shots are hit inside the court? If you are talking about recreational play, that may be possible, but I don't hit inside the court unless opponent's return is slow or short.
It is not easy to play one handed forehand inside the court. I agree with you. If millions of people used two handed forehand you would see many professional players playing inside the court.
 

oserver

Professional
It is not easy to play one handed forehand inside the court. I agree with you. If millions of people used two handed forehand you would see many professional players playing inside the court.

That's a very big 'if', isn't it? Since you need more athletic ability to use a style with both two handed forehand and backhand.
 

oserver

Professional
It is just the opposite. Almost all people who played two handed forehand were those who were not strong enough to play one handed.

Do they have stronger legs but weaker arms? Sound ill-logical to me! One need to run more to overcome the shorter reach of two handed forehand. Otherwise the overall performance will suffer.
 

Gregory Diamond

Professional
Do they have stronger legs but weaker arms? Sound ill-logical to me! One need to run more to overcome the shorter reach of two handed forehand. Otherwise the overall performance will suffer.
You should remember that players who play two handed forehand also use one handed when the ball is too far from the body. They dont have to run much more than one handed players. Could you explain why those players choose two handed when the ball is within its reach ? They could play one handed even then but they dont do it.
 

oserver

Professional
You should remember that players who play two handed forehand also use one handed when the ball is too far from the body. They dont have to run much more than one handed players. Could you explain why those players choose two handed when the ball is within its reach ? They could play one handed even then but they dont do it.

Now you have another dilemma to deal with - you have to train both one-handed/ two-handed forehands; you cannot be all good in so many ways with the same training/match playing time, can you. The results will be both forms being not optimal.
 
Last edited:

Gregory Diamond

Professional
Now you have another dilemma to deal with - you have to train both one-handed/ two-handed forehands; you cannot be all good in so many ways with the same training/match playing time, can you. The results will be both forms being not optimal.
Right hand in Two Handed Forehand works exactly the same like in one handed forehand so it is no problem for us to hit using one hand. We choose two handed forehand only because it is better than one handed.
 

Gregory Diamond

Professional
On Tuesday I found last(I hope) error in my two handed forehand. It turned out that at the beginning my left elbow had to go forward. I tried to copy forehand of Peng Shuai but it never looked the same. I tried everything. Without result. It was obvious that in the end of the stroke left hand blocked the movement of right hand and my right elbow couldnt be high at the end.
Now everybody noticed that my forehand is much more powerful.

My new forehand here.
 
Last edited:

Dragy

Legend
Guys if you missed, some lovely Polish throwing of racquet at the ball:
Well, Slovenian throwing was a tad more effective this time.
 

FiReFTW

Legend
In general, in real life, and techniques-wise (y)

Love it, i think its a straight arm forehand on most shots, and like the whole takeback and all, probably my favorite fh on wta.
In real life during this whole winter time i was indoors on hard court, she was hitting it slightly more flat there, here on clay she seems to be spinning it alot more.
 
Top