bren2001 wrote: » At what point did I say any of that was negligible? I don't know if you're intentionally misunderstanding what I said about shaft bend or not but when you're doing a mathematical analysis at the point of impact, what has happened before is irrelevant. The bend is taken into account by the shape of the club at the point of impact. That's how shaft bend is taken into account in a simple model. My statement was relating to the deflection of the shaft in the moment before impact and the moment after. An infintely small amount of time. I don't believe the deflection that occurs due to the strike of the ball in this time-frame is a significant factor. The model and mathematical analysis I've stated in this thread is solely to demonstrate that the weight of a player has an impact on distance. It is not a full model to actually calculate the distance a ball would travel. You would need a much more sophisticated model for that. Most likely a DAE. I don't particularly want to waste my time talking to a brick wall. My only point is that the weight of a golfer impacts the distance a ball will travel. I am not saying what other factors are important. It seems to me that you've accepted that weight does matter in a golf swing but you don't want to admit you are wrong and are now trying to twist your argument or move the goalposts. Very simply, do you now accept that the weight of a golfer does impact the distance a ball will travel? That's the only point I've been trying to convey.
Henry Ford III wrote: » Magnificent strawman. Simply outstanding. Why does every other pro use different length irons?
GreeBo wrote: » No I don't. I started saying the ball didn't care about anything other than impact, you started saying the golfers weight is relevant, I'm saying is not and you haven't been able to demonstrate anything to the contrary. I asked would iron Byron hit it further if you have it heavier and you ignored it. I asked various similar questions and you ignored them. The ball is hit by the club and distance depends on the force, which is the mass times acceleration of the club. The same club at the same speed hits the ball the same distance. Why is Rory longer than koepka with the same swing speed and 20kg lighter?
Golf is my Game wrote: » With yere maths theres also the mistake in trying to make it to a static situation because it isnt. While the time the clubs in contact with the ball is very small and so intuitively we tend to think of it as an instant in fact the time the ball is in contact is very important and is a critical element in the pros getting their distance and spin on the ball. The ball is very elastic, and the club head slightly elastic. The acceleration/deceleration of the clubhead and what your swing timing is doing to it for the period of contact is crucial to the compression of the ball. the transfer of clubhead speed to ball speed, and to the spin put on it as a result. Swing timing that maximises the time the club is in contact with the ball is what allows top players put such back spin on the ball that they can control it on the green, even with short clubs where high clubhead speed is not required they can do it. Its a dynamic impact. Low level golf simply never get such spin on the ball to have the ball spin back on the green because they arent able to sustain the club head speed as it contacts the ball (they fool them selves sometimes that they do when a ball jumps back out of its pitch mark but that werent the spin).
First Up wrote: » The ONLY factor affecting distance is the speed at which the club hits the ball. Fat golfers, thin golfers, light golfers, heavy golfers, tall golfers and short golfers will all hit the ball exactly the same distance if they hit it with the same clubhead speed. The real question is how does a golfer's weight influence the clubhead speed they can generate. I don't think it does - but muscular strength might.
bren2001 wrote: Can you explain why a golfers weight doesn't effect distance but the linked article above shows that a baseball players weight effects distance? What is the fundamental difference? Why would a golfers weight not feature in the conservation of momentum or energy laws?
First Up wrote: » Is there evidence that baseball players (or golfers) of different weights but the same swing speeds achieve different distance? In any case, baseball is not a good comparison; a baseball is moving before being hit which is an important variable. A golf ball is static.
bren2001 wrote: Yes there is a difference but why would the mass of the golfer be taken out in the kinetic energy calculation but not for the baseball player?
First Up wrote: » Weight is only a factor if it contributes to force, generating speed. Weight on it's own is meaningless, unless it translates into strength, generating greater force (speed).
bren2001 wrote: The article I linked explains that weight is a factor in its own right for generating force through kinetic energy. Why would that be the case for baseball but not for golf?
First Up wrote: » Baseball and golf are different (I have played both) but I still await evidence that a golfer weighing 120 kilos generating the same clubhead speed will hit a golf ball further than a golfer weighing 90 kilos.
bren2001 wrote: Otherwise, can you please explain from a mathematical perspective why the weight of the golfer would not be taken into account in either the law of conservation of momentum or energy. If neither are applicable (they both are), can you please outline how you would calculate the initial ball speed from a kinematics perspective?
First Up wrote: » I'd prefer to do it from a golfing perspective. There is plenty of data showing the direct relationship between clubhead speed and distance. None of it is qualified by the weight of the person generating it.
Golf is my Game wrote: » Yeh, if you go to your pro he never tells you you need to put on a few stone or has a scales in his teaching bay to see if youve got enough momentum through the ball. Not on TV. They dont comment on how players who lose weight like Bubba last year, or I though Rahm is looking slimmer this weekend, is going to lose distance and its going to cost him so he should go back on the pasta and cream cakes. Looking at the long hitters out there theres no correlation evident between the long lads and the short ones and their weight or even size. Rory is a small enough and light lad for example. Its all about speed. How many yards would you say or would your equations back up, that a stone is worth to a tipical golfer ? Im an engineer too, but washing machines and dishwashers mainly rather than sports but, so still have a good feel for mechanics.
bren2001 wrote: » The relationship between clubhead speed and distance is well established. I'm not saying that's untrue. I'm sayi g the weight of a person makes a difference, that's all. That difference might be very very small. Ok, from a golfing perspective, the kinetic energy before impact is 0.5mv^2, the m refers to the mass of the golf club and golfer. Why is that wrong?
Golf is my Game wrote: » That you are counting all of the body of the golfer contributing to the mass in the 1/2mv2 equation. v is a vector with direction as well as magnitude. You are using all that v as if it were in the direction of the target. The 1/2mv2 component that resolves for the movement of the body of the golfer is neglectably zero since the v of the movement of the body as a mass is almost zero. The body itself simply isnt moving fast. And the remainder of the compnonent that is, is almost a zero sum, since mass of the body that is actually moving back (the left half for a right handed golfer) from the ball negates that which is moving toward the ball (the right side). Leaving no body momentum component that has any measureable contribution to energy transferred to the ball.
bren2001 wrote: Ok, from a golfing perspective, the kinetic energy before impact is 0.5mv^2, the m refers to the mass of the golf club and golfer. Why is that wrong?
First Up wrote: » The relationship between clubhead speed and distance is well documented and none of it mentions the weight of the golfer swinging the club. Why not?
bren2001 wrote: » I may be misreading what you are saying but any time I've hit a ball. My body is moving towards the target, not away from it. My centre of gravity is moving forward so my bodies momentum is forward. My body isn't static. My weight is shifting from my back foot to my front foot. It doesn't sum to zero, when you resolve the "force" it will be positive along the target line. My body is rotating. So v is not 0, it's a positive number.
bren2001 wrote: » Can you explain why this would be different for a baseball player as per the Penn State research linked above? Why would their kinetic energy not sum to zero?
bren2001 wrote: » If you're accepting that v is positive, then you accept that mass does have an effect. You just think it is negligible. We disagree there, I don't think it's negligible but I do think it's small. I don't see the point in arguing over semantics in that case. I disagree with how you've done the above. You've effectively treated the club and body as two separate masses. You are joined at the hands and are one large mass. I don't think you can break it down like that nor have I ever seen it broken down like that.
bren2001 wrote: » See the article here:https://qz.com/801738/...aseball-players-fat/ Research by Penn State. Yes there is a difference but why would the mass of the golfer be taken out in the kinetic energy calculation but not for the baseball player?
bren2001 wrote: I believe if you took a golfer who weighed 0kg and a golfer who weighed 80kg hit the ball with the same swing, same ball, at the same speed etc. The 80kg golfer will hit it noticeably further. If the difference is 60kg to 80kg, the difference in length gets smaller and smaller to the point it is negligible.
bren2001 wrote: Can you please explain why it doesn't apply, they are both humans swinging a club/bat. Mathematically, they are very similar.
Golf is my Game wrote: » You should be moving back as you hit the ball if you want to emulate the pros. Rory's back move is credited with a small sling shot effect that gives him the big distance. Even without it, his head and shoulders are moving distinctly back as he hits the ball. Most golfers are. The forward weight transfer you describe happens in the trasnition and much of the down swing, but then either becomes stationary as the shoulders spin as the wrists straighen to the ball, or the upper torso moves back wards as above. But while this contradicts what you are saying, the main reason body motion doesnt matter is that at the point of impact is it spinning, not moving forward. I know nothing of the baseball swing. Lets keep it to golf. Does your interest in the baseball one say you cannot find supporting evidence on golf. Which is interesting. I am saying v is only purely positive for the club head. For the body much of it is negative : the upper torso and head moving backwards and the left side also rotating backwards. Much of the rest of the body has already moved from back to forward and is no longer moving forward, or forward at such a low speed that it has no relevant effect on the energy to transfer to the ball.
GreeBo wrote: » Your article doesn't say so prove what you think it does. Firstly "in theory, if a bigger guy is just as fast or strong as another guy, he should be able to hit the ball further,” Karakolis says." In theory, not fact. Secondly they stress the point what matters to the ball is angular velocity, it doesn't matter how you generate this. They go on to state that a bigger guy needs more power to move at the same speed as a smaller guy. Finally, the whole point all along has specifically been about all other factors being equal. If you swing at 100mph then as long as you can resist the impact, or "remain stiff" in your article.l it doesn't matter what you weigh, it matters how much you can resist and get COR as close to 1, i.e. strength not mass or weight. Golf differs from baseball at impact because golfers hands and forearms are passive compared to baseball where they are actively resisting.
bren2001 wrote: Based on the above, I believe you are either refusing to listen to another point of view or refuse to admit you are incorrect in your statement.
First Up wrote: » Have you any data that shows that any variable other than clubhead speed is a factor in how far a golf ball travels?
