Miura - parametric acceleration
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Brian Manzella
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Nice Work, Mandrin.
"Miura has become the flavour of the month", made me smile as it is so true.
Thanks for your analysis and explanation. Especially the point of parametric acceleration having to be done briskly in the golf swing. That fits very well with Brian's description of the jump to yank the hula hoop out of the ground.
Thanks for your analysis and explanation. Especially the point of parametric acceleration having to be done briskly in the golf swing. That fits very well with Brian's description of the jump to yank the hula hoop out of the ground.
Nice article and Miura made big an good work to find things oust.
Mandrin, what You think is happening at figs 4a and 4b? I got that Miuras whole research somewhere but haven't red it in few years and can't find it just now, so maybe the explanation is there, but please give Your opinion, because at 4a there is no explanation how the time scale is relative to the impact.
If it goes like fig 4b seems to tell us, the centripetal force is decreasing when coming to impact and that fits totally what I've been saying and how I understand the happenings and forces there. It's not about cp-force itself, it's about what player have to resist.
Mandrin, what You think is happening at figs 4a and 4b? I got that Miuras whole research somewhere but haven't red it in few years and can't find it just now, so maybe the explanation is there, but please give Your opinion, because at 4a there is no explanation how the time scale is relative to the impact.
If it goes like fig 4b seems to tell us, the centripetal force is decreasing when coming to impact and that fits totally what I've been saying and how I understand the happenings and forces there. It's not about cp-force itself, it's about what player have to resist.
Brian Manzella
Administrator
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mandrin
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TeeAce,
Please don't take the information as treating a real golf swing. Its sole purpose is to give an intuitive knowledge of the underlying physics of parametric acceleration.
I assume that you mean to refer to Figs 3a/3b instead of Figs4a/4b.The radius is shortened in the math model. This requires a positive acceleration towards the center followed by a negative acceleration.
In this math model there is no impact, just a small weight whirling around a center and at some arbitrary times the swing radius is shortened over a short time interval
I have tried to give a more intuitive geometrical explanation why the mass increases its tangential speed when the swing radius shortens.
So why the force is changing if You keep yellowing the same word?
Brian, please open your mind a bit, because I have been struggling with these things maybe most in the world and made about all mistakes that can be done when trying to define and dig the things out. You know there is two kind of scientists, those who have made mistakes and those who will do them in the future.
I think You are quite much on right track with many things, but just doing same mistakes what I did few years ago That's why I keep asking questions, because even I can't give ready statements. It is just too complicated when we go deep enough.
There is so many obvious things we see right away.... and sometimes it takes incredibly long time to see what really happened and why.
Yes sorry about figs, I meant 3a and 3b. So the 3b is not telling about how much force there is to that direction where the arrow points? If it tells, it's just what I'm telling.
CP-force can add chs only as long as there is some lever to release. CP Force and fictional CFF are equal. And the main point: CFF is not the force we should put attention here. It's reaction to the linear force that is throwing the object away from us and it's totally depended of that linear force in golf swing. Thats why I think it has it's peak at sustain moment in swing and it's not something that causes things happen, it can be something to avoid something else happen
Brian Manzella
Administrator
I'm going with the scientists, my own research, TrackMan numbers of multiple students, lower scores of many golfers, and my own intuition.
But I will listen to you.
Since you are SO SURE that we are wrong, get right to the point, and I will take it directed to the team for a response.
You do realize that every thing you have brought here is Kinematics?
Brian, I haven't said once You are wrong. That's total misunderstanding.
I have been asking many things to find out how Your measurements are done to be able to compare those to those I've made. If there is difference on measuring, results can't be compared. That's why I keep asking things, not to say You are wrong.
During these years I have spent in Our development and research, I have mad many mistakes because of 2D illusions. Things that doctors and other technical people who don't even play golf has pointed out for me.
I have found the point where release starts about what ever is the players level. It's same point relative to some direction, but varies a lot if watched from certain angle. When I had those answers from You, I think I know quite well why You see earlier (well timed) release better than too late release that those handle draggers gets.
But this is Your forum and it might be better that I don't bring my observations here. You got my contact information and like I said when I came here, I can show something that confirms Your idea and maybe bring something more into it.
drewyallop
New
Mandrin,
Thanks for the work on parametric acceleration.
I am having trouble understanding the diagram from the Miura paper that Mike Jacobs posted here. If you have time would you provide a fuller explanation? Specifically, what are hands doing during the periods of tangential and centripetal force shown in the the diagram.
Thanks,
Drew
Thanks for the work on parametric acceleration.
I am having trouble understanding the diagram from the Miura paper that Mike Jacobs posted here. If you have time would you provide a fuller explanation? Specifically, what are hands doing during the periods of tangential and centripetal force shown in the the diagram.
Thanks,
Drew
Brian Manzella
Administrator
Tee,
Lots of folks taking huge swings at us everyday on this stuff.
So you agree with ALL of it?
mandrin
New
TeeAce,
The input information for the differential equation is given by the imposed time history of the radius as shown above. From there displacement, velocity, acceleration and force can be determined.
The information in Fig3b represents indeed the centripetal force exerted on the point mass as a consequence of the angular speed and the chosen displacement input time history for the radius.
But, I like to emphasize, this is not a golfer or a golf swing, but rather a point mass whirling bout a center.
TeeAce,
The input information for the differential equation is given by the imposed time history of the radius as shown above. From there displacement, velocity, acceleration and force can be determined.
The information in Fig3b represents indeed the centripetal force exerted on the point mass as a consequence of the angular speed and the chosen displacement input time history for the radius.
But, I like to emphasize, this is not a golfer or a golf swing, but rather a point mass whirling bout a center.
Mandrin I have a question what happens when a small mass that is connected via a rope, chain or arms and hands , to a large mass goes/travels in the opposite direction that the larger mass wants to travel in? Does the large mass travelling in a different and opposite direction exert a pulling force on the small mass and win the tug of war?
Also if they were travelling in opposite circular directions would the small mass catch up to the large mass if the large mass suddenly or slowly came to a stop? How about if the large mass wasn't moving and a small mass travelled around it and then the larger mass started to move in the opposite circular direction, what would happen?
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I don't know because I don't know what to agree.
There is so many ways to se things and here is one Do Want to Drive the Ball Further? Check Jamie Sadlowski's Swing Vision - YouTube And I don't mean to say anything about that swing, but that way of drawing lines to see angles ... it got nothing to do with reality.
Like I said I believe I have found the release starting point. I also think I know why it is at different point when watched from face on 2D, and why it gives results like You' got. But man with the answers seems now only answer with questions, so we go around here.
But Mr. Manzella, think about real directions where the hands and club head are movie at different parts of the swing. Not that what can be seen on face on video, the real directions.
I need to get my plane no and go to see what happens in Castellon masters. Sergio, Manassero, Lewis, nice pairing. I try to also see if Daly still got some lag there. See You
Why do you think Brian and the scientists don't understand the difference between 2D and 3D? Because of that one model that was discussed earlier? He already answered that is just one model used in their research. As Brian said there is a lot of information that he has not talked about yet.
Brian Manzella
Administrator
ALL OF NESBIT"S WORK WE ARE USING IS 3D.
3D.
3D.
mandrin
New
Drew,
Could give me an idea where to find this particular post. There is none by Michael Jacobs in this thread.
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