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09-06-2012, 02:12 PM   #193
stoneage
Rookie

Join Date: Apr 2010
Location: Stockholm, Sweden
Posts: 243

Quote:
 Originally Posted by travlerajm Sten, Hundreds of people on this forum have tested this formula and benefited from this simple way to tune a racquet for their strokes. There is nothing erroneous about the formula, and it is indeed based on simple laws of physics.
Yes a lot of people like it, then why not be satisfied with that? Put up the specs and say "try this, I have no clue why, but it works". Instead you have decided to ice the cake with a lot of quasi physics. You are repeating time after time that it is based on simple laws of physics, but you have never been able to show it, or even tried.

Quote:
 I think perhaps you are underappreciating the importance of gravity to a tennis stroke.... 1. To take advantage of the potential energy of a high takeback, which accounts for a large fraction of the total racquet head speed through the hitting zone.
Wrong both from a mechanical and tennis perspective. Gravity acts downwards and is difficult to convert to the forward motion of the racquet when you hold it from the side. And even if you could the contribution would not be that great, 0.5 m drop would add 3 m/s to the swing speed at most. And the high take back is part of a circular swing so when the acceleration starts the position is fairly low
Federer
Djokovic

Quote:
 In order to best take advantage of the reproducible conversion of potential energy to gravity-assisted kinetic energy during the swing, a racquet must have a mass distribution that ensures that the racquethead rotates through the hitting zone at the speed that keeps the racquetface perpendicular to the target. The MgR/I formula (and the wall targeting tuning method for optimizing MgR/I) gives a very simple way to ensure that your racquet is set up optimally for this.
Another example of the quasi physics I was talking about. When I asked about a proof or background to a similar statement earlier you replied that there was no calculation or measurement but " that you could feel it in you hand". I guess that this is about as well founded.

Quote:
 Originally Posted by travlerajm Also, I choose to keep the convention of including g in the formula because g can vary significantly enough between different cities around the globe to make a noticeable difference in how my racquet plays, and I travel a lot for work, and always bring a racquet with me. For example, I will at my office in Belgium next week , where g = 981. I also travel to Buenos Aires a couple of times per year, where g = 978. The difference in racquet swing dynamics affects my swing enough that I like to look up the g value when I travel and adjust accordingly.
I am trying to decide whether this statement is outrageous or just plain funny. You need a precision that would make NASA envious: The force on the hand in a normal forehand swing parallel to the ground is about 0.00003% higher in Belgium than in Buenos Aires due to difference in gravity.

Do you take the position of Venus and Mars into account as well?

Last edited by stoneage; 09-06-2012 at 03:02 PM.