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Re: Re: Re: Re: Re: Torque


Posted by: Jack Mankin (MrBatspeed@aol.com) on Sat Jan 5 02:09:23 2002


>>> jack....major dan also said "Energy is transferred up the kinetic chain into shoulder rotation. If the arms are properly 'connected' to the shoulder turn, the angular velocity of the shoulders is imparted to the hands/arms/bat. However, as the shoulders decelerate, the energy is transferred to the hands/arms/bat which is thrown out of the shoulder rotation arc, momentarily picking up speed, not slowing down. "

Hi grc

When you state; "However, as the shoulders decelerate, the energy is transferred to the hands/arms/bat which is thrown out of the shoulder rotation arc, momentarily picking up speed, not slowing down", are you saying that the hands/arms are "picking up speed" as the bat-head approaches maximum velocity? Sorry grc, but I am having trouble understanding your point.

>>> are you now willing to accept the concept of the "kinetic chain".....if i remember right, in the past you was skeptical of (hostile to?)this concept.......respectfully, grc.....<<<

"Rotation around a stationary" and the "kinetic chain" are the same concepts. They differ in name only. As far back as the late 1980's, I was arguing for those concepts when 99.9 % of the coaches (Ted Williams being the only exception I can think) were arguing that a "linear weight shift" as being the source of energy for the swing. Professor Adair (author: "The Physics of Baseball") was a leading proponent for weight shift (linear kinetic energy transfer) argument and completely discounted rotation around a stationary axis. Below is a post I made earlier on the subject.

PS: I have had a problem with those coaches that believe the "kinetic chain" could supply energy to the bat without shoulder rotation or efficient transfer mechanics.

##
Professor Adair (author: "The Physics of Baseball") does not believe the balance of the bat speed is generated from torque. In fact, Adair does not believe torque is a factor at all in developing bat speed. He stated in his book, and to me, that any force applied by the hands to the handle of the bat would have a negligible effect on the bat head.

Professor Adair believes (as outlined in his book) that it is the release of kinetic energy that accounts for the bat's acceleration from 40 to 70+ mph. In his model of the swing, the body's center of mass MUST move forward 12 to 18 inches at 6 to 8 mph DURING the swing. Then, as the forward progression of the body and hands slows to a near stop, the body's kinetic energy is transferred and accelerates the bat-head.

I wrote to Professor Adair that frame-by-frame video analysis showed that although the batter may take a timing step, the forward body progression came to a stop before rotation and forward movement of the hands started. That the batter then rotated around a stationary axis and there was no further forward movement of body mass during the swing. Professor Adair wrote back, and I quote; "I found your essay on batting quite unpersuasive even as it was non-quantitative. And any batter who would use your "stationary axis" model, taken literally, could not hit a ball past second base."

Jack Mankin


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