Posted by: Jack Mankin (MrBatspeed@aol.com) on Tue Feb 13 00:24:03 2001

>>>your swing test from a stationary position intrigued me. i proposed a similar (but not the same) test to paul.

under the topic " 'VOODOO' physics" which ran from 12/15/2000 thru 12/19/2000. my post - 12/17/2000 at 3:29 p.m.

never got a response from paul. tell me what you think. please? ray porco <<<

Hi Ray

I hope the below statement by you is what you wanted me to respond to.

***paul,
since i don't consider myself a "science type" and my knowledge of physics is suspect, i will revert to my extensive knowledge of "voodoo" (just kidding).
i think the greatest part of the speed that you generate from swinging one handed comes from "flail" (the first half of the swing). but our discussion at batspeed concerned extension and bottom hand torque. i would challenge the notion that you could generate more batspeed swinging one handed, as opposed to two handed, during "whip" (the second part of the swing). so, in the interest of voodoo (i mean science), let's perform a simple experiment - let's take away "flail".
get a bat and take a dry swing at an imaginery fastball, belt high, and over the heart of the plate. freeze your bat at the moment of contact. take away one hand (either one), trying not to disturb the location point of the knob of the bat. now bring the bat back as far as you can (maintaing the general location of the knob). swing. swing left handed , swing right handed , and finally, swing with both hands. take it one step further and perform the same experiment, except this time hit a ball on a tee. or have someone soft-toss to you. you have now experienced bottom hand torque.
have fun!!!
ray porco ***

First of all, I do not agree with using the term “whip” as a factor in generating bat speed. I find it is a misleading term when associated with baseball swing mechanics. I have not posted on Paul’s site and therefore not familiar with the term “Flail.” I would assume it refers to bat speed gained from the angular displacement of the hand-path.

Yes Ray, what you described is torque being applied to the bat. If the bat starts in a static state and rotates around a point between the hands, it is torque generated by the hands applying equal force from opposing directions. --- If the bottom hand is pulling the bat around a more stationary (in reference to the body) top hand, it is bottom-hand-torque. --- If the top hand is pulling the bat around a more stationary (in reference to the body) bottom hand, it is top-hand-torque.

A substantial amount (about 50%) of the bat speed is generated from the angular displacement of the hand-path (call it what you will). The balance of the bat speed (less the effect of gravity and other more minor factors) is generated from torque. From what I have read on his site, Paul, like 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.”

I took Adair’s book (and letter) and my “essay” to three college physics departments (two were Chair’s of the dept). To shorten a long story, they found that “kinetic energy transfer” not to be applicable to bat speed generation. It seems that Paul uses the same basic idea but uses “the conservation of momentum.” --- Like a goat hitting the end of a rope --- also not applicable.

Note: You can read a letter from Professor Leff to me on the site.

Jack Mankin