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Re: Dr. Yeager's Whip Theory

Posted by: Brian (support@batspeed.com) on Mon Jan 10 20:01:51 2005

Hi All
> Shawn has posted on his Discussion Board ( http://s6.invisionfree.com/Hitting/index.php ) an article by Will Carroll regarding Dr. Chris Yeager's theory of the baseball swing. Dr. Yeager’s “whip” theory sounds very similar to that expressed by Professor Robert K. Adair in his book “The Physics of Baseball.” I thought it would be interesting to discuss the fundamental differences in principles of the “Whip” theory and the “Rotational Transfer” model.
> As I am sure most of you are aware, in the rotational transfer model I developed, torque (forces applied at two points from opposing directions) is a major factor in generating bat speed. However, for this discussion let us set aside the torque factor and concentrate on how the two different models transfer the body’s rotational energy into bat speed by applying a force at a single point on the handle.
> Dr. Yeager concludes that hip and shoulder rotation is generated from the transfer of momentum as the front leg stops the body’s forward movement. Although I disagree with that conclusion, I do not wish to make it a point of debate at this time. Let us just acknowledge that the batter is rotating around a stationary axis and discuss how that rotation is transferred into bat speed.
> Other than the torque factor, I think the primary conceptional difference between the “whip” and “rotational transfer” models can be shown by examining Dr.Yeager’s following statement.
> “If forward momentum is not stopped and if body segments turn at the same time, maximal energy transfer will not result. If one were to attempt to crack a whip by rotating in a circle without stopping the hand, and therefore not transferring energy, the goal of cracking the whip would not be attained. However, if we stop the whip and then allow the whip to sequentially stop down the line, then we'll get the desired result.”
> This is a very different concept than the principles governing the angular acceleration of the bat-head with the rotational transfer model. Bat-head acceleration in the rotational model is based on the same principle as swinging a ball around with a string. An angular displacement rate of the hand-path induces an angular displacement rate of the ball or bat-head.
> As Dr. Yeager points out above, with his whip theory there is no transfer of energy until the hands stop. With rotational transfer there is constant inducement of bat-head acceleration from initiation to contact as long as the hand-path is undergoing angular displacement. The greater the angular displacement rate of the hand-path, the greater the bat speed induced.
> A frame-by-frame analysis of a great hitter’s swing shows the hands do not come to a stop as required with Dr. Yeager’s whip theory. Just before contact, there is reduction in the radius of the hand-path where the bottom-hand is being pulled back around a slower moving top-hand. Some refer to it as the “hook” in the hand-path where the angular displacement rate reaches its peak. However, the hands as a unit continue a sweeping path unlike the motion used to crack a whip. – Also keep in mind that a bat can not uncoil down its length when the hands stop like a bullwhip.
> Jack Mankin


In reading Shawn's board, I now recall that Dr. Yeager stopped by the BatSpeed.com discussion board to make a few comments regarding the BatSpeed.com logo in the top left corner. It is certainly welcoming to have a new theory to discuss, but I find it interesting that Dr. Yeager was willing to discuss and debate a picture of a batter that we have said was created by our webmaster (who knows nothing about the swing), but Dr. Yeager had no interest in discussing the real merits of rotational mechanics (rotation around a stationary axis, CHP and torque). I would have been much more interested in hearing his thoughts on the future Hall of Famer's swing on the Swing Mechanics page, rather than the wisecracks at the artistic drawing.

I would also be interested in hearing Dr. Yeager's response to a few questions (I'm sure that Jack has several others) to further understand, compare and contrast his beliefs:

1) Do you believe that a batter will generate better bat speed by a) rotating around a stationary axis during the swing, or b) shifting the axis forward during the swing?

2) Do you believe that good hitters initate the swing in a circular arc or do you believe that the hands are directed back to the ball in a line ("A to B," "hands to the ball")?

3) Do you believe that Barry Bonds applies any torque at any point in his swing? If so, at what point(s) of the swing?

4) Do you believe that Barry Bonds uses your whip effect? If so, which hand during Barry Bonds' swing comes to a complete stop and exactly where does it come to a complete stop?

5) How do you explain the fact that a bat does not flex or bend like a bat in support of your whip theory. Also, would the whip effect work if a batter was attempting to swing a 10 foot 2x4 board, or would the batter then be required to apply a circular hand path with constant torque to accelerate the board?

I use Barry Bonds because he is the best hitter of our time, and, of course, each question is only a starter question in that topic area.

In any event, I wish Dr. Yeager much success with his new video.



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