Posted by: Jack Mankin (Mrbatspeed@aol.com) on Sat May 3 15:13:33 2003

>>> These inside /short radius swings have a lot of torso turn to power them,and as Nyman has pointed out,when you hook the handpath,while bat tip velocity doesn't accelerate from this,there is additional angular acceleration of the bat ?similar to the tetherball increasing its angular velocity as the rope wraps around the pole.It would take quite an experimental setup with very high resolution to tease out and compare the various contributions of mechanics to the acceleration/shape of the swing. <<<

Hi Tom

I would assume that you are a member of Paul’s Private Discussion Board Group and thus able to speak on his behalf. Therefore, I would have to take exception to his assertion that bat tip velocity does not accelerate from the hook effect in the hand-path. To validate his position, he uses the analogy of a tetherball rope wrapping around a pole. I would agree that the ball does not increase in velocity as the angular displacement rate increases. But this analogy is not applicable in determining bat-head acceleration in the baseball swing.

In the case of the tetherball analogy, this is a closed system. The pole is neither moving nor rotating. Therefore, there is no energy being added to the system as the rope wraps around the pole. The ball’s velocity is a function of its momentum, which remains fairly constant.

But this is not the case in the baseball swing. There are two forms of energy that generate angular bat-head displacement that are constantly being supplied to the system during the hook in the hand-path. But for the time being, let us set torque (the push/pull effect of the hands) aside and concentrate on bat-head acceleration that results from the path of the hands. It is important to remember that unlike the pole in the tetherball analogy, the rotation of the body is constantly powering the angular displacement of the hands through the hook in the hand-path. This transfer of rotational energy greatly accelerates the bat-head.

A much better analogy for understanding how the hook effect accelerates the bat-head is swinging a ball on a string. You will note that you are constantly adding power to the system and that by increasing the rate of angular displacement of your hand-path (tighter circles), you will increase the velocity of the ball --- In the baseball swing, the greatest rate is reached at the hook in the hand-path.

Jack Mankin