Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed Jan 26 14:31:04 2005

>>> I went back and read the article. He is talking about cracking a whip and not the swing.

How you crack a whip and how you swing follow the same principles of momentum transfer, but they don't work the exact same way. The entire body is used in a swing and only the arm basically in the cracking of the whip.

If you look at the example I pointed out, you will see the accelerations and decelertion in the swing. You will se how the bat is accelerated through the actions of the kinetic sequence.

What Yeager is talking about is this kinetic sequence in the swing, how the momentum is transfered into the bat. He is talking about the block actions of the front leg.

It's interesting to note the even the arms slow down to transfer momentum into the bat.

This all comes together during the hook affect to accelerate the bat. Even if it's moving in a circular path, it's still being accelerated out or around. The knob points back towards the mass as the barrel is being accelerated out or around the mass. <<<

Hi Shawn

From your statement above, I would say we (Dr. Yeager included) are now in agreement. It appears we agree that the mechanics used to crack a whip do not represent mechanics used to swing a bat.

It also appears we agree there is a kinetic chain that rotates the shoulders from the ground up. Shoulder rotation flings, or whips, the hands into a circular path, which induces an angular displacement rate to the bat. We agree that the arms slow as rotational momentum is transferred into bat speed. Note: Tom Querry and I have referred to this transfer of momentum as “sucking of energy out of the system.”

You stated, “What Yeager is talking about is this kinetic sequence in the swing, how the momentum is transfered into the bat. He is talking about the block actions of the front leg.” – I do take exception to his theory that linear momentum is transferred to the bat by the blocking action of the front leg.

Momentum is the product of moving mass. There is no residual momentum of stationary mass. Great hitters like Bonds and Sosa may transfer a small amount of weight forward during the stride. However, all their forward movement ceases before they initiate rotation around a stationary axis. This means that before they even initiate their swings, there is no linear (forward) movement of mass. Therefore, there is no linear momentum available to be transferred to the bat. It is the body’s rotational momentum that is transferred into bat speed.

Jack Mankin