Posted by: Jack Mankin (MrBatspeed@aol.com) on Thu Feb 11 13:53:48 2010

>>> I think that there are two forces acting on the bat.One is the centripetal force that acts on the bat as a part of the double pendulum as Adair and nyman described And then there are perpendicular forces to the barrel acting on the bat(torque or active turning of the bat)

I read an article on your board(http://www.batspeed.com/messageboard/369961.html) that states that there are strong torquing forces in the beginning that decrease as the swing goes on.

My theory is now:
for the centripetal forces to act you already need a high speed, because if you swing an object on a cord slowly there will be little centripetal force which is correlating in a function to the velocity). that means if you just pull along the axis of the bat with the chp without torque(altough having a very tight chp already has some torque since the circle is directed inward which means you pull in an angle to the bat's length) you waste several frames to accelerate the hands before the pendulum effect is effective-result: whip to late and long swing

On the other hand the torquing overcomes the innertia fast and accelerates the bathead but later when the innertia decreases it's not possible to turn as fast as the centripetal force because the bat is "unweighted". If the speed is already high active turning won't help much

So I think that in the first part of the swing forces perpendicular to the bat dominate. The task is to accelerate the head fast so that the centripetal forces tak over.
Tis phase might last to about lag position or a little longer.

Then the innertia is overcome, the bathead is released ond it whips basically by itself through centripetal force.

I don't think you can accelerate perpendicular to the length of the bat all the time. <<<

Hi Dominick

I have often stated that for a coach to correctly evaluate what constitutes efficient swing mechanics, he must have a good understanding of the forces that induces the bat's angular acceleration. It is refreshing to see you are analyzing the swing with these forces in mind.

However, I have questions regarding your following statement.-- "On the other hand the torquing overcomes the innertia fast and accelerates the bathead but later when the innertia decreases it's not possible to turn as fast as the centripetal force because the bat is "unweighted". If the speed is already high active turning won't help much"

Inertia, as it applies to the angular acceleration of the bat is a measure of the bat's resistance to changes in its rotational rate. Therefore, anytime the bat is accelerating, say from lag to contact, inertia (resistance to acceleration) remains an important factor. This requires a force (torque and pendulum effect) to be applied to overcome the inertia factor if the bat is to accelerate. -- Note: Centripetal Force is the product of angular mass velocity. It is not what accelerates the mass.


If I understand your swing mechanics theory correctly, you maintain that a strong torque force is applied at the handle to accelerate the bat to about the lag position. Then, it is the pendulum effect that accelerates the bat from lag to contact. I would contend that this might be the case with some batters' mechanics but not for others.

As an example, what about batters who are taught the linear 'A to B' extension of the hands. I think you would agree that the pendulum effect you referred to would depend on the angular displacement rate of the hand-path (a CHP). By definition, a true linear hand-path would produce no bat speed from the pendulum effect. Therefore, as the clip below demonstrates, the bat speed generated from lag to contact would be derived from torque applied at the handle and none from the pendulum effect. -- In this case, the opposite of the theory you describe.

'Whip Effect' vs CHP 'Circular-Hand-Path'

I would agree that even batters who practice extending the hands 'A to B' do not produce a true linear hand-path. There would be some degree of arc and therefore some of their bat speed derived from the pendulum effect. My best estimate would be somewhere around 25% pendulum and 75% torque. I refer to this as 'low level efficient' mechanics. I refer to it as 'low level' not only because of the hand-path, but because the torque applied (top-hand extending past a slower moving bottom-hand) is also inefficient.

We are in agreement that torque (I refer to as THT) applied at the handle does help overcome the bat's inertia during initiation which generates greater early bat speed. And, as you point out, bat speed generated from torque approaching contact is not evident in many batters. The reason these batters exhibit little torque approaching contact is because their mechanics has both the top and bottom hand applying force in relatively the same direction - forward approaching contact. This might be referred to as 'mid level efficiency.'

With 'highly efficient' mechanics (CHP, THT & BHT), this is not the case. These batters do apply torque to accelerate the bat to contact. This is because their mechanics have the hands applying force from opposing directions in the contact zone. As the video clips below show, their back-shoulder rotation is driving the back-forearm forward as their lead-forearm is being pulled rearward by lead-shoulder rotation.

Good & Bad -- BHT

Burrell & Bonds - BHT Mechanics

Your thoughts would be appreciated.

Jack Mankin