Posted by: Jack Mankin (MrBatspeed@aol.com) on Wed Dec 1 16:27:31 2004

Hi Al

Much of the November discussions of the baseball/softball swing centered on the properties of the circular hand-path (CHP). Most readers of this Site now understand that as long as the hands are accelerated in a circular path, the bat-head will also continue to accelerate in its circular path. The greater the angular displacement rate of the hands, the greater the bat speed generated. Some may refer to this as a “whipping” action.

During a discussion of “pulling the ball,” it was pointed out that unlike the tippet of a “whip,” once the bat-head passed the directional force of the hands, acceleration ceased and the bat-head was actually “decelerating.” The technical explanation for this is the physics principle that ‘mass tends to stay tangent with the direction of force.’ I doubt this technical explanation greatly advanced most coaches’ understanding of the swing. I decided an analogy might be helpful.

Basically, the point being made was that since the bat-head must pass the hands to “pull a ball’, less bat speed would be developed because the bat-head would be decelerating upon passing the hands. This argument may have some validity if it were not for the torque factor in bat-head acceleration. To explain all this, I choose to use the analogy of a skier being pulled behind a boat.

Let us first consider the analogy of a boat traveling in a straight line (straight hand-path). Obviously, if the skier held his skies neutral (pointing to the back of the boat), he would just trail straight behind the boat (tangent to the direction of force). Cutting his skies to the left accelerates him away from the centerline of the boat. The greater the angle he skies away from the centerline, the greater the force (n-factor) exerted on him to return to tangent. Once the skies return to neutral, the skier accelerates back toward centerline. As the angle decreases (n-factor), his rate of acceleration decreases and once he crosses tangent, he is decelerating (-n-factor).

Now, what does all this have to do with the baseball swing? Well, let us consider a batter with his bat cocked away (n-factor) from centerline (direction of hand thrust). The bat-head will accelerate toward centerline as the hands are extended. However, once the bat becomes tangent to the thrust of the hands, it will have decelerated and just trailed behind the hands – without a torque factor involved in the swing.

Let us take it one step further by considering the boat taking a circular path. --- As the boat makes a turn to the left, the boat’s centerline arcs away from the skier (increasing n-factor). This causes the skier (or bat-head) to also accelerate in an arc to catch up to tangent. If the boat makes a sharper turn (hook in the hand-path), the angular displacement rate (bat speed) also increases to attain tangent.

To introduce the torque factor into our analogy, let us return to the boat moving straight while the skier has set his skies to track far to the left of centerline. If the skier turns the bite of his skies sharply to the right, he would not only experience angular acceleration from the n-factor, he would also experience the added acceleration from the torque factor. Even as the n-factor is depleted approaching tangent, the skier continues arcing right past centerline due to torque. --- The same principle holds true with a batter pulling the ball (bat-head passes the direction of the hands). The depletion of CHP (zero n-factor) does not necessarily mean torque (push/pull action of the hands) is also depleted.

Final note: We must not confuse n-factor angular acceleration with the “Crack of the Whip” analogy. They are very different principles. The “Crack of the Whip” analogy is not applicable to the baseball swing.

Jack Mankin