Posted by: Mike Myers (mike.myers@bell.ca) on Thu Oct 21 15:06:00 2004

>>> Should bht's tourqe feel like tht's tourqe when applied? If I'm understanding bht correctly then I would say that tht has more tourqe. Is it because tht starts while moving slow (from a near stand still) and bht is applied to the bat while moving faster? Hope I make sense. I'm trying to teach my son how to maximize the "spank" given to the ball when bht is applied. <<<
> > >
> > > Hi Tonyd
> > >
> > > The top or bottom hand does not apply torque independently of the other. To apply torque, each hand is supplying a fairly equal force at the handle but from opposing directions. At initiation, shoulder rotation pulls the lead-hand around toward the pitcher as the top-hand is pulled back toward the catcher. This applying force from opposing directions continues throughout the swing as the body rotates. By the time the bat rotates around toward contact, the direction of the force of the hands will have reversed. Body rotation is now driving the top-hand around toward the pitcher while the rotation of the lead-shoulder to the 105 degree position is pulling the bottom-hand back toward the catcher.
> > >
> > > As I stated earlier, torque is constantly being applied throughout the swing. I termed torque applied during initiation as Top-Hand-Torque because it is the most active hand at that point. It is being pulled around a slower moving bottom-hand. And, at contact, the bottom-hand is being pulled around a slower moving top-hand – thus BHT.
> > >
> > > Tony, it may feel like the hands are exerting a greater force at initiation. However, in a smooth swing, pressure sensors indicate the force remains fairly constant. --- Most hitters have never felt the sensation of a bat accelerated from BHT. Their bottom-hand is still sweeping forward at contact as they attempt to extend the top-hand past the bottom-hand.
> > >
> > > Jack Mankin
> > >
> > >
> > >
> >
> > Jack,
> >
> > You state "it may feel like the hands are exerting a greater force at initiation. However, in a smooth swing, pressure sensors indicate the force remains fairly constant."
> >
> > Does this not contradict your Oct 4 response to Bruce (Re: Jack:Pre-launch Torque Confusion)?:
> >
> > Hi Bruce
> >
> > Your analogy with the pickup is correct. However, bat speed acquired before initiation probably has a greater impact on contact velocity than most people realize. Bonds and Sosa may only attain 3 or 4 mph bat-head velocity during pre-launch torque. But this does not mean their contact velocity is only increased by 3 or 4 mph. This is because bat-head acceleration is exponential rather than linear in nature.
> >
> > To explain this, let’s use the acceleration of a dragster for example. The acceleration of a dragster is also exponential rather than linear in nature. The dragster may only accelerate from a dead stop to 10 or 12 mph in the first second. Whereas, it may accelerate from 110 to 200 mph in the last second when coming to the finish line. Therefore, allowing the dragster a rolling start of 10 mph would not increase its speed at the finish line by only 10 mph. --- The same principle holds true with the baseball swing.
> >
> > Jack Mankin
> > ...
> >
> > How can bat-head acceleration be exponential rather than linear in nature if forces applied are constant?
> >
> > Thanks,
> > Mike.
> >
> >
>
> When the acceleration of an object is constant its velocity is not. Gravity, for example, is 32 feet per second per second. When you drop an object, it will be traveling 32 feet per second after one second, but will be traveling 64 feet per second after two seconds, 96 feet per second after three seconds, etc.
>
> If you have the equipment to analyze a swing frame by frame you will notice that the bat travels a greater distance in each frame throughout the swing indicating that acceleration is present.
>
> It makes sense that if you can apply the same force for a longer time by rotating back further then the bat should be traveling faster at the point of contact although you will have to start slightly sooner. Tom Waz

Tom,

Of course, this is the case.

I was merely identifying a contradiction in Jack's previous statements. In his Oct 4 response to Bruce he indicates "bat-head acceleration is exponential rather than linear in nature" with the analogous "acceleration of a dragster is also exponential rather than linear in nature". This suggests rate of velocity change is of power >2 (and possibly increasing):

If c=constant, and vi=0, then vf is:

If a=c, vf=ct
a=ct, vf=ct*t = ct^2
a=ct^(>1), vf=ct^(>1)*t = ct^(>2)

He today indicates bat forces applied are constant. If so, bat-head acceleration IS constant, since bat mass does not change (F=ma).

Mike.