Posted by: Dave (cdpaetkau@telus.net) on Thu May 6 00:00:30 2004

> >>> HI Jack
>
> Would you not agree though that the closer to the body (center of gravity) the hands are the faster that they will rotate. For example a figure skater will rotate faster the closer to the center of gravity that they pull in their arms. The same principals should apply to hitting just over a shorter time period.
>
> As an observation of Barry Bonds his hands are closer to his center of gravity through his swing then most players because of his batting stance where he leans over towards the plate with his upper body and his hands pass directly underneath his head. His center of gravity is pushed further towards the plate then most upright batters due to this stance. Can you comment please.
>
> Dave <<<
>
> Hi Dave
>
> Your comment raises interesting points for discussion. Let us cover your figure skater example first. – You are correct in saying that the closer to the body (center of gravity) the hands are, the faster that they will rotate. However, this does not mean that the energy in the hand-path increases as the hands are pulled in tighter. The energy remains fairly constant. The rate of body rotation increases because the resistance to body rotation decreases as the arms and hands are brought closer to the axis of rotation.
>
> Note that the skater developed the energy for rotation with the hands and arms more extended. The wider the hand-path, the more energy required to overcome the increased inertia of the longer moment-arm. Accelerating the hands and arms in a wide path developed greater momentum. As the moment-arm decreases (hands brought in tighter), momentum remained constant while resistance to rotation decreased and therefore, body rotation increased.
>
> What all of this means to the baseball swing is that slower rotation of a wider hand-path produces as much (and often more) energy as faster rotation of a tighter hand-path (Bonds vs Big Mac). One of the main reasons Bonds is successful closer to the plate is because his swing mechanics cause the bat to have a “slicing across the ball” component on inside pitches. This helps to keep pulled balls from hooking foul.
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> Jack Mankin
>

Hi Jack

That brings up more for discussion.

If you start with your hands back away from your body as you swing and then pull your hands closer to your center of gravity are you not doing that exact centrifical force energy to rotate the bat faster. Now at what point does energy output by the wider handpath become less efficient then the faster bat speed of the tigher centrifical force? This could be a full thesis project at university.

If you think of the initiation swing as a fraction of a figure skaters energy when starting with the arms and hands away from the center of gravity and as you start to swing you bring that energy into a tighter rotation are you not applying the same amount of energy on the bat but over a shorter time period and thus exerting more energy on the ball because of greater bat speed? Just think of how a figure skaters energy has been started with one complete revolution with the arms away from the body and then as they pull in tighter to the center of gravity that they now turn created enough energy to rotate 5 times for every one rotation in the same amount of time.

I look forward to your comments. Also could you please comment of my Heel to the sky question please.

Dave