Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Hip Thrust/Back Leg
> Graylon is dead on.
> There is no stationery axis. There are two pivot points....the hands and the rear hip joint.
> As to the implication that the head must move if the rear hip moves forward is not founded in fact. There is a linear shift of the lower body forward.....the weight moves from the rear leg to front leg.....and this can be done and IS done by every high level hitter.....without any head movement.
I don't know exactly what your trying to say when you say there are two pivot points, but your comment about the axis not being stationary just sparked an explanation that will clarify what I've been trying to say this whole time.
The axis of rotation is the center of the body or the spin. But the axis itself moves, this movement of the axis is what creates the power behind the swing. The majority of the movement is forward movement toward the pitcher followed by a very slight almost indiscernible sideways movement. This very slight sideways movement is what throws the arms and the bat into an apparent circular motion. But if you were to analyze the path of the energy you'd see that the path wouldn't be circular at all, rather the path would be that of a hyperoval.
The reason that the movement of the axis, despite being so slow, still causes the bat to reach speeds in excess of 90mph is because the axis is much heavier than the bat. Even someone who only weighs 150 pounds still outweighs a 32oz bat by 75 times. If you've ever taken a physics class you'd know that the law of conservation of momentum states that final momentum is equal to initial momentum and momentum is mass multiplied by velocity. So initially we have a large mass moving slowly forward and then slightly to the side, the momentum created in this movement is then transfered to a much smaller mass (75+ times smaller) this means that the velocity of that smaller mass will be 75+ times greater than the velocity of the moving body. This is why you can attain such high batspeeds.
If you have time you can go to the following website and run the Java Application it might help better explain what I'm trying to say
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